In more detail, they described that: (i) spontaneous CALRmutant-specific CD4+ T lymphocytes (Th1) are readily detectable in the peripheral blood of many MPN patients; (ii) ex vivo cultured, Th1 cells specific to CALR C-terminus mutations, as well as JAK2V617F-specific CD8+ T lymphocytes, can recognize and eliminate either CALR or JAK2 mutants, respectively, in a mutation-restricted manner. Here, CD4 is linked to myeloproliferative disorder.