Xid and Xid-like immunodeficiencies from a signaling point of view.

The analysis of Btk-associated molecules and ligand-induced Btk phosphorylation has suggested the existence of a complexed Btk-associated signaling network involved in the activation of B lymphocytes and mast cells. Recent gene targeting experiments have revealed protein kinase C betaI/II (PKCbetaI/II) as a critical component of the Btk-dependent signaling chain and have highlighted a potential role for the Btk-PKCbetaI/II interaction in the amplification of B cell receptor mediated signaling.