Blood, 15 March 2001, Vol. 97, No. 6, pp. 1817-1822
IMMUNOBIOLOGY
Interleukin-6 is a growth factor for nonmalignant human
plasmablasts
Gaëtan Jego,
Régis Bataille, and
Catherine Pellat-Deceunynck
From the Institut National de la Santé et de la
Recherche Médicale (INSERM) U463 and Laboratoire
d'Hématologie, Institut de Biologie, Nantes, France.
Interleukin-6 (IL-6), although often regarded as a B-cell
differentiation factor, was recently described as the essential survival factor for human plasmablasts in vivo in reactive
plasmacytosis. The present study reinvestigated the roles of IL-6 and
IL-2 in the generation of plasma cells from human memory B cells in
vitro. The cells involved in this differentiation process were
identified as preplasmablasts
(CD20±CD38±CD138
), plasmablasts
(CD20CD38++CD138), and early
plasma cells
(CD20CD38+++CD138+++). IL-2 or
IL-10 induced a strong generation of plasmablasts and early plasma
cells (PCs). Compared to IL-2 or IL-10, IL-6 alone was inefficient at
PC generation. However, when combined with IL-2 or IL-10, IL-6 enhanced
generation of early PCs. Moreover, anti-IL-6 monoclonal antibody
markedly reduced IL-2-induced generation of early plasma cells, but
not of plasmablasts. These roles of IL-2 and IL-6 were consistent with
the difference in the expression of their respective receptors (R).
CD25 (IL-2R
) was increased 72 ± 10-fold on activated B cells, but
decreased and then disappeared on plasmablasts. Conversely, CD126
(IL-6R) was barely expressed on activated B cells, but increased
18 ± 2-fold on preplasmablasts. Finally, IL-6 enhanced the
proliferation (2-fold increase) of IL-2-generated plasmablasts. In
conclusion, the data indicate that IL-6 is a growth factor for
nonmalignant human plasmablasts.
