Transplantation of cultured thymic fragments. II. Results in nude mice.

Abstract

Nine nude mice were transplanted with cultured thymic fragments derived from syngeneic (3 recipients) or allogeneic (6 recipients) sources. All transplanted mice survived for periods of up to 8-10 mo. thereafter, at which time they were sacrificed. Weight gain had been progressive and the animals were in excellent health. Four nontransplanted littermates housed in the same cages died at the age of 4 mo. In the nontransplanted mice, the usual deficits of T [thymus-derived] and B [bone marrow-derived] cells were observed. In transplanted mice, normalization of Ig[immunoglobulin]G1 and IgA levels as well as IgG antibodies to sheep erythrocytes and precipitating antibodies to rabbit serum occurred. Lymphocyte counts and Thy-1 bearing cells increased to .apprx. 50% of normal values. Proliferative responses to phytohemagglutinin and concanavalin A, mixed leukocyte reactivity and cell-mediated lympholysis were variably restored from .apprx. 10-100% of normal. Attained responses were the same in recipients of syngeneic or allogeneic tissues and these, in turn, were equal or superior to responses measured in animals transplanted with whole noncultured thymuses. Skin grafts from 3rd party donors were vigorously rejected, whereas those derived from 2nd party (allogeneic thymus donor strain) may have been accepted or slowly rejected. Cultured thymic fragments, consisting primarily of epithelial elements, can effectively repair the thymic deficiency of nude mice. Experiments to data do not indicate that syngeneic tissues enjoy an advantage over allogenic grafts in this restoration procedure.