Whole blood production of monocytic cytokines (IL-1 beta, IL-6, TNF-alpha,sIL-6R, IL-1Ra) in haemodialysed patients

Background. The production of monocytic cytokines by isolated mononuclear c ells after stimulation by phytohaemagglutinin (PHA) and lipopolysaccharide (LPS) is generally increased in haemodialysed (HD) patients. We performed w hole blood (WB) cultures to evaluate cytokine production by blood cells ins ide their complex cellular and humoral network. Methods. Diluted whole blood from HD patients (collected before dialysis) a nd controls was cultured alone with PHA (2.5 mu g/ml) or LPS (1 and 3 mu g/ ml). Supernatants were collected after 24 and 48 h of culture, and concentr ations of IL-1 beta, IL-6, TNF-alpha, sIL-6R and IL-1Ra were determined by ELISA. Results. The low spontaneous production of IL-1 beta, IL-6 and TNF-alpha in both patients and controls was not significantly modified by PHA. The lowe r dose of LPS (1 mu g/ml) induced a significant but lower increase in produ ction of IL-1 beta, IL-6 and TNF-alpha. in patients than in controls. In co ntrast, while it did not further increase their production in controls, the higher concentration of LPS (3 mu g/ml) still increased their production i n patients to the same level than in controls. The plasma concentrations of sIL-6R were higher in patients than in controls. In both groups, the sIL-6 R concentration did not vary during the culture period whether the cells we re stimulated or not with LPS or PHA. This suggests that the increased plas ma levels of sIL-6R were not produced by blood cells. Despite a similar sig nificant LPS and PHA induced production of IL-1Ra. the IL-1Ra/IL-1 beta rat io was always higher in patients than in controls. Conclusion. Monocytes from HD patients in WB cultures are hyporesponsive to PHA and LPS for their IL-1 beta, TNF alpha and IL-6 production in contrast to isolated monocytes that demonstrate signs of activation. If it reflects the in vivo situation it could partly explain the immune defect in uraemic and haemodialysed patients. Higher sIL-6R/IL-6 and IL-1Ra/IL-1 beta ratios could also participate to the complex immune disturbances of HD patients b y reducing the biological activity of two cytokines playing a major role in the immune and inflammatory network.