Inhibitory action of sulfatide, a putative ligand for L-selectin, on B cell proliferation and Ig production.
The interaction of L-selectin and its ligand is widely accepted to mediate leukocyte rolling and adhesion on the endothelial surface. Although L-selectin is ubiqultously expressed on lymphoid cells, its role in execution of lymphocyte functions is unknown. By flow cytometric analysis using mAb specific for sulfatide, a putative ligand for L-selectin, we found that sulfatide was selectively expressed on B cells, but not on T cells. To elucidate the involvement of L-selectin and its ligand in B cell activation, the present study was undertaken to investigate effects of sulfatide on T cell-dependent and -independent Ig production by B cells. In pokeweed mitogen-stimulated cultures, addition of sulfatide resulted in almost complete inhibition of Ig production by B cells in the presence of memory CD4+ T cells, whether L-selectin-positive or -negative. A similar inhibition of Ig production by sulfatide was found when B cells were stimulated with Staphylococcus aureus Cowan I and IL-2. Unlike sulfatide, a desulfated form of sulfatide, galactosylaceramide, did not show any effects on Ig production by B cells. Maximal inhibition of Ig production was observed when sulfatide was added at the early period of culture. Sulfatide suppressed effectively proliferation of B cells, but not of T cells. Sulfatide competed the binding of anti-L-selectin mAb to B cells, suggesting it could interfere B cell activation by blocking L-selectin function. The results suggest a novel role of the L-selectin/its ligand system in the initiation of B cell activation.
Konno
A
A
Department of Pediatrics, School of Medicine, Faculty of Medicine, Kanazawa University, Ishikawa, Japan.
Nunogami
K
K
Wada
T
T
Yachie
A
A
Suzuki
Y
Y
Takahashi
N
N
Suzuki
T
T
Miyamoto
D
D
Kiso
M
M
Hasegawa
A
A
Miyawaki
T
T
D000328:Adult; D000917:Antibody Formation / Q000187:drug effects*; D001402:B-Lymphocytes / Q000187:drug effects* / Q000378:metabolism*; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects*; D005699:Galactosylceramides / Q000494:pharmacology; D006801:Humans; D019041:L-Selectin / Q000187:drug effects* / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000187:drug effects; D008024:Ligands; D008213:Lymphocyte Activation / Q000187:drug effects*; D011485:Protein Binding / Q000502:physiology; D013433:Sulfoglycosphingolipids / Q000378:metabolism / Q000494:pharmacology*
D005699:Galactosylceramides; D008024:Ligands; D013433:Sulfoglycosphingolipids; D019041:L-Selectin