Renal insufficiency is a serious and frequent complication in patients with monoclonal gammapathies, especially with multiple myeloma (MM). Some experimental data suggest that cytokines may be involved in the pathogenesis of myeloma kidney. We have investigated the levels of IL-6, TNF and their soluble receptors in 49 patients with myeloma, mostly with MM. Significantly increased levels of IL-6 were found in patients with irreversible renal insufficiency and/or failure (group C - median 13.3 pg/ml, range 3.6-33.3) comparing to patients with reversible impairment (group B - median 3.1, range 1.8-38.4) (p < 0.01) and those with normal renal functions (group A - median 2.3, range 1.0-7.41) (p < 0.01) and also group B vs. A (p < 0.05). The difference remained significant even when we compared only the patients with stage III (median 2.07) or active phase of MM (median 3.0) of group A with group C (p < 0.01). The levels of sIL-6R were not statistically different between the patients with irrevesible and reversible renal injury, but they were significantly lower in the group with unaffected renal functions. Analysis of variance showed that the differences of IL-6 levels between the troups A, B and C were highly significant (p < 0.001). The correlation between IL-6 and the phase of disease was also statistically significant (p < 0.05) while the differences between clinical stages remained insignificant. TNF levels were similar in all 3 groups, however, significantly increased values of sTNF-RII were observed in group C and B vs. A. Our results point to the possible role of cytokines, especially IL-6, in development of renal insufficiency/failure in MM. The investigation of IL-6 levels may be helpful in the prediction of renal function impairment recovery.

Keywords: renal failure, TNF, sIL-6R, IL-6, mutliple myeloma