Thrombopoietic cytokines and platelet count in multiple myeloma.

Cytokines like interleukin (IL)-6 and IL-1beta are both implicated in multiple myeloma (MM) pathogenesis and megakaryopoiesis. The dynamic interaction between thrombopoiesis and thrombopoietic cytokines in MM may affect platelet (PLT) counts. Sixty-eight patients with MM (30 female, 38 male; median age 58 (40-79), 38 newly diagnosed, 15 in plateau, and 15 relapse and/or refractory patients) and 21 controls were included in the study. Plasma levels of thrombopoietin (TPO), IL-1beta, IL-11 and IL-6 were measured by ELISA. PLT counts were not different between the control group and MM patients with various disease stages and activity. IL-6 and TPO levels were higher in MM patients than healthy subjects (p < 0.001). PLT counts were inversely correlated with TPO (r = -0.566; p < 0.001) and positively correlated with IL-6 (r = 0.263; p = 0.04) levels in MM patients. TPO and IL-6 levels were significantly correlated (r = 0.305; p < 0.001). Disease activity has no effect on plasma cytokine levels. TPO levels were higher in stage III than stage I (p = 0.05) and stage II (p = 0.03) patients in newly diagnosed MM. High TPO levels induced by IL-6 may sustain normal PLT counts despite bone marrow infiltration by plasma cells and decreased PLT half-life.