220 J. R. BATCHELOR AND M. S. SILVERMAN 



illustrates two representative experiments in the series. Compari- 

 son of the growth of BP 8 in otherwise untreated mice with those 

 which received 2-7 milHon sensitized cells in experiment 6/3 or 

 2*2 milHon in experiment 21/3 shows that inhibition of the tumour 

 was clearly observable by the 7th day and even more obvious by 

 the 9th day. This protection afforded by sensitized cells was 

 abolished by serum treatment. In other experiments, higher cell 

 dosages were injected. It became apparent that the antagonistic 

 action of serum could be overcome at these higher cell dosages, 

 and, inconstantly, figures suggesting synergic action between 

 sensitized cells and humoral antibody were obtained. It will be of 

 great interest if this point can be established with certainty. 



The development of the host cellular response was not inhibited 

 by the quantities of serum used in these experiments. There was 

 no significant difference between the host cell counts of the control 

 and serum-treated groups. The ascitic fluid of animals pretreated 

 with sensitized cells and no serum contained fewer host cells as 

 well as the already-mentioned diminished number of tumour cells. 

 This result is only to be expected in view of the smaller volume of 

 ascites in this group. Ascitic fluid removed from the test mice 

 receiving both sensitized cells and isoantisera contained host cells 

 in equal numbers to the untreated controls. These data are in 

 agreement with Gorer's histological observations upon the 

 normal early development of the host response to subcutaneous 

 BP 8 in serum- treated hosts (Gorer, 1958). Since our observations 

 were not carried beyond the 9th day, it is not known whether the 

 host cellular response would have disappeared prematurely. But 

 it was obvious by this time that in the group of mice receiving 

 serum only, despite the presence of large numbers of host 

 reactive cells no effective destructive action on the part of these 

 cells was occurring. By the 9th day in the controls, clumps of dead 

 tumour-host cell aggregates were frequent; in contrast, none were 

 found in the mice treated with serum only. 



Since it is uncertain what role is played by humoral antibody 



