[Soluble interleukin-6 receptors in the serum in multiple myeloma].

BACKGROUND

Infrequent studies, having been published so far, have brought few, partly contradictory, results on the importance of soluble receptor of Interleukin-6 (sIL-6R) in serum in patients with multiple myeloma (MM). The aim of the study was to find out, if there are applicable relations between the levels of sIL-6R and the values of selected clinical and biochemical indices and the levels of some cytokines in serum.

METHODS AND RESULTS

The authors analyzed a cohort of 50 patients suffering from MM (age median 64 years, range 34-83 years, ratio of men versus women 1.2:1.0). The soluble IL-6R and other cytokines were examined by ELISA assay, clinical stages of the disease were evaluated according to Durie-Salmon and Bataille. Increased values of sIL-6R (> 90 ng/ml) were in 28 (56%) of patients, median value was 87.4 (range 28.3-220 ng/l). Correlation analysis (Pearson test, p < 0.05) proved a statistically significant relation between the levels of sIL-6R and the values of beta 2-microglobulin (S-B2M) and thymidine kinase (S-TK) in serum. There was no relation to the erythrocyte sedimentation velocity, haemoglobin levels, calcium, urea, creatinine, lactate dehydrogenase, albumin, monoclonal immunoglobulin, C-reactive protein, ferritin, IL-1, IL-2, sIL-2R, IL-6, TNF-alfa, and the occurrence of myeloma plasmocytes in bone marrow. No differences were found between the patients with normal values of S-B2M (< 3 ng/ml) and plasmocytes in bone marrow (< 5%) in comparison with the groups of patients with increased values (3-6, > 6 ng/ml and > 20%, respectively). There was no statistically significant relation of the levels of sIL-6R to clinical stages of MM (1-3) and the degree of activity of the disease.

CONCLUSIONS

Increased values of sIL-6R, detected in more than a half of the cohort, were, with the exception of S-B2M, S-TK and massive infiltration of bone marrow by myeloma plasmocytes, in no applicable relation to selected biochemical indices, to the level of some cytokines and to the degree of advancement and activity of the disease.