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 Previous Article | Table of Contents | Next Article 
Blood, Vol. 91 No. 4 (February 15), 1998:
pp. 1355-1361
Interleukin-7 (IL-7) Enhances Class Switching to IgE and IgG4 in
the Presence of T Cells Via IL-9 and sCD23
By
Pascale Jeannin,
Yves Delneste,
Sybille Lecoanet-Henchoz,
Denise Gretener, and
Jean-Yves Bonnefoy
From the Geneva Biomedical Research Institute, Immunology Department,
Glaxo Wellcome Research and Development SA, Geneva, Switzerland.
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ABSTRACT |
Interleukin-7 (IL-7) is a B-cell growth factor produced by both bone
marrow stroma cells and follicular dendritic cells (FDCs) located in
primary lymphoid follicles and germinal centers. In this study, we have
evaluated the role of IL-7 on human Ig class switching. IL-7 was added
to peripheral blood mononuclear cells (PBMCs) or tonsillar B cells in
the absence or presence of IL-4 and/or anti-CD40 monoclonal
antibody (MoAb). Alone, IL-7 did not affect Ig production by PBMCs or
by anti-CD40 MoAb-stimulated B cells. Rather, IL-7 potentiated
IL-4-induced IgE and IgG4 production by PBMCs. In parallel, IgG3
production was also enhanced but to a lesser extent, whereas the
production of the other isotypes was unaltered. The activity of IL-2,
IL-9, or IL-15, which share usage of the common  chain for
signaling, was also assessed. IL-9, like IL-7, potentiated mainly IgE
and IgG4 production by IL-4-stimulated PBMCs. IL-15, in contrast, was
ineffective, whereas IL-2 enhanced the production of all isotypes. More
precisely, IL-7 potentiation of IgE and IgG4 production required the
presence of T cells and was accompanied by an increase of the
expression of two soluble molecules favoring preferentially IgE and
IgG4 synthesis: CD23 (sCD23) and IL-9. Moreover, neutralizing anti-CD23 and anti-IL-9 antibodies partly inhibited the increase of IgE synthesis induced by IL-7. Thus, IL-7 produced locally in the germinal
centers by FDCs may interact with T cells and potentiate human IgE and
IgG4 switching by favoring IL-9 and sCD23 production.
| |
INTRODUCTION |
INTERLEUKIN-7 (IL-7), produced by stroma
cells and follicular dendritic cells (FDCs), exerts its effects through
a receptor (IL7R) composed of an  and a chain.1-4
The chain (c) is a common component of the receptors for IL-2,
IL-4, IL-9, and IL-15.5-7 IL7R controls T-cell
lymphopoiesis and potentiates the proliferation and the production of
lymphokines by mature T cells.8-10 IL-7 also has a critical
role in B-cell lymphopoiesis because it favors the commitment of murine
progenitor cells towards pro-B cells and promotes the growth and
differentiation of pro-B and early pre-B cells.2,11
Furthermore, IL-7 enhances Ig recombinase gene activity in human
progenitor B cells and consequently may affect VDJ
recombination.12 However, the effect of IL-7 on isotype switching remains undefined.
After activation, surface IgM+IgD+ human B
cells switch to express different isotypes of antibody (Ab; IgG1-4,
IgA1-2, or IgE). This process, which occurs mainly in the T-cell-rich
apical zone of germinal centers is highly controlled by soluble
cytokines and by B-T-cell interactions involving the CD40
molecule.13-15 The regulation of IgE switching, which has
been extensively studied, requires two primary signals: the first,
furnished by IL-4 or IL-13, induces the expression of the sterile
transcript; the second, provided by the B-T-cell interaction and
mimicked in vitro by CD40 triggering (using either CD40 ligand
[CD40L] or an anti-CD40 monoclonal antibody [MoAb]), induces the
expression of the mature transcript.16,17 IgE
production is tightly controlled by costimulatory signals mediated by
cell-cell contact and soluble mediators: The triggering of CD21 with
CD23 and the cytokines IL-2, IL-6, and IL-9 upregulate IgE
production,18-21 whereas interferon- (IFN-), IFN-,
transforming growth factor- (TGF-), IL-10, IL-12, and PGE2 induce
downregulation.22-25
Based on the observation that IL-7 is produced in the germinal centers
where the switch process takes place,4,14 we have evaluated
whether or not it may affect isotype switching. We report that IL-7 has
no direct effect on human B cells but potentiates, in the presence of T
cells, IL-4-induced IgE and IgG4 switching.
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MATERIALS AND METHODS |
Cell preparations.
Peripheral blood mononuclear cells (PBMCs) were isolated by
centrifugation on Ficoll/Paque (Pharmacia, Uppsala, Sweden). In some
experiments, monocytes were removed by a two-step adherence assay on
Sephadex G10 columns (Pharmacia), as described.26 In others, T-cell depletion was performed by sheep red blood cells rosetting. Residual T cells were labeled with anti-CD3 MoAb
(Immunotech, Marseille, France) and removed with magnetic beads coated
with anti-mouse Ig Ab (Dynal, Oslo, Norway). The percentage of residual monocytes or T cells determined by flow cytometry on a FACStar Plus
cytofluorometer (Becton Dickinson, Erembodegem, Belgium) after labeling
with fluorescein isothiocyanate (FITC)-labeled anti-CD14 or anti-CD2
MoAbs (both from Becton Dickinson), respectively, were <1%. Human B
cells were purified from tonsils as described.27 Cells were
cultured in enriched Iscove's medium.27
Ig assays.
