Ia-mediated signal transduction leads to proliferation of primed B lymphocytes.
One of the most controversial questions in immunology is the molecular basis by which Th lymphocytes deliver activating signals to quiescent B lymphocytes during T cell-dependent immune responses. Recent studies suggest that T cell-dependent activation of quiescent B lymphocytes may involve signaling mediated by direct T helper cell-B cell contact. Since B cell membrane-associated MHC-encoded class II molecules (Ia) must be recognized by Th lymphocytes for generation of T cell-dependent humoral immune responses, they are obvious candidates for receptors of this signal. Here we report that stimulation of quiescent murine B cells with IL-4 and antibodies against the B cell antigen receptor for 12-16 h primes cells to proliferate in response to immobilized mIa binding ligands. In the presence of additional lymphokines, these B cells differentiate to secrete Ig of IgM and IgG classes. These results suggest that Ia molecules are receptors for direct, T helper cell-B cell contact mediated signaling that results in B cell proliferation.
Cambier
J C
JC
Department of Pediatrics, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206.
Lehmann
K R
KR
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D002453:Cell Cycle; D000949:Histocompatibility Antigens Class II / Q000276:immunology / Q000502:physiology*; D007075:Immunoglobulin M / Q000276:immunology; D015847:Interleukin-4; D007378:Interleukins / Q000494:pharmacology; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D015398:Signal Transduction
D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II; D007075:Immunoglobulin M; D007378:Interleukins; D015847:Interleukin-4