Specificity of cell-mediated transplantation reactions: II. Studies with a sensitive assay of cell-mediated cytotoxicity

To study the specificity of transplantation immunity in vitro the capacity of two aggressor cell populations from allografted mice to destroy target cells obtained from a panel of strains having different H-2 types was assessed. ⁵¹Chromium-labelled macrophages were found to be suitable target cells to allow for quantitative comparisons of cytotoxicity. Spleen cells from skin-grafted mice lysed only target cells of strains which shared at least one H-2 region (K or D) with the donor. By contrast, non-adherent peritoneal exudate cells, produced as a consequence of ascites tumour allografts, exhibited a cytotoxic potential approximately 16- to 32-fold greater than the above spleen cells and were capable of lysing third-party target cells of strains having disparity with the graft donor at both H-2 regions. The difference between the two systems appears to be quantitative. These findings appear to reconcile previously conflicting observations, and suggest minimal or no participation of public H-2 specificities in cell-mediated reactions.