Higher expression levels of the ICP molecules LAG3, PD-L1, TIM-3, Gal9, CTLA4, CD80, CD86 and CD28 as well as the T cell activation marker CD69, but not of PD-1 and PD-L2 were detected in MPN samples compared to nnBM (Supplementary Fig. S6B–D). Here, CTLA4 is linked to myeloproliferative neoplasm.