Lymphocytic Response to Tissue Transplantation 103 



It remained, however, for the work which will be described below to 

 demonstrate experimentally that the cells of the regional lymph node were 

 indeed capable of carrying out such immunologic reactions. The studies 

 referred to are those involving the transfer of lymph node cells from an 

 immunized or sensitized animal to a normal animal of the same species, a 

 technique which has recently been used to a considerable extent in the eluci- 

 dation of various immunologic phenomena. In the general pattern of these 

 studies, lymph nodes or spleens have been removed from animals (donors) 

 injected with antigenic materials. The lymph nodes or spleens have then 

 been teased apart, and the cells thus released have been transferred to fresh 

 homologous animals (recipients), which have then been examined for the 

 appropriate immunologic reaction — hypersensitivity, humoral antibody, or 

 resistance to transplanted tissue. 



In studies involving a wide variety of antigenic substances, the data re- 

 ported on cytologic examination of the suspensions of transferred cells have 

 been fairly similar. In the reports of Chase 16 on suspensions of guinea pig 

 lymph node cells, of Mitchison 17 on analogous cells from mice, and of Rob- 

 erts and Dixon 18 and of Harris and colleagues 19 on rabbit lymph node cells, 

 the average percentage of cells of the lymphocytic series in the suspensions 

 were ^95, >95, 85, and 99, respectively. In connection with the cytologic 

 composition of suspensions of transferred lymph node cells, it should 

 be pointed out that Roberts, Dixon, and Weigle 20 and, more recently, 

 Holub 21 have examined recipients' tissues at the sites of intramuscular and 

 intraperitoneal injection of lymph node cells, respectively, and have found 

 accumulations of plasma cells there, at about the same time as that of appear- 

 ance of antibody in the serum. It was not possible in these studies to deter- 

 mine whether these plasma cells were the result of conversion of the trans- 

 ferred lymph node cells or of infiltration of host tissue cells. In the study by 

 Roberts and colleagues, 22 there was a definite correlation between the pres- 

 ence of plasma cells and the appearance of antibody, but in the study by 

 Holub, some plasma cell accumulation was found at the site of injection of 

 lymph node cells even if these had not been incubated with antigen prior to 

 transfer so that no antibody appeared in the serum of the recipient. 



Lymph Node Cell Transfer Studies of Hypersensitivity and Antibody 

 Formation 



Before describing the studies that have been carried out with transferred 

 lymph node cells in relation to tissue transplantation immunity, the im- 

 munologic potency of such cell suspensions will be indicated by a brief 

 resume of some of the recent literature on lymph node cell transfer in rela- 

 tion to hypersensitivity and to the production of classic serum antibodies. 



The technique of lymph node cell transfer received its recent impetus 



