Quantitative studies on tissue transplantation immunity. I. The survival times of skin homografts exchanged between members of different inbred strains of mice

Abstract

Skin homografts do not long survive their transplantation between members of different inbred strains of mice. The intensity of the reaction which homografts elicit from their hosts may be measured in terms of their median survival time (MST), i.e. the time which passes between transplantation and the completion of tissue breakdown in the grafts transplanted to 50% of the experimental subjects. A method of analysis formally similar to that which is used to measure the $\text{LD}_{50}$ of a toxic drug yields the following estimates of the MST's (in days) of homografts exchanged between members of the following inbred strains of mice: $A\rightarrow CBA,11.0\pm 0.3$; $CBA\rightarrow A,10.2\pm 0.3$; $A\rightarrow AU,9.0\pm 0.3$; $AU\rightarrow A,9.1\pm 0.4$; $CBA^{\prime}\text{or}$ $F_{1})\rightarrow WG,9.2\pm 0.2$; $WG(\text{or}$ $F_{1})\rightarrow CBA^{\prime},8.5\pm 0.2$. (The provenance of the strains is described in the text.) The substitution of a segregant $(R_{2})$ for an inbred population of recipients yielded survival times ranging from 10 to 19 days. Homografts exchanged between members of the same strictly inbred strain of mice could not be distinguished from autografts, but incompatibilities (falling short of rejection) became apparent when homografts were exchanged between members of separate sublines which, having arisen from a common breeding pair, stood only eight to twelve generations apart at the time of testing. Difference of sex had no appreciable effect on the survival times of homografts, nor differences of age over the interval 6 weeks to 6 months. Tissue breakdown, once begun, took 3 to 4 days to go to completion. Variations between the survival times of homografts transplanted between members of two given strains are more likely to be due to unavoidable variations of surgical technique, affecting the times at which the grafts make vascular and lymphatic connexions with their hosts, than to any other single cause. A review of the survival times of homografts in members of other species shows that an MST lying between 9 and 12 days may be regarded as characteristic of homografts exchanged between animals of distant genetical relationship.