PRIVILEGED STATUS OF THE SUBCUTANEOUS SITE FOR SKIN ALLOGRAFTS IN RATS

Abstract

Evidence is presented that in rats the subcutaneous site can extend privilege to both major histocompatibility complex (MHC)-incompatible (FI × DA)F₁ → FI and MHC-compatible LEW → FI skin allografts, approximately doubling the median survival time of similar grafts transplanted orthotopically. Unlike graft dosage, “gene” dosage was an important variable in that grafts from (FI × DA)F₁ donors significantly outlived those from DA strain donors. Prior splenectomy of the hosts did not prejudice the capacity of their subcutaneous sites to extend privilege. It was found that the hemagglutinin response incited by subcutaneous grafts was significantly delayed compared with that evoked by similar grafts transplanted orthotopically or intraperitoneally. This observation, coupled with our inability to demonstrate the passage of India ink to regional lymph nodes after its injection into the dermis of established subcutaneous grafts of syngenic skin, is consistent with the concept that poor endowment of the subcutaneous milieu with both blood and lymph vessels is the principal factor underlying its hospitality to allografts.