Experimental murine and primate models for dissection of the immunosuppressive potential of photochemotherapy in autoimmune disease and transplantation.

This paper reviews the results achieved in murine and primate models of autoimmune disease and transplantation. These studies have attempted to clarify the nature and specificity of the response induced by reinfusion of phototreated immunoactive lymphocytes. Results obtained in murine lupus have demonstrated that some of the disease features related to the abnormal proliferation of inducer T cells can be inhibited both prophylactically and therapeutically by exposure to photoinactivated autoimmune splenocytes. Radiolabeling studies performed in normal syngeneic mice have shown that, if immunoactive cells are phototreated and injected, their recirculation pattern is altered, and increased sequestration in the spleen, bone marrow, and kidney is noted. These studies suggest that reinfused, phototreated, antigen-activated lymphocytes may localize in sites where they are available for induction of immune responses. Primate cardiac xenotransplantation models have demonstrated that reinfusion of phototreated autologous leukocytes, administered with cyclosporine A and steroids, mediates enhanced specific suppression of both the cellular and humoral host response to foreign tissue. Taken as a whole, the experimental models suggest that photopheresis may provide a means of inducing specific suppression of immunoactive T cells. This form of therapy may have a role as an immunosuppressive agent in both autoimmune disease and transplantation.