[Clinical significance of determining serum soluble IL-6 receptor concentration in plasma cell dyscrasias].

It has been proven that interleukin 6 (IL-6) is the key growth factor for myeloma cells in vitro and in vivo. Binding of serum soluble IL-6 receptor (sIL-6R) with IL-6 can promote the biological effects of IL-6. To investigate the significance of serum sIL-6R in plasma cell dyscrasias (PCD), we determined serum sIL-6R concentrations in 62 patients with multiple myeloma (MM), 5 with macroglobulinemia, 1 with mu heavy chain disease and 15 healthy controls by using ligand immunoenzyme assay. The results showed that serum sIL-6R concentrations in macroglobulinemia and MM at stage II and stage III were significantly higher than these in MM at stage I and healthy controls (P < 0.01). Morever, serum sIL-6R concentrations in MM at stage III were higher than those in MM at stage II (P < 0.01). But there were no statistic difference in serum sIL-6R concentrations between normal controls and MM at stage I (P > 0.05). And there were also no difference in serum sIL-6R concentrations among various M-protein classes (P > 0.05). Our results indicated that serum sIL-6R concentration is a useful marker in reflecting disease severity in MM. Its clinical significance in other PCD needs further investigation.