Phagocytosis in subacute bacterial endocarditis. Localization of the primary opsonic site to Fc fragment.
The opsonic properties of immune gammaG-globulins isolated from patients with chronic septicemic conditions, principally subacute bacterial endocarditis were studied. Opsonic capacity as well as complement-fixing properties of gamma-globulins appeared to be closely associated with integrity of Fc structures. Progressive pepsin digestion of immune gammaG-globulins, as monitored by successive loss of Gm(a) and Gm(b) antigens, abolished opsonic activity. Colostral gammaA, containing agglutinating antibacterial antibodies but no demonstrable complement-fixing activity, was devoid of opsonic capacity. Reduction of gamma-globulin opsonins with 0.01 or 0.1 M mercaptoethanol progressively abolished opsonic activity in parallel with loss of ability of treated gamma-globulins to fix complement with bacteria. Treatment of gamma-globulin opsonins with 0.01 M sodium metaperiodate also produced complete loss of opsonic capacity in parallel with loss of Gm(b) Fc antigens. These findings, together with antiopsonic effects demonstrable with anti-gamma-globulin factors showing primary reactivity with Fc structures, indicate that the opsonic property of immune gamma-globulins requires the participation of structures integral to the Fc region of gamma-globulin.
D000372:Agglutination Tests; D001665:Binding Sites; D003126:Colostrum; D003168:Complement Fixation Tests; D004698:Endocarditis, Subacute Bacterial / Q000503:physiopathology*; D006801:Humans; D007122:Immunoelectrophoresis; D008623:Mercaptoethanol / Q000494:pharmacology; D009895:Opsonin Proteins / Q000032:analysis*; D010434:Pepsin A / Q000494:pharmacology; D010504:Periodic Acid / Q000494:pharmacology; D010587:Phagocytosis / Q000502:physiology*; D005719:gamma-Globulins / Q000032:analysis*
D009895:Opsonin Proteins; D005719:gamma-Globulins; D010504:Periodic Acid; D008623:Mercaptoethanol; D010434:Pepsin A