DISCUSSION 39 



cells, or with the antigens in an immunogenic form but with a different 

 genetic specificity to see if they will then immunize ? Something which 

 I would like to interpret as a recombination experiment has been done 

 in the case of the tubercuhn reaction and the homograft reaction. 

 Tuberculin injected alone doesn't provoke cell-bound antibody, but 

 if it is fed first to macrophages and these are then transferred to a 

 foreign guinea pig that does provoke the formation cf cell-bound 

 antibody, 



Barrett: I can't let all this go without protesting. It seems that a great 

 many people when studying the red cell find in their system results 

 which lead them to the conclusion that the erythrocyte is not antigenic, 

 in the sense of being able to provoke transplantation immunity in the 

 general sense of that term. My laboratory does not yield this type of 

 result : I find that, not only is the red cell a highly potent antigen for the 

 generation of transplantation immunity, but so also are the carefully 

 washed stromata of rell cells ; they are specific, they are highly anti- 

 genic, they are potent in relatively small doses. 



Medawar: What strains are these. Dr. Barrett ? 



Barrett: I ordinarily have used DBA/2 as the donor and BALB/c as 

 the recipient. I have also done it with C3H as the donor, and Dr. E.J. 

 Breyere has done it with rats. 



Davies: DBA/2 and BALB/c only differ at H-3 whereas C3H as 

 donor would give H-2 differences also. 



Barrett: Yes, but these results do not depend upon the compatibility 

 at H-2, If the animal is compatible at H-2 one sees transplantation im-^ 

 munity but no haemagglutinins. If they are not compatible at H-2 then 

 one may see both. 



Hasek: Has anyone tried to estimate the presence of sex antigen on 

 red cells? In our laboratory T. Hraba has done some experiments 

 using ^^Cr-labelled erythrocytes in C57BL mice, and he cannot find 

 accelerated elimination of red cells of male and female in preimmunized 

 animals, so it seems that this antigen is not present. 



Silvers: We have attempted to induce tolerance of the Y factor with 

 red cell preparations. Whereas as few as 200,000 leucocytes will con- 

 sistently induce tolerance of the Y factor on inoculation into neonatal 

 female recipients, the results with much higher dosages of erythrocyte 

 preparations are extremely variable. As many as 100 million red cells 



