PROLONGATION OF SKIN ALLOGRAFT SURVIVAL WITH ANTILYMPHOCYTE SERUM AND SOLUBLE HISTOCOMPATIBILITY ANTIGENS

Abstract

Prolongation of skin allograft survival in rats across a strong histocompatibility barrier (H-1 locus) has been obtained after combined treatment with horse antirat lymphocyte serum (ALS) and soluble donor-type histocompatibility antigen. The donors were injected i.p. with a total dose of 4 ml of ALS on days –1 and +1 ((lay 0 being the day of grafting) followed by a protracted i.v. administration of small doses (300 units) of soluble antigen. Significant specific prolongation of the grafts was obtained in comparison with the control groups treated with either ALS or antigen only. It seems necessary to administer the antigen in a protracted fashion since the same total quantity of soluble antigen injected only twice after transplantation (days 5 and 7 or 9 and 12) did not improve the effect obtained with ALS alone. The fact that lymphocytes from the majority of the “tolerant” animals were shown to be reactive against donor-type antigen (graft-versushost reaction) suggests that the observed unresponsiveness may be attributable to enhancement rather than to tolerance in the classical sense.