Immunosuppressive activity of serum from patients with idiopathic nephrotic syndrome.

Serum from 5 patients with idiopathic nephrotic syndrome (INS) inhibited markedly lymphocyte proliferative response with Con A and rosette formation with sheep erythrocytes (E). The inhibitory effect was not due to a cytotoxic activity of INS serum. The expression of the inhibitory activity on Con A response required the preincubation of lymphocytes with INS serum before Con A stimulation and the inhibitory effect was reversed by washing of lymphocytes exposed to INS serum. Furthermore, lymphocytes from INS patients responded normally to Con A. However, the inhibition of rosette formation with E was not reversed by washing of lymphocytes exposed to INS serum. Although the mechanism of the inhibition of immune response with INS serum was not clearly identified, it seems to be an interaction between INS serum and lymphocyte membranes which may cause the modulation of membrane structures or may influence the metabolic events of lymphocytes.