The effect of uraemic serum and plasma on proliferating cells in vitro

Phytohaemagglutinin (PHA)-stimulated lymphocytes from healthy individuals and a malignant cell-line (K-562 cells) were cultured in a growth medium of 75 per cent RPMI 1640 (Gibco) supplemented with 25 per cent of uraemic serum or plasma obtained after systemic heparinization. Pooled human A Rh+ serum from 3 different donors served as controls. There was a depression of the DNA synthesis in both cell systems measured as uptake of methyl-3H-thymidine when the cells were cultured in uraemic milieu. Systemic heparinization markedly increased the depressive effect of uraemic plasma compared with controls. Heparin added to the growth media in concentrations much higher than those usually present in plasma after systemic heparinization had little effect on the cell proliferation. Systemic heparinization thus appears to induce production of toxic substances in plasma acting on proliferating cells.