Serum levels of IL-6 and its soluble receptor (sIL-6R) in Waldenstrom's macroglobulinemia

Background: Interleukin-6 (IL-6) is a multifunctional cytokine that plays r oles in the immune response, inflammation and hematopoiesis. Serum IL-6 lev els have reported to reflect disease severity and high tumor burden in mult iple myeloma (MM) patients and to correlate with several other laboratory p arameters. Serum-soluble IL-S receptor (sIL-6R) plays an agonist role in IL -6 signaling, enhancing its biological activity tenfold. Purpose Methods: W e measured IL-6 and sIL-6R levels in 11 patients (7 male, 4 female, mean ag e 66.9 yr) with Waldenstrom's macrobulinemia (WM) using a commercially avai lable enzyme-linked immunoassay in order to investigate their biological ro le and to find any possible relationship with disease severity, tumor burde n or response to treatment. Results: Serum IL-6 and sIL-6R concentrations a t diagnosis were significantly higher than in healthy controls (Mann-Whitne y U-test, p < 0.001 and p < 0.01, respectively). Patients who were effectiv ely treated had a significant reduction in IL-6 levels (p = 0.017). With re gard to sIL-6R levels, no specific tendency was observed. In some of the re sponsive patients the levels increased whereas in others they decreased. No correlation was found between IL-6 and sIL-6R levels at diagnosis (p = 0.9 , r = 0.036) or after treatment (p = 0.083, r = 0.3). Conclusions: Our resu lts suggest that IL-6 may be a marker reflecting tumor burden, disease seve rity and response to treatment in WM. With regard to sIL-6R, we believe tha t it does not seem to be of much value, and its role remains to be clarifie d. However, future studies are needed to confirm and further extend the pre sent results.