Electrophoretic and Ultracentrifugal Studies of Rabbit Hemolysins

Normal rabbit serum and antiserum to either sheep red cells (Forssman and isophile) or to heated stromata (Forssman only) were found to be similar in electrophoretic and ultracentrifugal properties. Only quantitative differences in the percentage composition of the serum proteins were found. The Forssman hemolytic antibody accounted for all or most of the activity in both types of antiserum studied. Forssman hemolytic antibody was found to be associated with a large molecular weight globulin (S20 = 18 S) and was found by starch electrophoresis to migrate between the β and γ globulins. The isophile hemolytic antibody was also found to be associated with a large molecular weight fraction, but was electrophoretically located in the γ globulin fraction. The two hemolytic antibodies thus appear to be two distinct proteins.