PMID: 2107258Mar 15, 1990Paper

Altered signal transduction secondary to surface IgM cross-linking on B-chronic lymphocytic leukemia cells. Differential activation of the phosphatidylinositol-specific phospholipase C

The Journal of Immunology : Official Journal of the American Association of Immunologists
C HivrozC Grillot-Courvalin

Abstract

To further study the mechanisms by which surface Ig triggering activates the inositol phospholipid signaling pathway, we have used B cells from chronic lymphocytic leukemia patients which, as previously described, display two patterns of response upon sIg cross-linking: in one group this cross-linking induces an inositol phosphate release, an intracellular free Ca2+ concentration elevation and a subsequent cell proliferation; in a second group none of these events occur although there is an increased class II Ag expression following anti-mu stimulation as in the first group. We have been able to demonstrate that the phosphatidyl inositol specific phospholipase C (PI-PLC) can be activated in permeabilized B cells from the first group by direct stimulation, with GPT gamma S, of a guanine nucleotide binding (G) protein. In addition, since anti-mu + GTP gamma S stimulate an increased inositol phosphate production in these cells, this suggests that surface Ig cross-linking activates PI-PLC via a G protein. However, in cells from the second group no inositol phosphate is released after GTP gamma S stimulation although PI-PLC can be directly activated by high Ca2+ concentrations. This reflects in these cells, an interruption of the si...Continue Reading

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