Cells were added at 2 × 105/200 µL/well in 96-well
plates (Nunc, Roskilde, Denmark) and stimulated, in replicates of five, with 0.5 to 50 ng/mL of human recombinant IL-7 (R&D Systems,
Minneapolis, MN), 10 ng/mL of either IL-2 (Geneva Biomedical Research
Institute [GBRI], Geneva, Switzerland), IL-9 (R&D Systems), or IL-15
(Genzyme, Cambridge, MA) in the absence or presence of 200 U/mL of IL-4 (GBRI), 0.1 µg/mL anti-CD40 MoAb (Serotec, Oxford, UK), or
combinations of IL-4 plus anti-CD40 MoAb. In some experiments, PBMCs
were stimulated with IL-4 in the presence of 10 ng/mL of IL-1, IL-3,
IL-5 (all from GBRI), IL-8, IL-9, IL-11, IL-12, IFN- (all from R&D
Systems), IL-6, tumor necrosis factor- (both from AMS Biotechnology,
Lugano, Switzerland), or TGF1 (Sigma, St Louis, MO). In other
experiments, PBMCs were stimulated with IL-4 in the presence or absence
of 10 ng/mL of IL-7 with or without 20 µg/mL of neutralizing mouse IgG1 anti-CD23 MoAb (clone Mab 25, Serotec),28 neutralizing goat IgG anti-IL-9 Ab (R&D Systems), control mouse IgG1 MoAb, or
control goat IgG Ab (both from Sigma). Supernatants were collected at
day 12 to quantify Ig.
Ig quantification.
IgA1-2, IgE, IgG1-4, and IgM were quantified by enzyme-linked
immunosorbent assay (ELISA) as described.27,29 Results are expressed in ng/mL or as a percentage of increase of Ig production defined as followed: (A O/O) × 100, where A and O were the
concentrations of Ig produced in the presence or absence of IL-7,
respectively.
Proliferation assays.
Cells (2 × 105/200 µL/well) were stimulated in
quintuplicate as described and pulsed at day 2 with 0.25 µCi/well
3H-thymidine (Amersham International, Amersham, UK) for 6 hours. Radioactive incorporation was measured by standard liquid
scintillation counting. Results are given in counts per minute (cpm) or
as a stimulation index (SI) calculated as follows: A/O, where A and O
were the cpm values obtained when cells were or were not cultured in
the presence of the cytokine tested, respectively.
Immunostaining.
PBMCs were stimulated with 200 U/mL of IL-4 in the absence or presence
of 10 ng/mL of IL-7. The expression of different cell surface antigens
was evaluated at different time points by flow cytometry on B and T
cells derived from PBMCs. PBMCs were incubated with FITC-labeled
anti-CD21, -CD23, -CD40, control MoAbs (all from Becton Dickinson),
CD23-, or glycophorin-A-fluorescent liposomes (used as a negative
control) or with biotinylated anti-CD40L MoAb (all from GBRI). The
binding of biotin-anti-CD40L was shown by FITC-labeled streptavidin
(Sigma). B and T cells were identified using phycoerythrin (PE)-labeled
anti-CD19 or anti-CD3 MoAbs, respectively (both from Becton Dickinson).
Results are given as the expression of surface markers (frequency and
mean fluorescence intensity [MFI] of positive cells)
among B and T cells.
Quantification of soluble mediators.
IL-4 and IFN- were quantified by ELISA using specific capture and
detection MoAbs from Pharmingen (San Diego, CA) and Genzyme, respectively. IL-6 and soluble CD23 (sCD23) were measured with ELISA
kits from R&D Systems and Innogenetics (Zwijndrecht, Belgium), respectively.
Analysis of IL-9 mRNA expression by polymerase chain reaction (PCR).
PBMCs were either unstimulated or stimulated with 200 U/mL of IL-4
and/or 10 ng/mL of IL-7 for 24 hours. IL-9 mRNA expression was
analyzed by PCR as previously described.30 Briefly,
pelleted cells were resuspended in 1 mL of Trizol reagent (Life
technologies, Basel, Switzerland). After addition of 0.2 mL chloroform,
total RNA was precipitated by isopropylic alcohol. The single-strand cDNA was synthesized using 1 µg of total RNA by reverse transcription using an oligo-dT primer (Pharmacia). cDNA corresponding to 20 ng of
total RNA was used for the amplification reactions. Each PCR reaction
tube contained 10 mmol/L Tris-HCl (pH 8.3), 50 mmol/L KCl, 1 mmol/L
MgCl2, 0.01% gelatin, 2 U AmpliTaq DNA polymerase (Perkin-Elmer Cetus, Norwalk, CT), 0.2 mmol/L of each deoxynucleotide (Pharmacia) and 1 µmol/L of each primer. Sequences of the
oligonucleotides for the IL-9 transcript are as follows:
5 -ATGCTTCTGGCCATGGTCCT-3 and
5-TATCTTGCCTCTCATCCCTC-3. Control consisted of amplifying -actin transcripts using the following primers:
5-CGATTTCCCGCTCGGCCGTGGTGGTGAAGC-3 and
5-GGCGACGAGGCCCAGAGCAAGAGAGGCATC-3. The amplification
consisted of one cycle for 4 minutes at 94°C followed by 35 cycles
for 30 seconds at 94°C, 60°C for 1 minute, and 72°C for 1 minute. The final extension cycle was for 5 minutes at 72°C. PCR
products were size-separated on a 1% agarose gel and visualized by
ethidium bromide staining.
Analysis of IgE mRNA transcription by Northern blotting.
PBMCs were either unstimulated or stimulated for 10 days with 200 U/mL
of IL-4 and/or 10 ng/mL of IL-7. Total RNA extraction and
hybridizations were performed with cRNA probes complementary to C
and -actin mRNA.17 IgE protein was quantified in the
supernatants by ELISA.
Statistical analysis.
Statistical significance was determined using the Student's
t-test.
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RESULTS |
IL-7 potentiates IL-4-induced IgE and IgG4 production by PBMCs.
The production of IgE, which results from the stimulation of PBMCs with
IL-4, is upregulated by different cytokines such as IL-2, IL-6, and
IL-919-25 (Fig 1A). We report
that IL-7 also potentiates IL-4-induced IgE and IgG4 synthesis; this
effect is significant with 1 (P < .01) and maximal with 10 ng/mL of IL-7 (increase in IgE and IgG4 of 850% ± 120% and 990% ± 125%, respectively, mean percent ± standard
deviation [SD], n = 6; Fig 1B). In parallel, IgG3 production is
weakly increased (increase of 264% ± 90%), whereas IgA1-2,
IgG1-2, and IgM production are unaffected (Fig 1C). As
expected,8,31 IL-7 also increases the proliferation of
PBMCs either unstimulated (SI, 5 ± 1.2, mean ± SD, n = 3) or stimulated with IL-4 (SI, 4 ± 0.9;
Table 1).
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| Fig 1.
Effect of IL-7 on Ig production by PBMCs from healthy
subject. (A) IL-7 increases IgE production by IL-4-stimulated PBMCs. IL-4-stimulated PBMCs were incubated with 10 ng/mL of the different cytokines and IgE was quantified by ELISA. (B) IL-7 increases IgE and
IgG4 production in a dose-dependent manner. PBMCs were stimulated with
IL-4 with or without 0.5 to 50 ng/mL of IL-7. IgE ( ) and IgG4 (1:10)
( ) were quantified by ELISA. (C) Effect of IL-7 on the production of
other isotypes by 200 U/mL of IL-4-stimulated PBMCs. PBMCs were
stimulated with 200 U/mL of IL-4 without () or with () 10 ng/mL
of IL-7 before quantification of IgA1, IgA2, IgG1-3, and IgM by ELISA.
(D) IL-7 potentiates IL-4-induced IgE and IgG4 production in the
absence of anti-CD40 MoAb. IgE and IgG4 were quantified in the
supernatants of PBMCs either unstimulated or stimulated with IL-4,
anti-CD40 MoAb, or combination of IL-4 plus anti-CD40 MoAb in the
absence () or presence () of 10 ng/mL IL-7. (A-D) Ig isotypes
were quantified in the day-12 supernatants. Results are expressed in ng
or µg/mL (as mean ± SD of quintuplicate values) and are
representative of one of four (A and C) or six (B and D) separate
experiments. * indicates P < .01.
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Table 1.
Comparison Between the Effect of IL-7 and Either IL-2,
IL-9, or IL-15 on Proliferation and IgE Production by PBMCs or Purified B
cells
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PBMCs either unstimulated or stimulated with anti-CD40 MoAb produce low
levels of IgG4 (<25 ng/mL, n = 6) and no IgE. In both cases, addition
of IL-7 does not induce IgE nor affect the production of IgG4 (Fig 1D)
or other Ig isotypes (data not shown). Moreover, the stimulation of
PBMCs with IL-4 plus anti-CD40 MoAb results in a large production of
IgE and IgG4, which is unaffected by IL-7 (Fig 1D). Thus, IL-7
synergizes with IL-4 to induce IgE and IgG4 production by PBMCs.
IL-7 increases IL-4-induced transcript expression by PBMCs.
In view of the preceding results, we have evaluated whether or not IL-7
affects the expression of the transcripts. PBMCs either unstimulated or stimulated with IL-7 do not express the
transcripts. A stimulation with IL-4 is required to induce their
expression resulting in IgE production (Fig
2).16,17 Addition of IL-7 enhances the expression of both
the sterile and mature transcripts induced by IL-4 (Fig 2). Thus,
IL-7 potentiates IL-4-induced IgE synthesis by enhancing the
transcript expression.
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| Fig 2.
IL-7 enhances transcripts expression. PBMCs were
either unstimulated or stimulated with IL-7 and/or IL-4 for 10 days. RNA was isolated and used for Northern blot analysis using probes complementary to C (upper panel). As control, probes specific for
actin were used (lower panel). In parallel, IgE was quantified in the
day-10 supernatants.
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Comparison between the effect of IL-7 and other cytokines in which
receptors use the c.
Like IL-7, the cytokines IL-2, IL-4, IL-9, and IL-15 have specific
receptors that use the c and modulate B-cell
functions.5-7,16,19-21,32 Moreover, IL-2, IL-4, and IL-9
control IgE synthesis.16,19-21 As such, we have compared
the effect of these cytokines on IgE synthesis with those of IL-7.
IL-2, IL-7, IL-9, and IL-15 are unable to replace IL-4 or anti-CD40
MoAb in inducing IgE production by purified B cells nor do they
modulate IgE production induced by IL-4 plus anti-CD40 MoAb (Table 1).
