Popliteal lymph node assay as a method of investigating H-Y antigen in the rat.

The ability of the popliteal lymph node assay (PLNA) To detect host-versus-graft activity in response to H-Y antigens was investigated in the rat by using presensitized recipients. It was shown that significant popliteal lymph node (PLN) enlargement in response to H-Y-incompatible lymphocytes from syngeneic donors could be obtained in female recipients that had been preimmunized by the weekly i.p. injection of 1 x 10(7) lymphocytes from males of the same strain. In one rat strain, it was also shown that when male recipients had been similarly preimmunized with lymphocytes from females of the same strain, significant PLN enlargement could be obtained in response to lymphocytes from syngeneic females. The results that we obtained using the PLNA are discussed in comparison with those that have been reported when H-Y-incompatible skin grafts have been used to investigate H-Y antigen in the rat. These results indicate that, in the rat, the PLNA provides a useful alternative method for the investigation of H-Y antigen and may also provide a useful means to investigate the response of male rats to lymphocytes from syngeneic females.