Abstract
In the experiments here given, as in those previously reported, normal guinea pig serum, given in amounts of 1 or 2 cc intraperitoneally to C3H mice 1 hour following the implantation of 2 million 6C3HED lymphoma cells in their subcutaneous tissues, always markedly inhibited growth of the lymphoma cells. When 2 cc of the serum was given on the day of implantation and again on the 2 succeeding days the inhibition was regularly complete. In striking contrast, normal guinea pig serum, even when given repeatedly in the largest feasible amounts, had little or no inhibitory effect in vivo on the cells of 7 AKR lymphomas recently transplanted in AKR mice of the line in which they had originated. It manifested only limited effectiveness against the cells of a single AKR lymphoma that had been transplanted during about 2 years in laboratory-bred mice of the line in which it had originated with later transfer to AKR mice of another inbred line. An immune serum, prepared by injecting rabbits with the lymphoma cells of one of the AKR growths together with Freund''s adjuvants, proved moderately to markedly inhibitory for the AKR lymphoma cells when injected intraperitoneally into mice one hour after implantation of the cells in the subcutaneous tissues. Mixtures of the immune serum with normal guinea pig serum were often completely inhibitory. The significance of the findings is briefly discussed.