Platelet-derived TGF-β1 and Treg maintenance in a murine model of ITP.

Studies suggest that platelet-derived transforming growth factor (TGF)-β1 is critical to immune thrombocytopenia tolerance via regulatory T-cell (Treg) modulation, but their implausibly high TGF-β1 levels likely reflect ex vivo artifacts. We could not confirm platelet-derived TGF-β1-driven Treg deficiency using knockout mice; remission maintenance likely involves extra-platelet TGF-β1 sources.