B cell immunity regulated by the protein kinase C family.

Protein kinase C (PKC) is a family of serine/threonine kinases which mediate essential cellular signals required for activation, proliferation, differentiation, and survival. Several PKC members are expressed in B lineage cells and activated by stimulation of the B cell receptor (BCR), thus suggesting a contribution of PKCs to the B cell-mediated immune response. To understand the individual roles of PKCs for B cell immunity, mice deficient for PKCbetaI/II (PKCbeta) or PKCdelta were analyzed. PKCbeta and PKCdelta play essential but distinctive roles in B cell immunity. In addition to its role in B cell activation and humoral immunity, PKCbeta was recently shown to control NF-kappaB activation and survival of mature B cells. PKCdelta on the other hand specifically regulates the induction of tolerance in self-reactive B cells. Thus, individual PCKs regulate B cell immunity specifically.