PROLONGED SURVIVAL OF SKIN ALLOGRAFTS AFTER INCUBATION WITH RECIPIENT DNA OR RNA

Successful genetic transformation of bacteria and mammalian cells by foreign nucleic acids has been reported several times. Since antigens are specific, it is assumed that they originate in contact with nucleic acids. Skin grafts from A-, CBA-, DBA/2-, and Balb/c-strains of inbred mice were incubated with DNA or RNA extracted from spleen or skin of the prospective recipients and transplanted across the H-1 or H-2 histocompatibility locus. A simple and fast transplantation technique has been developed by which thin ear skin of mice is grafted into two holes which are punched into the recipient's back skin. Variations of the incubation medium, the concentration of DNA or RNA, the temperature, and the length of incubation were tested. Across the H-2 locus graft survival could be prolonged up to 32 days, across the H-1 locus up to 68 days. Longest survival was achieved after incubation for 3 hours at 20°C. in media with the highest concentration of DNA (7.5 mg./ml.) or RNA (7.6 mg./ml.). RNA and DNA extracted from skin appeared to be more effective than those extracted from spleen. The addition of protamine to the incubation medium generally prolonged graft survival. Since RNase and DNase treatment of the medium prevented any prolonging effect, prolongation is assumed to be mediated by the nucleic acids. It is suggested that during the process of incubation small amounts of RNA or DNA enter the graft cells and there induce synthesis of foreign" antigen which replaces or competes with the original antigen. © 1968."