Studies in xenogeneic graft-versus-host reactions.

Human and murine immunocompetent cells when injected under the kidney capsule of Cyclophosphamide pretreated rats initiate a localized graft-versus-host reaction (GVHR). The cardinal feature of this reaction is the formation of tumorous mass of proliferating donor mononuclear cells that invade and destroy the host renal cortex. This xenogeneic graft-versus-host reaction (XGVHR) is specifically inhibited by antilymphocyte sera (ALS) raised against the donor lymphoid cells. The degree of inhibition of ALS is proportional to the number of donor lymphocytes injected as well as the amount of antilymphocyte serum given to each recipient. In addition, it was found that the capacity of antilymphocyte sera to inhibit this XGVHR correlated with their ability to inhibit the rejection of skin allografts. In other words, the capacity of ALS to inhibit this XGVHR does correlate with their immunosuppressive potency. Xenogeneic graft-versus-host reactions produced by human lymphocytes in rats are used as a basis for assaying the immunosuppressive potency of anti-human lymphocyte sera prior to their clinical use