SEROLOGIC REACTIONS TO SKIN HOMOGRAFTS OF VARIOUS SIZES IN THE RAT *

Althouph i t has been recently established that massive skin homografts extending over one-third of the body surface of the recipient rat survive longer than small little is known of the magnitude of the immunological response to these massive skin homotransplants. I t was suggested in a recent study4 that the prolonged survival of massive grafts might be due to antigenic “overloading” with consequent immunologic unresponsiveness. Ballantyne and Converse4 noted that second-set massive skin grafts in recipients previously sensitized by a first-set graft from the same donor exhibited prolonged survival, instead of undergoing accelerated rejection. It was further shown that massive grafts in adoptively immunized rats were not appreciably influenced by the passive transfer of sensitized regional lymph node cells, whereas small skin grafts in similarly conditioned animals underwent an accelerated homograft rejection reaction. One parameter of the immune response which is accessible to investigation and measurement is the cytotoxic activity in the sera of graft recipients. In this study, skin grafts have been exchanged between two widely unrelated isogenic rat strains (brown Norway and albino Lewis) and the antibody titers achieved by recipients of small, large, and massive grafts have been compared.