SESSILE AND HUMORAL ANTIBODIES 217 



Chutna and Pokorna (1961). In cases where the transplanted 

 tissue is acutely susceptible to the cytotoxic action of immune 

 serum, such as leukaemias, spleen and lymph node cells, or bone 

 marrow, the relevance of humoral antibody to primary graft 

 destruction is more obvious. But cellular sensitization un- 

 doubtedly occurs, and if the experimental conditions are unfavour- 

 able to the host, cellular as well as humoral forces may be 

 necessary in order to achieve the rejection of such tissue. Gorer 

 (1958) describing the histology of the breakdown of E.L.4, a 

 C57BL leukaemia, when transplanted subcutaneously to incom- 

 patible hosts, states that although extensive graft destruction is 

 visible well before cellular infiltration occurs, invading histiocytes 

 are quite capable of destroying any leukotic cells which remain. 

 Amos (i960) has made similar studies upon both E.L. 4 and L1210 

 transplanted to the peritoneal cavities of foreign hosts. This site is 

 considerably more propitious for the growth of these tumours, 

 and it is noteworthy that in these circumstances the host cellular 

 response fulfils a more decisive role. It seems therefore reasonable 

 to consider these two aspects of a host response to be comple- 

 mentary, and the efficiency of any one particular pattern of 

 response would depend upon the relative proportions of the two 

 elements and the vulnerability of the target at the time and site of 

 exposure. 



Theoretically, cellular and humoral factors might act indepen- 

 dently of each other, producing an additive effect upon the graft, 

 or they might act synergically. Although the ultimate fate of the 

 entire graft could be the same in both cases, synergic action implies 

 co-operation between components in the destruction of the same 

 target cell. Some experiments have been performed at the late 

 Dr. P. A. Gorer's laboratory with the purpose of investigating the 

 interrelationships of immune cells and sera. The first of these 

 have been briefly described (Batchelor, Boyse and Gorer, i960; 

 Batch elor, 1962), Four groups of mice were grafted subcutan- 

 eously with a standard suspension of an incompatible ascites 



