Isolation of an Immunosuppressive Fraction in Ultrafiltrate from Uremic Sera

Abstract

An improved purification method for isolating an immunosuppressive fraction from uremic ultrafiltrates was described. Lyophilized ultrafiltrates were fractionated on Sephadex G-15 and the active fraction was further purified using high-performance liquid chromatography. The inhibitory effect of eluates on in vitro lymphocyte proliferation was assessed at the different steps of purification. Results obtained after enzyme treatment suggested that the substance(s) responsible for the immunosuppressive activity is (are) of peptidic nature. This peptide appears to be different from the other peptides previously reported, which have a much lesser activity in the lymphocyte proliferation assay.

In vitro Effect of PTH on Normal T Cell Functions

“…While uremic lymphocytes have been reported to exhibit impaired [8], normal [9] or enhanced [10] blast formation, it is generally accepted that uremic serum plays a predominant role in inhibiting this function [11]. However, the nature of this inhibitory activity has not been clarified, though several immunosuppressive frac tions were isolated from uremic sera or dialysate [12], A prominant biochemical abnormality in uremic pa tients is secondary hyperparathyroidism. Parathyroid hormone (PTH) has been shown in the last decade to be a major uremic toxin, underlaying many of the uremic syndromes [13].…”