Finally, we found that both CD4+ and CD8+ T cells isolated from fresh BM samples of MPN patients (N = 16) express the PD‐L1 receptor PD‐1, and that this expression is not influenced by the presence of the MPN disease‐driving mutations JAK2, CALR, or MPL (Figures 3C and S8). Here, CD4 is linked to myeloproliferative disorder.