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

Abstract

Previously we described a decrease in β-adrenergic receptor expression in B lymphocytes as a consequence of in vivo alloimmunization. This decrease correlates with the highest response of alloantibody production by B cells. In the present report we examined the participation of intracellular signals elicited after alloimmune stimulation. We showed that in vitro stimulation of B cells with mitomycin C-treated allogenic cells induced a reduction in the number of β-adrenoceptors. This downregulation correlated to changes in basal and in isoproterenol-stimulated intracellular cAMP levels. We found that calcium mobilization and protein kinase C activation triggered after direct allogenic stimulation and/or by the action of T cell-soluble factors induced the reduction in β-adrenoceptor sites. These findings could be of interest to understand the neuroendocrine mechanisms involved in the regulation of B cell activation. Copyright ©2000 S. Karger AG, Basel.