STUDIES ON HUMAN C'1-ESTERASE. III. EFFECT OF RABBIT ANTI-C'1-ESTERASE ON ENZYMATIC AND COMPLEMENT ACTIVITIES.

Abstract

Anti-C′1-esterase inhibited hemolytic function of whole complement. Studies with the intermediate complexes EAC′1, EAC′1,4, and EAC′4 indicated that most of the antibody activity was directed toward C′1 and further implied the functional participation of C′1-esterase in immune hemolysis. At high concentrations of antibody, some agglutination of complexes which contained C′4 occurred, probably as a result of low titers of anti-C′4 in the antiserum. Anti-C′1-esterase did not inhibit the activity of the complex EAC′1,4,2, a finding consistent with previous work indicating that C′1 was not necessary for hemolysis once C′4 and C′2 had attached to the sensitized cell.