RESUMO
In order to study circulating substances which could be involved in uremic immunodeficiency, the activity of plasma and plasmatic fractions of different molecular weight MW (A and B) from 12 patients with chronic renal failure (CRF) and 12 normal subjects (N) was assayed in vitro on PHA stimulated normal lymphocyte cultures. Plasma from CRF patients inhibited lymphoproliferation compared to normal plasma activity (mean +/- SD: 9,990 +/- 3,980 cpm vs. 22,163 +/- 3,054 cpm; p < 0.001). Nevertheless, the corresponding plasmatic fractions failed to induce similar effects. Both normal fractions showed inhibitory effects on proliferation while most of the CRF fractions allowed greater cellular proliferation than the former. The dose-response curves showed that all the normal fractions contained inhibitor(s) whose effect decreased with increasing dilution. Most of the B normal fractions also produced stimulatory effects when they were diluted between 1:5 and 1:25. Variable dose-response curves were obtained in the presence of CRF fractions. However, the lack of inhibitory activity in 9 of 12 patients and the stimulatory effects produced by several A-CRF fractions suggest qualitative differences between CRF and normal fractions. Present findings demonstrate inhibitory and stimulatory activities in the normal fractions which might be due to immunomodulator substances. Disorders in this immunomodulator system could be responsible for the immunodeficiency described in CRF patients.