Relationships between the degree of cross-linking of surface immunoglobulin and the associated inositol 1,4,5-trisphosphate and Ca2+ signals in human B cells.
Cross-linking of surface immunoglobulin (Ig) receptors on human B cells leads to the activation of a tyrosine kinase. The activated tyrosine kinase subsequently phosphorylates a number of substrates, including phospholipase C-gamma. This enzyme breaks down phosphoinositol bisphosphate to form two intracellular messengers, diacylglycerol and inositol 1,4,5-trisphosphate, leading to the activation of protein kinase C and the release of intracellular Ca2+ respectively. We have used h.p.l.c. and flow cytometry to measure accurately the inositol phosphate turnover and Ca2+ release in anti-Ig-stimulated human B cells. In particular, we have examined the effect of dose of the cross-linking antibody on the two responses. The identity of putative messenger inositol phosphates has been verified by structural analysis, and the amounts of both inositol phosphates and Ca2+ present have been quantified. In the Ramos Burkitt lymphoma, which is very sensitive to stimulus through its Ig receptors, both inositol phosphate production and Ca2+ release were found to be related to the dose of anti-Ig antibody applied. This suggests that phospholipase C-mediated signal transduction in human B cells converts the degree of cross-linking of the immunoglobulin receptor quantitatively into intracellular signals.
McConnell
F M
FM
Regional Primate Research Center, University of Washington, Seattle 98195.
Shears
S B
SB
Lane
P J
PJ
Scheibel
M S
MS
Clark
E A
EA
D001402:B-Lymphocytes / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003432:Cross-Linking Reagents; D004789:Enzyme Activation; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism; D014066:Palatine Tonsil / Q000166:cytology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
D002413:Cations, Divalent; D003432:Cross-Linking Reagents; D007295:Inositol Phosphates; D011947:Receptors, Antigen, B-Cell; D015544:Inositol 1,4,5-Trisphosphate; D011505:Protein-Tyrosine Kinases; D002118:Calcium