Resting B lymphocytes can be triggered directly through the CDw40 (Bp50) antigen. A comparison with IL-4-mediated signaling.
Resting tonsillar B lymphocytes were shown to enlarge and become more buoyant when exposed to either IL-4 or a mAb (G28-5) to the 50-kDa CDw40 Ag. A striking feature of activation through CDw40 was the promotion of strong homotypic adhesions which did not occur in populations cultured with IL-4. Whereas the CDw40 antibody down-regulated its target Ag, an increased expression of CDw40 accompanied IL-4 stimulation. Similarly, only IL-4, and not the CDw40 antibody, was able to induce the appearance of CD23 on the resting B cell surface. Functionally, the major consequence of ligating CDw40 on resting B cells was that they remained alert to subsequent mitogenic signaling--cells incubated with IL-4 developed the same sluggish response as noted in control cultures. Together, IL-4 and the CDw40 antibody provoked a small, but significant, level of DNA synthesis in tonsillar B cells which was enhanced dramatically by the inclusion of low m.w. B cell growth factor. This latter agent had no discernible direct effect on resting B lymphocytes. The different pathways which have been observed for triggering resting B cells are discussed.
Gordon
J
J
Department of Immunology, University of Birmingham, UK.
Millsum
M J
MJ
Guy
G R
GR
Ledbetter
J A
JA
D000911:Antibodies, Monoclonal / Q000502:physiology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000502:physiology*; D002449:Cell Aggregation; D002478:Cells, Cultured; D006801:Humans; D015847:Interleukin-4; D007378:Interleukins / Q000494:pharmacology*; D007399:Interphase; D008213:Lymphocyte Activation; D008934:Mitogens / Q000494:pharmacology; D010641:Phenotype
D000911:Antibodies, Monoclonal; D000944:Antigens, Differentiation, B-Lymphocyte; D007378:Interleukins; D008934:Mitogens; D015847:Interleukin-4