Patients with myelodysplastic syndromes show reduced frequencies of CD4+ CD8+ double‐positive T cells

Even though the expression of CD4 and CD8 on thymocytes is considered mutually exclusive, CD4 + CD8 + double-positive T cells (DP) represent a small subset of T lymphocytes that have been described in the peripheral blood of normal individuals, as well as in some pathological conditions. In particular, an agedependent accumulation of monoclonal DP has been shown in elderly healthy subjects. From the functional point of view, DP are able to act as differentiated effector memory cells with specific antiviral functions.