[Interleukin-6, tumor necrosis factor alpha and their soluble receptors in Bence-Jones nephropathy. Possible role in pathogenesis andthe importance in the determination of prognosis in renal insufficiency].
Bence-Jones nephropathy, the most serious form of which is renal failure, is one of the frequent complications in multiple myeloma (MM). Precise pathogenetic mechanism of renal injury remains unclear. Experimental study points to the possible role of some cytokines in the development of this type of nephropathy. We have investigated the levels of interleukin-6 (IL-6), tumour nekrosis factor alpha (TNF-alpha) and their soluble receptors in patients with plasmocytoma. The group comprised 49 patients with plasmocytoma, mostly with MM. Significantly higher levels of IL-6 were found in patients with irreversible renal insufficiency and/or failure (group A-median 13.3 pg/ml, range 3.6-33.3) comparing patients with reversible impairment (group B-median 3.1-range 1.8-38.4) (p < 0.01) and those with normal renal functions (group C-median 2.3-range 0.97-7.41) (p < 0.01). Significant difference was also found between the groups B and C (p < 0.05). Analysis of variance with the use of various factors showed that the correlation between IL-6 and prognosis of renal disease was stronger (p < 0.001) than the correlation between cytokine levels and the clinical phase of MM (p < 0.05). The difference of IL-6 levels between various clinical stages of MM was not significant. The levels of sIL-6R were significantly increased in patients with both reversible and irreversible renal insufficiency comparing the group with unaffected renal functions (p < 0.05 and p < 0.01 respectively). TNF-alpha levels did not differ between all 3 groups of patients, however, significantly increased values of sTNF-R II were observed in group A vs B and group B vs C (p < 0.05). We conclude, that some cytokines, especially IL-6/sIL-6R, could play an important role in development of renal insufficiency in MM or other monoclonal gammapathies. We suggest that IL-6 levels could be predictive factor for renal insufficiency recovery.