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Blood, 15 November 2001, Vol. 98, No. 10, pp. 3035-3041
IMMUNOBIOLOGY
Splenectomy of rats selectively reduces lymphocyte
function-associated antigen 1 and intercellular adhesion molecule 1 expression on B-cell subsets in blood and lymph nodes
Novica M. Mili evi,
Birgit Luettig,
Christian Trautwein,
Torsten Wüstefeld,
Michael Mähler,
Peter Jecker,
Kurt Wonigeit, and
Jürgen Westermann
From the Institute of Histology and Embryology, Faculty
of Medicine, University of Belgrade, Yugoslavia; Institute of Anatomy,
Medical University of Lübeck, Lübeck, Germany; Department
of Gastroenterology and Hepatology, Medical School of Hannover,
Germany; Central Animal Facility, Medical School of Hannover,
Germany; Department of Otolaryngology, Mainz Medical School,
Mainz, Germany; Visceral and Transplantation Surgery, Medical School of
Hannover, Germany.
Splenectomy increases the number of B cells in the blood of humans
and animals. It is unknown whether this is due to changes in migration,
proliferation, or both. The numbers of naïve
(IgD+IgM+), memory
(IgD IgMhigh), newly formed
(IgMhighCD90high), early recirculating
follicular (IgMlowCD90high), recirculating
follicular (IgMlowCD90), and marginal zone
(IgMhighCD90) phenotype B cells were
determined in control and splenectomized rats by flow cytometry. All
subsets increased significantly in the blood after splenectomy. Because
surface molecules are involved in the regulation of migration and
proliferation, their expression (lymphocyte function-associated antigen
1 [LFA-1], intercellular adhesion molecule 1 (ICAM-1),
L-selectin,  4-integrins, CD44, major histocompatability
complex class II, interleukin 2 receptor- chain) was determined on
B- and T-cell subsets of both groups. B cells, but not T cells, showed
a significantly reduced LFA-1 and ICAM-1 expression in blood and lymph
nodes, whereas the expression of the other surface molecules analyzed
remained unchanged. The down-regulation of these molecules did not
influence the adherence of B cells to high endothelial venules in
vitro. In vivo, however, ICAM-1low-expressing B cells
migrated significantly faster through lymph nodes
(ICAM-1low 41 ± 5 hours versus ICAM-1high
58 ± 3 hours), whereas proliferation of B cells in bone marrow, lymph node, and blood remained unchanged. Thus, the presence of one
organ is necessary for appropriate expression of LFA-1 and ICAM-1 on B
cells in other, distant organs. The more rapid transit of
ICAM-1low B cells through lymph nodes may be responsible
for the increased B-cell number in the blood after splenectomy.
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