Suppression of skin allograft rejection by post-transplantation administration of specific anti-lymphocyte serum

Abstract

An heterologous anti-lymphocyte serum ALS(I-GR), was raised in rabbits by immunization with draining lymph node cells of AKR mice which had rejected DBA/2 skin allografts. Treatment of AKR mice with this ALS on the 4th day after DBA/2 skin grafting, significantly prolonged the survival of the graft in comparison with that in allografted mice treated with normal rabbit serum. In contrast, ALS prepared against unsensitized lymph node cells was found to be ineffective when administered after transplantation. A further prolongation of allograft survival was obtained when ALS(I-GR) was administered to recipients on days +4 and +7. ALS(I-GR) seemed to specifically suppress the rejection of DBA/2, but not of C57 BL/6 skin grafts. The suppressive action of ALS(I-GR) was not due to cross reactive (anti-DBA) antibodies and was probably directed against idiotypic determinants on antigen-stimulated cells.