Comparative Study of Rabbit Hemolysins to Various Antigens I. Hemolysins to Beef Red Cells

Early and late rabbit antiserums to beef red cells were studied by electrophoretic and ultracentrifugal methods. In early serum most of the hemolytic activity against both beef and sheep red cells was associated with a fast-sedimenting fraction (S20 =18 S) which was found by starch zone electrophoresis to migrate in the ~1 globulins. Its mobility appeared to be the same as that found for the yi isophile antibody of antiserum to sheep red cells, but somewhat slower than that of the yi Forssman antibody. In serum obtained after a secondary period of antigenic stimulation, a second antibody was found in the y2 globulins, and was associated with a slower-sedimenting fraction (S20=6 S). In late serum the 72 antibody accounted for about 50 to 75% of the total hemolytic activity. The physical properties of the 72 antibody therefore appeared to be the same as those found with the 72 Forssman and isophile antibodies. No Forssman hemolysins were produced by the beef red cells. In a mixture of anti-Forssman and anti-beef-cell serums, the large Forssman hemolysin was found to migrate electrophoretically at a faster rate than did the beef-cell hemolysins. Furthermore, absorption of antiserum to beef cells with substances known to contain the Forssman antigen did not remove any of the hemolysin activity againstt beef cells. Absorption of antiserum to beef cells with sheep red cells removed about 50% of the activity against beef red cells. Absorption with heated-beef-red-cell stromata had no effect. Beef red cells therefore appear to contain at least two major antigenic groups that are heat labile. Moreover, each of these groups stimulated the production of at least two antibodies, and the relative electrophoretic distribution of the two antibodies was the same in each case. Antiserum to sheep isophile antigen did not lyse beef red cells, nor was the titer of isophile antiserum diminished after repeated absorptions with beef cells. Therefore neither of the two antigenic groups of beef red cells appear to be serologically related to the isophile antigen of sheep red cells, even though the antibodies produced by beef cells appear to be physically related to those produced by the isophile antigen. To account for the activity of beef-cell hemolysins against sheep red cells, it has been postulated that sheep cells contain a haptenic group serologically related, but not necessarily identical, to the haptenic group of one of the two antigenic groups of beef red cells. The findi