l82 DISCUSSION 



point that we were trying to make is that such tumour emboH within 

 the lymph nodes are much more susceptible to the host's response than 

 the original tumour graft. This might apply also to metastasis of 

 primary tumours. 



Amos: I think it is very likely that transplanted tumours do carry 

 antigens which are not particularly effective in ehciting immunity. 

 When Gorer and I put E.L.4 into back-cross mice, the tumour killed 

 rather more than half the back-cross, but if we gave them a little whole 

 blood beforehand, most of the adults were able to reject the tumour. 

 This corresponded to something like the presence of 5 antigens. So the 

 tumour cells were in a condition in which they did not normally induce 

 immunity but they were susceptible to it. 



Secondly, we often found it quite difficult to show absorption of 

 antibody with some of these non-specific tumours, especially the 

 Ehrlich and the Ehrhch clones. Now it is often difficult to elicit 

 isoantibody against these, but if one does, it can have quite a high titre. 

 The tumour cells themselves are extremely inefficient at absorbing the 

 antibody, and I have not seen the other sort of situation. 



Feldman: As to the point about the capacity of such tumour cells to 

 absorb isohaemagglutinins, one of the main differences between the 

 examples which you have just quoted and these cases is that the Ehrlich 

 tumour has long forgotten its genetic origin, whereas all these tumours 

 with which we are dealing are recently established tumours which have 

 been produced by benzpyrene and therefore would have much more 

 of the original isoantigens than the type which you have described. 



Amos: I would dispute this. Certainly the E-2 clone has remarkably 

 remembered its origin : it does have a number of fairly characteristic 

 antigens, which we can demonstrate are not derived from the strain in 

 which it is being carried. The tumour has been passed through 20 trans- 

 plant generations in DBA/2 and C3H hosts, and was still capable of 

 giving virtually the same response in 129 mice. 



Feldman: Even a partial loss of certain components among the various 

 isoantigens will result in a lack of absorption, whereas complete 

 absorption can take place only when all the components are there. 



Amos: Another point is that some time ago Dr. Mirand and I did 

 some experiments in which we transplanted DBA/2 lymphoma into 

 the chorioallantoic membrane of chicks. After one chick embryo 



