Thrombopoietin receptor agonists increase splenic regulatory T‐cell numbers in immune thrombocytopenia.

Summary: Thrombopoietin receptor agonists (TPO‐RA) are a valid therapy for immune thrombocytopenia (ITP), due to megakaryocyte stimulation and (poorly characterised) immune‐modulatory effects. The spleen is pivotal in the pathogenesis of ITP, yet little is known on its immune microenvironment and on effects of TPO‐RA on this organ. To address these topics, we analysed 35 spleens removed for primary refractory ITP. Pre‐splenectomy TPO‐RA administration correlated with increased splenic regulatory T cells (Tregs), type 2 T‐helper cells and histiocyte density and with reduced red pulp sinusoids. Surgical outcome was not associated with TPO‐RA administration, other pre‐splenectomy therapies and/or Treg density. In conclusion, TPO‐RA affect the splenic microenvironment, but this has no impact on splenectomy outcome. [ABSTRACT FROM AUTHOR]