Nevertheless, IL-2, IL-15,32 and to a lesser extent IL-9
have a direct effect on B cells because they increase the proliferation
of B cells either unstimulated or stimulated with an anti-CD40 MoAb,
whereas IL-7 is ineffective (SI <2; Table 1).
Except for IL-4, none of these cytokines induce IgE (Table 1) nor IgG4
production (data not shown) by PBMCs. However, IL-2, IL-7, and IL-9
potentiate IL-4-induced IgE and IgG4 synthesis by PBMCs whereas IL-15
is ineffective. IL-2 and IL-7 are more efficient than IL-9 (increase of
IgE production of 900% ± 100%, 850% ± 120%, and 336% ± 66%, respectively; mean% ± SD, n = 3; Fig 3). As observed with IL-7, IL-9 does
not significantly affect IgA1, IgA2, IgG1, and IgG2 production and only
increases IgG3 production to a small extent (increase of 220% ± 79%; Fig 3). In contrast, IL-2 potentiates the production of all the
isotypes, mainly IgA1 and IgA2 (increase of 1,460% ± 150% and
2,300% ± 350%, respectively; Fig 3). As previously
reported,33 in contrast to the T-cell growth factors IL-2,
IL-7, and IL-15,8,31,34 IL-9 does not enhance the
proliferation of PBMCs either unstimulated or stimulated with IL-4
(SI <2; Table 1). Thus, IL-7 appears more potent than IL-9
and more selective than IL-2 in potentiating IL-4-induced IgE and IgG4
synthesis by PBMCs.
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| Fig 3.
Comparison of the effect that IL-2, IL-7, IL-9, and IL-15
have on Ig production by IL-4-stimulated PBMCs. PBMCs were stimulated with 200 U/mL of IL-4 without or with 10 ng/mL IL-2, IL-7, IL-9, or
IL-15. IgA1, IgA2, IgE, and IgG1-4 were quantified using supernatants harvested after 12 days of culture. Results are expressed in percent of
Ig increase as described in the Material and Methods and are representative of one of three experiments.
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IL-7 requires the presence of T cells to potentiate IgE and IgG4
production.
To test whether IL-7 enhances IgE synthesis by acting directly on B
cells, we have compared its ability to modulate IgE production by
purified B cells and by PBMCs depleted either in monocytes or in T
cells.
B cells require a stimulation via both the IL-4 receptor and CD40 to
produce IgE.16 IL-7 does not induce IgE production by
tonsillar B cells, either unstimulated or stimulated, with IL-4 or
anti-CD40 MoAb nor does it modulate IgE production induced by IL-4 plus
anti-CD40 MoAb (Fig 4A). Such lack of
activity of IL-7 was also observed with purified peripheral blood B
cells (data not shown). In parallel, IL-7 does not affect other
isotypes' production by anti-CD40 MoAb-stimulated B cells (data not
shown) nor the proliferation of B cells, either unstimulated or
stimulated, with anti-CD40 MoAb (SI <2; Table 1).
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| Fig 4.
Evaluation of the effect of IL-7 on IgE production by
different cell populations. (A) IL-7 does not affect IgE production by
purified B cells. Tonsillar B cells were either unstimulated or
stimulated with IL-7 and/or IL-4 in the absence () or
presence ( ) of anti-CD40 MoAb. IgE were quantified in the day-12
supernatants. (B) The effect of IL-7 on IgE production requires the
presence of T cells. PBMCs depleted or not () of monocytes (×10)
() or of T cells () were either unstimulated or stimulated with
IL-7 and/or IL-4. IgE was quantified in the supernatant of 12 days. (A and B) Results are expressed in ng/mL (as mean ± SD of
quintuplicate values) and are representative of one of three separate
experiments.
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Monocyte-depleted PBMCs stimulated with IL-4 produce very low levels of
IgE (0.8 ng/mL ± 0.3, mean ± SD, n = 3),19,24 and the addition of IL-7 potentiates this production (increase of 501% ± 120%, n = 3; Fig 4B).
As expected, IL-4 or anti-CD40 MoAb does not induce IgE production by
PBMCs in which T cells are depleted (Fig 4B) or cultured in an insert
(data not shown).15,16,19 In both conditions, addition of
IL-7 is unable to induce it. Thus, IL-7 does not modulate IgE
production by purified B cells but potentiates IL-4-induced IgE
synthesis via T-cell-mediated events.
Effect of IL-7 on IgE-regulating pathways.
To understand the mechanism responsible for the effect of IL-7 on IgE
and IgG4 synthesis by PBMCs, we have evaluated whether or not IL-7
modulates the expression of cell-associated (CD21, CD23, CD40, and
CD40L) or soluble molecules (IL-4, IL-6, IL-9, IFN-, and sCD23) that
control IgE and IgG4 production.16-21,23
Stimulation of PBMCs with IL-4 results in an increase of membrane CD23
expression and in the binding of CD23-liposomes to B
cells16,18; in contrast, CD21 and CD40 expression is
unaffected and CD40L expression remains undetectable. Addition of IL-7
to IL-4-stimulated PBMCs for 1, 3, or 5 days does not modulate the
expression of CD21, CD23, and CD40 nor affect the binding of CD23
liposomes and does not induce CD40L expression on B cells
(Table 2A). In parallel, the expression of
both CD23 and CD40L is undetectable on T cells derived from PBMCs
either unstimulated or stimulated with IL-4 and/or IL-7,
whatever the time point analyzed (data not shown).
