Reactions of murine myeloma cells with infectious mononucleosis sera

Reactions of murine myeloma cells with infectious mononucleosis sera were studied by means of cytolysis in agarose gel. Of 75 sera tested, 30 lysed IgM myeloma cells, MOPC-104E. The antibodies responsible for the lysis of the myeloma cells were shown to be different from Paul-Bunnell antibodies and other antibodies found in infectious mononucleosis sera. Three types of antibodies acting upon the myeloma cells were identified serologically on the basis of absorption experiments with bovine erythrocytes, theta-positive murine lymphoma cells and guinea pig kidney cells. Antibodies of the first group could be absorbed with none of these antigens, antibodies of the second group could be absorbed only with lymphoma cells, and antibodies of the third group could be absorbed with any of these three antigens. Evidence was presented that the antibodies under study combine with antigenic cell membrane components of a subpopulation of IgM-producing murine B cells.