COMMON VARIABLE IMMUNODEFICIENCY ASSOCIATED WITH MYELOCATHEXIS AND ALTERED MEMBRANE SODIUM-PROTON ANTIPORT

Alterations in protein kinase C (PKC) activity have been implied in th e pathogenesis genesis of common variable immunodeficiency (CVID). We analyzed amiloride-sensitive red blood cell Na+/H+ exchange (sodium-pr oton antiport, SPA) and its response to protein kinase stimulation in a patient with CVID. Compared with healthy subjects or patients with s epsis, a unique pattern of SPA activation has been shown. The patient' s SPA was decreased and unresponsive to PKC stimulation, whereas stimu lation by insulin, a tyrosine kinase activator, restored SPA activity. An alteration of serine-threonine phosphorylation is suggested as a p ossible mechanism for the immune failure.