2l8 J. R. BATCHELOR AND M. S. SILVERMAN 



sarcoma, BP 8. The control group received no additional 

 treatment, but the remaining three groups were given either a 

 subefFective dose of isogenic lymph node cells "sensitized" 

 against BP 8, or an amount of host-strain anti-BP 8 immune 

 serum calculated to produce enhancement, or a combination of 

 the "sensitized cells" and serum. In contrast to the other groups, 

 marked inhibition of tumour groMrth occurred in the animals 

 receiving both the subefFective dose of sensitized cells and serum. 



While these results suggested that cells and serum might act in 

 harmony, the experimental system used v^as not ideal for an 

 exact analysis of the mechanisms involved. The present authors 

 therefore carried out a series of similar experiments in which BP 8 

 was transplanted intraperitoneally to incompatible recipients. The 

 C3H ascites sarcoma, BP 8, is a suitable tumour for this type of 

 study as it has a distinctive microscopic appearance, and its growth 

 at this site is uncomplicated by plaques of solid neoplasm. Accurate 

 counts of tumour and host cells are therefore possible, and viability 

 can be assessed. 



Groups of 6 BALB/c or (BALB/c x C57BL)Fi hosts were 

 given identical intraperitoneal injections of BP 8 in doses between 



4 and 6 million cells. Control mice had no further treatment. The 

 groups receiving serum were injected intraperitoneally 2-3 hours 

 before tumour inoculation with BALB/c or (BALB/c x C57BL)Fi 

 anti-BP 8 serum. Doses are indicated in Table I, but in all cases 

 were such as to be incapable of causing suppression of tumour 

 growth if given alone. Enhancement was usually observed. 

 Isogenic sensitized cell suspensions were prepared from lymph 

 nodes draining the site of a subcutaneous implant of BP 8 injected 



5 days previously. To obtain the maximum yield of sensitized 

 cells these mice were injected subcutaneously in 6 places and the 

 draining inguinal, axillary and brachial nodes on both sides 

 harvested. The animals inoculated with sensitized cells received 

 them mixed with the tumour suspension. As in the previous 

 experimental design, some mice received serum or sensitized cells 



