The humoral responses of haemodialysis patients to antigen challenge.

Twenty-four patients on regular haemodialysis had repeated serum samples tested for lymphocyte cytotoxicity and for factors which inhibit the mixed lymphocyte culture (MLC). It was found that serum with a high urea content did not increase the incidence of inhibition of MLC. In 16 patients on haemodialysis there was inhibition of MLC by autologous serum and the same combinations of lymphocytes were inhibited in repeated tests. The serum from 10 of these patients was also cytotoxic for lymphocytes. Serum from 12 patients was not cytotoxic but 6 of these caused inhibition MLC. It is suggested that inhibition of MLC may be produced by factors which are not specific for HLA. Serum from patients who previously rejected kidney transplants or who had pregnancies or multiple blood transfusions showed increased cytotoxicity, but these factors did not increase the frequency of serum inhibition of MLC. The significance of serum inhibitory factors and cytotoxic antibodies in the early clinical course of 12 cadaver transplants is discussed.