IL-7 increases the spontaneous production of IL-6, IFN-, and sCD23
by PBMCs (increase of 51% ± 9%, 150% ± 21%, and 63% ± 12%, n = 4) but does not induce IL-4 production (Table 2B). When added
to IL-4-stimulated PBMCs, IL-7 does not affect IFN- production but
upregulates IL-6 and sCD23 production (increase of 102% ± 18% and
190% ± 27%, respectively; Table 2B). Interestingly, the expression of mRNA encoding for the T-cell-derived cytokine, IL-9, is
undetectable in PBMCs stimulated for 24 hours with IL-4 or IL-7 but is
induced by stimulation with both IL-4 plus IL-7
(Fig 5). Thus, IL-7 increases sCD23 and to
a lesser extent IL-6 production and upregulates IL-9 mRNA transcription
by IL-4-stimulated PBMCs.
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| Fig 5.
IL-7 synergizes with IL-4 to upregulate IL-9 mRNA
expression. PBMCs were either unstimulated or stimulated with IL-4
and/or IL-7. After 24 hours, IL-9 mRNA expression was evaluated
by PCR.
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IL-7 potentiation of IgE synthesis is mediated at least partly
through an enhancement of both sCD23 and IL-9 expression.
As IL-9 and sCD23 costimulate preferentially IgE and IgG4 synthesis by
IL-4-stimulated PBMCs,18,20,21 we have evaluated whether
IL-7 enhances IgE synthesis by increasing their production. As
expected, the neutralizing anti-CD23 MoAb, Mab 25, decreases IgE
production by IL-4-stimulated PBMCs (decrease of 84% ± 8%, n = 4)18,28 (Fig 6). A neutralizing
anti-IL-9 Ab also decreases IgE synthesis by IL-4-stimulated PBMCs
(decrease of 65% ± 11%; Fig 6). When PBMCs are stimulated with
IL-4 plus IL-7, addition of the anti-CD23 or anti-IL-9 Ab decreases
IgE production to a similar extent as observed in the absence of IL-7
(decrease of 86% ± 10% and 73% ± 9%, respectively; Fig 6).
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| Fig 6.
IL-7 potentiation of IL-4-induced IgE synthesis is at
least partly through sCD23 and IL-9. PBMCs were stimulated with IL-4 in
the absence () or presence of 10 ng/mL IL-7 () with or without neutralizing anti-CD23 MoAb (Mab 25), neutralizing goat anti-IL-9 IgG,
control mouse IgG1, or control goat IgG. IgE was quantified in the
day-12 supernatants. Results are expressed in percent of decrease as
mean ± SD of four experiments.
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Thus, IL-7 may potentiate IgE synthesis, at least in part, by enhancing
both sCD23 and IL-9 production.
| |
DISCUSSION |
We have shown in this study that IL-7 synergizes with IL-4 to induce
human IgE and IgG4 production in a T-cell-dependent manner. This
effect is mediated at least in part through an increase of both sCD23
and IL-9 production.
The lymphokines that use the c for signal transduction, IL-2, IL-4,
IL-7, IL-9, and IL-15, affect B-cell functions.19-21,32 Thus, we have compared their effect on IgE synthesis. Firstly, in
contrast to IL-4, we confirm that IL-2, IL-9, and IL-15 are not switch
factors for IgE and extend this observation to IL-7. Secondly, although
IL-2 and IL-15 have comparable activities on purified B cells (both
increase proliferation and IgA, IgG, and IgM production induced by
anti-CD40 MoAb),32 we found that they differentially
modulate IgE and IgG4 production by IL-4-stimulated PBMCs. IL-2
induces a potent increase of the production of IgE, IgG4,19
and other isotypes by IL-4-stimulated PBMCs. In contrast, IL-15 does
not increase IgE and IgG4 production. These data suggest that the
effects of IL-2 and IL-15 on T cells or monocytes probably differ.
Thirdly, we have shown that IL-7 and IL-9 have a similar effect on IgE
and IgG4 production by PBMCs because they both potentiate IL-4-induced
IgE and IgG4 and, in a lower extent, IgG3 production. Although it has
been proposed that IL-9 may potentiate IL-4-induced IgE synthesis by
acting directly on B cells,20,21 we reported no direct
effect of IL-9 on IgE production by IL-4 plus anti-CD40 MoAb-stimulated
B cells. Finally, although IL-2, IL-4, IL-7, and IL-9 positively
control IgE synthesis, each lymphokine presents an individual pattern
of effects based on differences in intensity and selectivity of the
response and on the nature and the degree of maturation of the target
cells. These differences could be related to an effect on distinct cell
subpopulations or to binding to receptors associated with a specific
intracellular signaling pathway. Nevertheless, the main point is that,
in contrast to IL-2, both IL-7 and IL-9 costimulate preferentially IgE
and IgG4 synthesis.
IL-7 is crucial for murine B lymphopoiesis2 but poorly
affects human precursor B-cell proliferation and
development.12,35 Furthermore, IL7R expression disappears
during the B-cell maturation process.2,36 Both these
observations may explain the absence of effect of IL-7 on B-cell
proliferation reported in this study. Interestingly, results suggest
that IL-7 acts through T cells to potentiate IgE and IgG4 production.
