Alloimmune IgG binds and modulates cardiac beta-adrenoceptor activity.
Purified IgG from murine alloimmune sera directed against class I products from the major histocompatibility complex of the mouse, could bind to the beta-adrenoceptors and stimulate contractile activity of myocardium. Immune IgG inhibited the binding of (-) 3H-DHA to beta-adrenoceptors of mouse myocardial membranes behaving as a competitive inhibitor. Moreover, immune IgG induced positive inotropic and chronotropic effects on isolated mouse atria. These effects could be blocked by beta-adrenoceptors antagonists. Data prove that immune IgG directed against specific alloantigens are able to recognize the beta-adrenoceptors and mimic the stimulation of the beta-adrenoceptor agonist.
D000818:Animals; D016275:Atrial Function; D001667:Binding, Competitive; D004306:Dose-Response Relationship, Immunologic; D006325:Heart Atria / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D013268:Stimulation, Chemical
D007074:Immunoglobulin G; D011943:Receptors, Adrenergic, beta