The biochemical basis of transmembrane signalling by B lymphocyte surface immunoglobulin

The specificity of humoral immune responses is determined primarily at the level of antigen interaction with B lymphocytes which express antigen-specific receptor immunoglobulin. When receptor immunoglobulin is crosslinked by antigen or anti-receptor antibodies there isgeneration and transduction of signals which result in new membrane Ia antigen expression and, in some instances, entry of cells into cycle. Until recently, the molecular basis of signal transduction across membrane immunoglobulins has remained enigmatic. Here John Cambier and colleagues discuss studies which indicate that membrane appears similar to thrombin receptors, muscarinic receptors, al adrenergic receptors and many others in transducing signals via initiation of phosphoinositide hydrolysis, yielding diacylglycerol and inositol phosphates which in turn appear to activate protein kinase and calcium mobilization, respectively.