Comparison of tyrosine kinase activation by mitogenic and nonmitogenic anti-IgD antibodies.
Low concentrations of anti-Ig dextran conjugates that stimulate very high levels of B cell proliferation and Ig secretion stimulate no detectable increases in tyrosine phosphorylation. To study this point further, we compared tyrosine phosphorylation patterns induced by mitogenic and nonmitogenic anti-Ig antibodies. Whereas the mitogenic, strongly cross-linking, antibody H delta a/1 induced greater levels of tyrosine phosphorylation than did the nonmitogenic antibody FF1-4D5, the pattern of substrate phosphorylation was equivalent. At lower concentrations of H delta a/1, which were still mitogenic, the degree of phosphorylation that was induced was similar to that induced by high concentrations of FF1-4D5. Both antibodies stimulated comparable increases in the kinase activity of the three src-related kinases present in normal B cells and linked to the IgR, i.e., Blk, Fyn, and Lyn. These results suggest that the extent of tyrosine kinase activation is proportional to mIg cross-linking, that induction of B cell DNA synthesis may require little tyrosine kinase activation, and that activation of tyrosine kinase per se does not necessarily lead to B cell DNA synthesis.
Brunswick
M
M
Laboratory of Cell Biology, Food and Drug Administration, Bethesda, MD 20892.
Burkhardt
A
A
Finkelman
F
F
Bolen
J
J
Mond
J J
JJ
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D004789:Enzyme Activation; D007072:Immunoglobulin D / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008811:Mice, Inbred DBA; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism* / Q000502:physiology; D014443:Tyrosine / Q000378:metabolism
D000888:Antibodies, Anti-Idiotypic; D007072:Immunoglobulin D; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases