Major histocompatibility complex modulation of beta-adrenoceptor function

Reciprocal interaction between beta-adrenoceptor specific ligand occupancy and alloantibody binding to specific antigens of cardiac and smooth muscle tissues was observed. Interference of alloimmune antibody fixation to both cardiac and oviductal tract preparations by beta 1 or beta 2 selective blockers, respectively, was obtained by means of indirect immunofluorescence assays. Reciprocally, alloimmune IgG and monoclonal antibodies directed to class I H-2 antigens, behaving as beta-adrenoceptor agonists, modified the contractility of both tissues, increasing intracellular levels of cyclic AMP (cAMP). Additionally, alloantibodies were also capable of inhibiting specific beta-adrenoceptor radioligand binding to purified cardiac and smooth muscle membranes. These data suggested a modulation of beta-adrenoceptor function by antibodies directed against H-2 class I histocompatibility molecules, probably through molecular interactions between both structures.