Thus, IL-7 may affect the production/expression by T cells of factors
that control IgE synthesis, such as IL-4, IL-6, IL-9, IL-13, IFN-,
sCD23, or the cell surface molecules CD23, CD21, or
CD40L.16,18,19-21,23,30 Based on different data, it seems
unlikely that IL-7 increases IgE production by enhancing the expression
of the IgE switch factors, IL-4 and CD40L. Supraoptimal concentrations
of exogenous IL-4 are present in these experiments. In accordance with
data showing that IL-7 potentiates IL-4 production by T cells but does
not induce it,9,10 we found that PBMCs stimulated with IL-7
do not produce IL-4. Moreover, membrane CD40L expression is
undetectable on T cells derived from IL-437 or IL-4 plus
IL-7-stimulated PBMCs. Finally, IL-7 does not replace IL-4 or CD40
triggering and, as such, is not a switch factor for IgE.
We have then evaluated whether IL-7 modulated the production of
lymphokines such as IL-619 or IFN-,23 which
potentiate or inhibit IgE synthesis, respectively. IL-7 induces a weak
increase of IL-6 production by IL-4-stimulated PBMCs. This effect
cannot explain the selective increase of IgE and IgG4 production
induced by IL-7, because IL-6 also favors the other isotypes'
production.38 As IFN- decreases the synergistic effect
of IL-4 and IL-7 on IgE production (data not shown), we could have
expected IL-7 to decrease IFN- production by IL-4-stimulated PBMCs.
However, IL-7 does not affect IFN- production by IL-4-stimulated
PBMCs but, in contrast, increases IFN- production by unstimulated
PBMCs.10
Finally, as signaling through CD2118 and IL-9R
preferentially costimulate IgE/IgG4 production, we have tested whether
or not IL-7 affects IL-9 production and/or CD23-CD21
interaction. Although IL-7 increases membrane CD23 expression on
phytohemagglutinin-activated T cells,39 it does not induce
CD23 expression on T cells derived from IL-4-stimulated PBMCs or
increase CD21 and CD23 expression on B cells or CD23 binding to CD21.
IL-7 has been shown to enhance sCD23 production by human T
cells.40 In accordance with this observation, we report
that IL-7 increases sCD23 production by IL-4-stimulated PBMCs and that
this increase may explain its costimulatory role on IgE
production.18 Then, based on the observation that IL-7
synergizes with IL-4 in upregulating the expression of the T-cell-derived cytokine IL-9,30 we have analyzed the
effects of a neutralizing anti-IL-9 Ab on IgE synthesis. This Ab
decreased IgE synthesis by PBMCs stimulated by IL-4 in the presence or
absence of IL-7, thereby reinforcing the costimulatory role of IL-9 in the regulation of IgE synthesis.20,21 In conclusion,
although we cannot exclude the involvement of other mechanisms, these
data suggest that IL-7 potentiates IL-4-induced IgE synthesis by
enhancing sCD23 and IL-9 production.
In conclusion, these data provide evidence for a role of IL-7 in the
regulation of human isotype switching. IL-7 synergizes with IL-4 to
induce IgE and IgG4 synthesis. This effect requires the presence of T
cells and is, at least in part, caused by an enhancement of sCD23 and
IL-9 production. Isotype switching, which has been recently shown to
occur in T-cell-rich zones of the secondary follicles from human
tonsils, is directed by multiple signals provided by T
cells.13-15 Thus, IL-7 produced locally by the
FDCs4 may act on T cells to potentiate IL-4-induced IgE
switching. Allergic disorders are associated with a production of IgE
and with a predominant Th2 T-cell response (characterized by the
production of IL-4, IL-5, and IL-941,42). The recent
evidence of IL-7 together with IL-4 and IL-5 in the skin from atopic
patients after allergenic challenge reinforces a potential role of IL-7
in IgE-associated diseases.43
| |
FOOTNOTES |
Submitted June 16, 1997;
accepted October 14, 1997.
Address reprint requests to Pascale Jeannin, PhD, Centre
d'Immunologie Pierre Fabre, 5, Av Napoleon III, BP 97, F-74164
Saint-Julien en Genevois, Switzerland.
The publication costs of this article were defrayed in part by page
charge payment. This article must therefore be hereby marked
"advertisement" in accordance with 18 U.S.C. section 1734 solely
to indicate this fact.
| |
ACKNOWLEDGMENT |
We thank Dr M.H. Kosco-Vilbois for critical reading of the manuscript.
| |
REFERENCES |
1.
Goodwin RG,
Friend D,
Ziegler SF,
Jerzy R,
Falk BA,
Gimpel S,
Cosman D,
Dower SK,
March CJ,
Namen AE,
Park LS:
Cloning of the human and murine interleukin-7 receptors: Demonstration of a soluble form and homology to a new receptor superfamily.
Cell
60:941,
1990[Medline]
[Order article via Infotrieve]
2. Kunisada T, Ogawa M, Hayashi SI, Era T, Nishikawa SI:
Interleukin-7 and B lymphopoiesis, in Kishimoto T (ed): Interleukins: Molecular Biology and Immunology. Chem Immunol (vol 51). Basel, Switzerland, Karger, 1992, p 205
3. Noguchi M, Nakamura Y, Russel SM, Ziegler SF, Tsang M, Cao X,
Leonard WJ: Interleukin-2 receptor gamma chain: A functional component
of the interleukin-7 receptor. Science 262:1877, 1993
4.
Kroncke R,
Loppnow H,
Flad HD,
Gerdes J:
Human follicular dendritic cells and vascular cells produce IL-7: A potential role for interleukin-7 in the germinal center reaction.
Eur J Immunol
26:2541,
1996[Medline]
[Order article via Infotrieve]
5.
