CD28 and myelodysplastic syndrome: To determine whether abnormal IFNγ secretion in MDS mice was mediated by IRAK1, we isolated splenic CD4T cells from Mecp2 Dup and WT littermates and cultured them in vitro with anti-CD3 and anti-CD28 antibodies, as well as IL-18 (100 ng/ml), to induce robust IFNγ secretion.