The Journal of Immunology, Vol 147, Issue 5 1463-1469, Copyright © 1991 by American Association of Immunologists

ARTICLES

B cell triggering by bacterial lipopeptide involves both translocation and activation of the membrane-bound form of protein kinase C

L Bosca, C Marquez and C Martinez
Instituto de Bioquimica, Facultad de Farmacia, Universidad Complutense, Madrid, Spain.

B cell activation by the lipopeptide trispalmitoyl-cysteinyl-alanyl- glycine (TPP), the biologically active moiety of bacterial lipoprotein, results in protein kinase C (PKC) translocation from the cytosol to the plasma membrane, as well as a significant increase in the activity of membrane-associated PKC that can be observed by in vitro incubation with TPP of partially purified PKC at calcium concentrations in the range of those prevailing in unstimulated B cells. TPP does not affect either the phosphoinositide turnover or the cytosolic-free calcium concentration, but promotes an increase in the intracellular pH that can be blocked by the PKC-inhibitors staurosporine or H-7. Moreover, incubation of B cells with staurosporine suppressed the proliferative response promoted by TPP at a half-maximum effective dose of 16 nM. Activation by TPP of PKC isoenzymes resolved after hydroxylapatite chromatography revealed that the resulting beta I/beta II isoenzyme was more sensitive than the alpha isoenzyme. These results suggest that TPP might mediate B cell activation via interaction with the membrane- associated fraction of PKC.

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