Influence of Intravenous Immunoglobulin Treatment on Thrombopoiesis.

AIM: The mechanisms by which intravenous immunoglobulins (IVIg) result in an increase in platelet counts in most patients with autoimmune thrombocytopenia (ITP) have not yet been fully explained. One of these mechanisms may be related to stimulation of thrombopoiesis. METHODS: A total of 13 adult patients who received IVIg were studied: 11 patients with primary ITP, 1 patient with ITP related to common variable immunodeficiency (CVID), and 1 patient with uncharacterized thrombocytopenia. IVIg (0.5-1.5 g/kg body weight) was administered on consecutive days (days 1-3). Endogenous thrombopoietin (eTPO) was measured prior to and at least 1 day following treatment. In addition, IL-6 was measured in 5 of the treated patients. RESULTS: In 10 of 13 patients, IVIg treatment resulted in an increase in platelet counts. eTPO remained unchanged or elevated in almost all cases where the platelet count remained low (<100 × 10(3)/μ0. In all cases with normal or increased platelet counts (>100 × 10(3)/μ0, the eTPO concentration decreased. Furthermore, IVIg induced IL-6 synthesis in all 5 examined patients. CONCLUSION: Our data indicate that the induction of eTPO synthesis by IL-6 may be a potential mechanism in which IVIg may stimulate thrombopoiesis. Further studies are required to characterize this mechanism.