Ariations in rabbit antimouse lymphocyte sera caused by lymphocytes of differing origins in the immunizing inocula

Rabbit antisera against mouse lymph node (ALS), thymus, and immune lymph node (ALS-immune) were tested by skin allograft survival with and without X-irradiation, by H-2 hemagglutination, and by leukoagglutination and absorption. Whole body X-irradiation with rads and shielding of spleen, upper thoracic contents, or femur markedly enhanced the effects of 2 i.p. injections of 0.1 ml of antiserum. The mean survival times of allografts were between 12 and 22 days using either the antisera or X-irradiation and shielding separately. There was prolongation up to 70 days when the two were combined, without increasing mortality. Thoracic and spleen groups brought out differences in the effects of ALS and antithymocyte serum on first-set allograft survival. ALS-immune had the most marked effect on third-set allograft prolongation and produced the most profound decrease in H-2 hemagglutinin responses. Leukoagglutination and absorption of the sera also showed differences, suggesting that antigenic differences between lymph node and thymus cell populations in the immunizing inocula could elicit different antibodies.