Studies on the reaction of host lymphoid system in homotransplantation. I. Humoral and cellular reactions against the transplanted cells

For the purpose to clarify the relationship between production of humoral antibodies and cellular reactions of the lymphoid system to allogeneic-transplanted cells in mice, a study on cross sensitization was carried out between inbred A(H-2a) and C3H(H-2k) strain mice. The median survival time of skin of C3H transplanted to A (C3H-to-A) was 14.1 ± 1. 4 days, and of A transplanted to C3H(A-to-C3H) was 11.8± 1. 6 days. Repeated A cell injections to C3H induced the formation of humoral antibodies, whereas the C3H cell injections into A did not. In A-to-C3H and C3H-to-A combinations, the immunization induced an increase in white blood cell number in circulating blood successively with the repetition of the antigen injection, and organ weights increased in thymus, spleen, and liver but not in kidney. Weight increases in the organs of A treated with C3H cell injection were less in extent, comparing to those of C3H treated with A cells. Histologic observations revealed that the cellular proliferation in the lymphoid system including plasmocytic responses were obviously predominant in the C3H treated with A cells comparing to those in the A treated with C3H cells. Hemocytoblasts also increased during the immunization in both cases showing no significant differences between the two series of experiments. These cellular reactions were observed not only in the draining lymph nodes but also in the generalized lymphoid tissues. The results of the present study suggest that the definitive factor for producing humoral antibodies is in the differences of the homologous antigenicity between the donor and the recipient but not in the degree of sensitization, and the Dk in H-2 loci is not so strong in antigenicity as to elicit sufficient plasmocytic responses for the formation of humoral antibodies in C3H strain mouse.