Genetic control of variability in responses to class-I-antigen disparate thyroid grafts

Thyroid graft transplantation was performed between mice of congenic strains that differ in the K or the D region. Five donor-recipient pairs of different strains were tested in each combination, and the contributions of the K and the D region gene products to thyroid graft rejection were compared. We found that thyroid cells express immunogenic H-2K and H-2D molecules, as measured by their ability to induce strong graft rejection responses. Great variability in the percentage of grafts rejected was found, however, among different pairs of congenic mice. Across D region disparities, for example, the results varied from acute thyroid graft rejection in all B10 (D^b) recipients transplanted with B10.HTI (D(d)) thyroid grafts, to prolonged survival of all thyroid grafts of B10.S (D(s)) donors transplanted into B10.2(26R) (D^b) recipient mice. To test the involvement of different genes in regulation of the immune response against class-I-disparate thyroid grafts, a D region disparity was chosen. A minimum of three different genes were found to affect the response. These genes include a non-H-2 background gene and two genes in the K/I and the D regions of the H-2 complex. The possible mechanisms by which structural and regulatory genes might affect the rejection of class-I-disparate thyroid grafts are discussed.