The Effect of Prior Intravenous Injections of Dissociated Epidermal Cells and Blood on the Survival of Skin Homografts in Rabbits

Abstract

A study has been made of the effect of prior intravenous injections of living homologous dissociated epidermal cells and blood-cells on the survival of skin homografts subsequently transplanted from the cell donors in rabbits. These treatments failed to elicit an immune response resulting in the accelerated breakdown of the skin homografts, even when a massive dosage of homologous blood was administered. On the contrary, in a high proportion of animals injected with their intended donors’ epidermal cells it was found that the host’s capacity to react against the skin homografts was abrogated to an extent that actually increased their survival by a factor of 2 or 3. This prolongation of survival is not merely the outcome of the non-specific treatment of a host with epidermal cells as such, since pre-treatment of animals with suspensions of their own epidermal cells was ineffective in prolonging the survival of homografts. This modification in the host’s response was not obtained by the administration of epidermal cell suspensions by other routes; when the cells were injected intradermally a state of immunity was elicited, and their intraperitoneal injection was without demonstrable effect. The injection of living cells was found to be obligatory since cells killed by freezing and thawing before their injection had no effect on the course of the homograft reaction. The injection of homologous blood gave results comparable with those obtained with epidermal cell suspensions, although they were not as consistent. Evidence is presented suggesting that a state of immunity towards grafts of homologous skin may be evoked by prior intradermal injections of epidermal cell washings not containing intact living cells. Possible explanations and affinities of the induced abrogation of a host’s immunological response to skin homografts are discussed, as well as its possible implications.