The role of thrombopoietin in post-operative thrombocytosis

Thrombopoietin (Tpo), the main regulator of thrombocytopoiesis, is a probab le candidate to play a role in the increase in platelet counts that is freq uently seen after surgery. In the current study, serial blood samples of pa tients that underwent major surgery were analysed with respect to Tpo kinet ics, platelet turnover and inflammatory cytokines. Platelet Tpo content and plasma Tpo levels rose before platelet counts increased, suggesting that T po was indeed responsible for the elevation in platelet counts. In addition , an increase in interleukin 6 (IL-6) levels, but not in IL-11 and tumour n ecrosis factor alpha levels, was seen before the rise in Tpo concentration. In vitro, IL-6 was shown to enhance Tpo production by the HepG2 liver cell line. Thus, increased Tpo levels after surgery, possibly resulting from en hanced Tpo production under the influence of IL-6 or other inflammatory cyt okines, are involved in an enhanced thrombocytopoiesis.