INTERACTION OF A SERUM INHIBITOR OF C' I-ESTERASE WITH INTERMEDIATE COMPLEXES OF IMMUNE HAEMOLYTIC SYSTEM .1. SPECIFICITY OF INHIBITION OF C'I ACTIVITY ASSOCIATED WITH INTERMEDIATE COMPLEXES

  • 1 January 1962
    • journal article
    • research article
    • Vol. 5  (2) , 222-+
Abstract
An investigation is described of the interaction of a highly purified human serum inhibitor of C[image] I-esterase with various intermediate complexes of sensitized sheep erythrocytes and human or guinea-pig complement. The inhibitor reacted with and blocked specifically the activity of C[image] I on these complexes. There was a direct correlation, by several criteria, between the ability of the inhibitor to block esterolytic activity of C[image] I-esterase in solution and its ability to inhibit C[image] I activity on the intermediate complexes, implying the participation of C[image] I-esterase in immune haemolysis. Prior interaction of the inhibitor with complexes between sensitized erythrocytes and C[image]l and C[image]4 prevented subsequent reaction of these complexes with C[image]2. However; once the complex between sensitized erythrocytes and C''l, C[image]4 and C[image]2 had been formed, the inhibitor was no longer effective in preventing haemolysis. These data suggested a biochemical function for C[image]I-esterase in reactions involving C[image]4 and C[image]2 but not in further steps leading to immune haemolysis.,.