CD4 and leukemia: In a recent study, epigenetic silencing of class II HLA was shown to be regulated by the PRC2 complex, whose selective inhibition was able to restore HLA class II expression and thus antigen presentation to alloreactive CD4+ T-cells.55 In addition to HLA down-modulation, our transcriptomic analysis of relapsed leukemia showed an increased spectrum of changes of immunoregulatory and immune response proteins, including those involved in HLA peptide presentation.