Studies on passive haemolysis mediated by antiserum globulin antibodies.

The concurrent action of complement and antiserum globulin (anti-SG) antibodies on red cells coated with an antigen and sensitized with the specific antibodies was studied. The occurrence of haemolysis in such systems is dependent on the haemolytic properties of the anti-SG antibodies used in the test. The haemolytic properties of the immunoglobulins that sensitize the coated cells have no apparent role in the development of the lysis. The method of titration of antibodies by passive haemolysis can be rendered more sensitive and can be applied to detect antibodies that do not fix complement, if a suitable anti-SG serum is permitted to react with the immunoglobulins that have combined with the antigen coating the erythrocytes. Under standard conditions reproducible titrations can be performed to detect 0·009 μg N Ab/ml with an error equal to 10 per cent.