ELEVATION OF SERUM THROMBOPOIETIN PRECEDES THROMBOCYTOSIS IN KAWASAKI-DISEASE

dKawasaki disease (KD) is an acute systemic vasculitis causing coronar y arterial aneurysms and myocardial infarction in young children. Prom inent thrombocytosis with increased megakaryocytes develops during the convalescent period. To clarify the mechanisms of thrombocytosis, we studied serum levels of thrombopoietin (TPO) and other thrombopoietic cytokines in 40 patients with KD (149 samples) and 106 age-matched con trols using ELISA. TPO values in the controls were 1.94 +/- 0.69 fmol/ ml (mean +/- SD) with a 95% reference interval of 0.85 to 3.27 fmol/ml . In the first week of KD, platelet counts were normal but TPO values increased (similar to 15.5 fmol/ml). TPO levels peaked on day 6+/-2 at 5.94 +/- 2.64 fmol/ml and then fell gradually. When platelet counts p eaked in the second to third weeks, TPO levels were still high or comp arable with the controls. TPO levels in KD patients with normal platel et counts were significantly higher than control levels. Interleukin ( IL)-6 levels in the first week rose, but neither IL-11 nor leukemia in hibitory factor was detectable. These results suggest that TPO contrib utes to thrombocytosis in KD in conjunction with IL-6 and TPO producti on may be enhanced during the acute phase.