Downregulation of beta adrenergic receptor expression on B cells by activation of early signals in alloantigen-induced immune response

Previously we described a decrease in beta -adrenergic receptor expression in B lymphocytes as a consequence of in vivo alloimmunization. This decreas e correlates with the highest response of alloantibody production by B cell s. In the present report we examined the participation of intracellular sig nals elicited after alloimmune stimulation. We showed that in vitro stimula tion of B cells with mitomycin C-treated allogenic cells induced a reductio n in the number of beta -adrenoceptors. This downregulation correlated to c hanges in basal and in isoproterenol-stimulated intracellular cAMP levels. We found that calcium mobilization and protein kinase C activation triggere d after direct allogenic stimulation and/or by the action of T cell-soluble factors induced the reduction in beta -adrenoceptor sites. These findings could be of interest to understand the neuroendocrine mechanisms involved i n the regulation of B cell activation. Copyright (C) 2000 S. Karger AG, Bas el.