Kondo M,
Takeshita T,
Ishii N,
Nakamura M,
Watanabe S,
Arai KI,
Sugamura K:
Sharing of the interleukin-2 (IL-2) receptor gamma chain between receptors for IL-2 and IL-4.
Science
262:1874,
1993[Abstract/Free Full Text]
6.
Giri JG,
Ahdieh M,
Eisenman J,
Shanebeck K,
Grabstein K,
Kumaki S,
Namen A,
Park LS,
Cosman D,
Anderson D:
Utilization of the beta and gamma chains of the IL-2 receptor by the novel cytokine IL-15.
EMBO J
13:2822,
1994[Medline]
[Order article via Infotrieve]
7.
Kimura Y,
Takeshita T,
Kondo M,
Ishii N,
Nakamura M,
Van Snick J,
Sugamura K:
Sharing of the IL-2 receptor gamma chain with the functional IL-9 receptor complex.
Int Immunol
7:115,
1995[Abstract/Free Full Text]
8.
Armitage RJ,
Namen AE,
Sassenfeld HM,
Grabstein KH:
Regulation of human T cell proliferation by IL-7.
J Immunol
144:938,
1990[Abstract]
9. Dokter WHA, Sierdsema SJ, Esselink MT, Halie MR, Wellenga E:
Interleukin-4 mRNA and protein in activated human T cells are enhanced
by IL-7. Exp Hematol 22:74, 1994
10.
Borger P,
Kauffman HF,
Postma DS,
Vellenga E:
IL-7 differentially modulates the expression of IFN and IL-4 in activated human T lymphocytes by transcriptional and post transcriptional mechanisms.
J Immunol
156:1333,
1996[Abstract]
11. Namen AE, Lupton S, Hyerrild K, Wignall J, Mochizuki DY,
Schmierer A, Mosley B, March CJ, Urdal D, Gillis S, Cosman D, Goodwin
RG: Stimulation of B-cell progenitors on human and murine B lineage
cells. Nature 33:571, 1988
12.
Billips LG,
Nunez CA,
Bertrand FE,
Stankovic AK,
Gartland GL,
Burrows PD,
Cooper MD:
Immunoglobulin recombinase gene activity is modulated reciprocally by interleukin 7 and CD19 in B cell progenitors.
J Exp Med
182:973,
1995[Abstract/Free Full Text]
13.
Liu YL,
Arpin C,
De Bouteiller O,
Guret C,
Banchereau J,
Martinez-Valdez H,
Lebecque S:
Sequential triggering of apoptosis, somatic mutation and isotype switch during germinal center development.
Semin Immunol
8:169,
1996[Medline]
[Order article via Infotrieve]
14.
Liu YL,
Malisan F,
De Bouteiller O,
Guret C,
Lebecque S,
Banchereau J,
Mills FC,
Max EE,
Martinez-Valdez H:
Within germinal centers, isotype switching of immunoglobulin gene occurs after the onset of somatic mutation.
Immunity
4:241,
1996[Medline]
[Order article via Infotrieve]
15.
Stavnezer J:
Antibody class switching.
Adv Immunol
61:79,
1996[Medline]
[Order article via Infotrieve]
16. (suppl)
De Vries JE,
Yssel H:
Modulation of the human IgE response.
Eur Resp J
22:58S,
1996
17.
Gauchat JF,
Lebman DA,
Coffman RL,
Gascan H,
de Vries JE:
Structure and expression of germline epsilon transcripts in human B cells induced by interleukin 4 to switch to IgE production.
J Exp Med
172:463,
1990[Abstract/Free Full Text]
18.
Aubry JP,
Pochon S,
Graber P,
Jansen KU,
Bonnefoy JY:
CD21 is a ligand for CD23 and regulates IgE production.
Nature
358:505,
1992[Medline]
[Order article via Infotrieve]
19.
Maggi E,
Del Prete GF,
Parronchi P,
Tiri A,
Macchia D,
Simonelli C,
Ricci M,
Romagnani S:
Role for T cells, IL-2 and IL-6 in the IL-4-dependent in vitro human IgE synthesis.
Immunology
68:300,
1989[Medline]
[Order article via Infotrieve]
20. Dugas B, Renault JC, Pene J, Bonnefoy JY, Petit-frere C, Braquet
P, Bousquet J, Van Snick J, Mencia-Huerta JM: IL-9 potentiates the
IL-4-induced immunoglobulin (IgG, IgM and IgE) production by normal
human B lymphocytes. Eur J Immunol 23:1687, 1993
21.
Petit-Frere C,
Dugas B,
Braquet P,
Mencia-Huerta JM:
Interleukin-9 potentiates the interleukin-4-induced IgE and IgG1 release from murine B lymphocytes.
Immunology
79:146,
1993[Medline]
[Order article via Infotrieve]
22. Gauchat JF, Aversa G, Gascon H, de Vries JE: Modulation of IL-4
induced germline epsilon RNA synthesis in human B cells by tumor
necrosis factor-alpha, anti-CD40 monoclonal antibodies or transforming
growth factor-beta correlates with levels of IgE production. Int
Immunol 4:397, 1992
23.
Pene J,
Rousset F,
Briere F,
Chretien I,
Bonnefoy JY,
Spits H,
Yokota T,
Arai N,
Arai KI,
Banchereau J:
IgE production by normal human lymphocytes is induced by interleukin 4 and suppressed by interferons and and prostaglandin E2.
Proc Natl Acad Sci USA
85:6880,
1988[Abstract/Free Full Text]
24.
