Antigen-independent regulation of cytoplasmic calcium in B cells with a 12-kDa B-cell growth factor and anti-CD19.
Increases in cytoplasmic free calcium ([Ca2+]i) can be induced in resting B cells either by a low molecular weight (12-kDa) B-cell growth factor (LMW-BCGF) or by crosslinking the B-cell antigen CD19 with monoclonal antibody (mAb). LMW-BCGF causes a slow [Ca2+]i increase in peripheral blood and tonsillar B cells but has no effect on [Ca2+]i in resting T cells. B-cell [Ca2+]i responses mediated by anti-surface immunoglobulin (sIg) or anti-CD19 are potentiated by LMW-BCGF, but anti-sIg and anti-CD19 do not show additive [Ca2+]i responses. LMW-BCGF- and anti-CD19-induced [Ca2+]i signals are similar to the sIgM or sIgD-mediated signals in that they are inhibited by prior treatment with phorbol 12-myristate 13-acetate. However, LMW-BCGF- and CD19-mediated signals do not depend on the expression of sIg, since they were also observed on sIg-B-cell precursor acute lymphoblastic leukemia (ALL) cells. Both anti-CD19 and LMW-BCGF stimulated in vitro colony formation by ALL cells and showed additive effects when used together. [Ca2+]i responses to LMW-BCGF or CD19 cross-linking were also evident on certain pre-B-cell and lymphoma B-cell lines.
D000911:Antibodies, Monoclonal; D018941:Antigens, CD19; D000954:Antigens, Surface / Q000276:immunology*; D001402:B-Lymphocytes / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002454:Cell Differentiation; D003593:Cytoplasm / Q000378:metabolism*; D006801:Humans; D015847:Interleukin-4; D007378:Interleukins / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D018941:Antigens, CD19; D000954:Antigens, Surface; D007378:Interleukins; D015847:Interleukin-4; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium