Plasma levels of soluble interleukin-2 receptors (sIL-2R) were measured by an enzyme-linked immunosorbent assay in 79 patients with systemic sclerosis (SSc). These levels were significantly elevated in SSc patients, compared with normal controls (mean 2 SEM 866.0 -t 63.6 unitshl versus 293.0 & 20.5; P < 0.001).Soluble IL-2R levels were highest in patients with generalized disease, were strongly associated with mortality (P < 0.001) and inversely correlated with disease duration (P = 0.003), but were not related to sex, age, specific visceral involvement, serologic status, peripheral lymphocyte count, or therapy. Levels of sIL-2R in the supernatants of peripheral blood mononuclear cells were low in patients and controls, and showed comparable increases following phytohemagglutinin stimulation. Exposure of peripheral blood mononuclear cells to laminin did not induce sIL-2R release. Circulating IL-2 levels were comparably low in patients and controls. Our findings suggest the presence of lymphocyte activation in SSc, and further suggest that measurement
T lymphocyte function was analyzed in patients hemodialyzed with ‘high-flux’ polysulfone membranes, which have been reported to improve the patients’ overall clinical condition and well-being. For comparison purposes, patients treated by the use of ‘low-flux’ cuprophane membranes were also studied. Peripheral blood white cell counts, numbers of lymphocytes as well as the numbers of T cells and their CD4 and CD8 subsets were within normal range in both patient groups. The absolute number of B cells was slightly decreased in cuprophane-membrane- but not polysulfone-membrane-treated patients. The proliferative response of T lymphocytes after stimulation with optimal concentration of phytohemagglutinin (PHA) was normal in patients treated with ‘high-flux’ membrane dialysis but significantly reduced in those treated with cuprophane membranes. The generation of interleukin-2 (IL-2) receptor on T lymphocytes after PHA stimulation was normal in the polysulfone-membrane-treated group and slightly impaired in the cuprophane-membrane-dialyzed patients. Production of both IL-2 and interleukin-1, as well as the natural killer cell activity, in patients treated by ‘high-flux’ membrane dialysis were also comparable to controls. The levels of serum β2-microglobulin were significantly elevated in patients-maintained on ‘high-flux’ dialysis membranes but did not reach the levels seen in patients dialyzed by cuprophane membranes. The pY microglobulin at levels seen in patients on cuprophane dialysis had no effects on activation and proliferation of control lymphocytes in vitro. These results suggest that impaired functional responses of T lymphocytes seen in end-stage disease patients on prolonged hemodialysis with cuprophane membranes are not seen in similar patients hemodialyzed with polysulfone membranes.
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