Punnonen J,
de Waal Malefyt R,
van Vlasselaer P,
Gauchat JF,
de Vries JE:
IL-10 and viral IL-10 prevent IL-4-induced IgE synthesis by inhibiting the accessory cell function of monocytes.
J Immunol
151:1280,
1993[Abstract]
25.
Kiniwa M,
Gately M,
Gubler U,
Chizzonite R,
Fargeas C,
Delespesse G:
Recombinant interleukin-12 suppresses the synthesis of immunoglobulin E by interleukin-4 stimulated human lymphocytes.
J Clin Invest
90:262,
1992
26.
Bonnefoix T,
Sotto JJ,
Pegourie B,
Piccini MP:
Stimulation and inhibition of human granulopoiesis in vitro by normal and malignant T4- or T8-lymphocyte subpopulations.
Exp Hematol
15:645,
1987[Medline]
[Order article via Infotrieve]
27.
Henchoz-Lecoanet S,
Jeannin P,
Aubry JP,
Graber P,
Bradshaw CG,
Pochon S,
Bonnefoy JY:
The Epstein Barr virus-binding site on CD21 is involved in CD23 binding and IL-4-induced IgE and IgG4 production by human B cells.
Immunology
88:35,
1996[Medline]
[Order article via Infotrieve]
28.
Bonnefoy JY,
Schields J,
Mermod JJ:
Inhibition of human interleukin 4-induced IgE synthesis by a subset of anti-CD23/Fc epsilon RII monoclonal antibodies.
Eur J Immunol
20:139,
1990[Medline]
[Order article via Infotrieve]
29.
Jeannin P,
Delneste Y,
Lecoanet-Henchoz S,
Gauchat JF,
Ellis J,
Bonnefoy JY:
CD86 (B7-2) on human B cells: A functional role in proliferation and selective differentiation into IgE and IgG4-producing cells.
J Biol Chem
272:15613,
1997[Abstract/Free Full Text]
30.
Houssiau FA,
Schandené L,
Stevens M,
Cambiaso C,
Goldman M,
Van Snick J,
Renaud JC:
A cascade of cytokines is responsible for IL-9 expression in human T cells. Involvement of IL-2, IL-4, and IL-10.
J Immunol
154:2624,
1995[Abstract]
31.
Londei M,
Verhoef A,
Hawrylowicz C,
Groves J,
Berdinis PD,
Feldman M:
Interleukin-7 is a growth factor for mature human T cells.
Eur J Immunol
20:245,
1994
32.
Armitage RJ,
Macduff BM,
Eisenman J,
Paxton R,
Grabstein KH:
IL-15 has stimulatory activity for the induction of B cell proliferation and differentiation.
J Immunol
154:483,
1995[Abstract]
33.
Houssiau FA,
Renauld JC,
Stevens M,
Lehmann F,
Lethe B,
Coulie PG,
Van Snick J:
Human T cell lines and clones respond to IL-9.
J Immunol
150:2634,
1993[Abstract]
34.
Grabstein KH,
Eisenman J,
Shanebeck K,
Rauch C,
Srinivasan S,
Fung V,
Beers C,
Richardson J,
Schoenborn MA,
Ahdieh M,
Johnson L,
Alderson MR,
Watson JD,
Anderson DM,
Giri JG:
Cloning of a T cell growth factor that interacts with the beta chain of the interleukin-2 receptor.
Science
264:965,
1994[Abstract/Free Full Text]
35. Prieyl JA, LeBien TW: Interleukin 7 independent development of
human B cells. Proc Natl Acad Sci USA 93:10348,
1996
36.
Appasamy PM:
Interleukin-7: Biological and potential clinical applications.
Cancer Invest
11:487,
1993[Medline]
[Order article via Infotrieve]
37. Gauchat JF, Aubry JP, Mazzei G, Life P, Jomotte T, Elson G,
Bonnefoy JY: Human CD40-ligand: Molecular cloning, cellular distribution and regulation of expression by factors controlling IgE
production. FEBS Lett. 315:259, 1993
38.
Bertolini JN,
Benson EM:
The role of human interleukin-6 in B-cell isotype regulation and differentiation.
Cell Immunol
125:197,
1990[Medline]
[Order article via Infotrieve]
39.
Carini C,
Fratazzi C:
CD23 expression in activated human T cells is enhanced by interleukin-7.
Int Arch Allergy Immunol
110:23,
1996[Medline]
[Order article via Infotrieve]
40. Fratazzi C, Carini C: Interleukin-7 modulates intracytoplasmic
CD23 production and induces adhesion molecule expression and
adhesiveness in activated CD4+CD23+ T cell
subsets. Clin Immunol Immunopathol 81:261 1996
41.
Romagnani S:
Th1 and Th2 in human diseases.
Clin Immunol Immunopathol
80:225,
1996[Medline]
[Order article via Infotrieve]
42.
Renauld JC,
Kermouni A,
Vink A,
Louahed J,
Van Snick J:
Interleukin-9 and its receptor: Involvement in mast cell differentiation and T cell oncogenesis.
J Leuk Biol
57:353,
1995[Abstract]
43. (suppl)
Yamada N,
Wakugawa M,
Kuwata S,
Nakagawa H,
Tamaki K:
Changes in eosinophil and leukocyte infiltration and expression of IL-6 and IL-7 messenger RNA in mite allergen patch test reactions in atopic dermatitis.
J Allergy Clin Immunol
98:S201,
1996[Medline]
[Order article via Infotrieve]
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Abstract
Introduction
Abstract