Abnormalities in the T cell receptor Vδ repertoire and Foxp3 expression in refractory anemia with ringed sideroblasts

Immune dysregulation has been implicated in myelodysplastic syndrome (MDS) pathogenesis. Refractory anemia with ringed sideroblasts (RARS) is a low-risk subtype of MDS. Our previous study has reported an abnormal γδ T cell receptor (TCR) repertoire in patients with intermediate or high-risk MDS. To characterize the status of T cell immunity in RARS, we investigated the distribution and clonality of the TCR Vδ repertoire and the expression of Foxp3 in patients with RARS. The number of expressed Vδ subfamily members in the RARS group (4.8±2.25) was significantly lower than that in the control group (7.6±0.52, p=0.0012). A significantly lower expression frequency for the Vδ4 (p=0.007), Vδ5 (p=0.0049) and Vδ7 subfamilies (p=0.0225) could be detected in the RARS group. The most frequent clonally expanded T cell subfamily member in the RARS group was Vδ7 (100%, 3/3). Foxp3 mRNA expression was significantly lower and higher than that in the controls in 60% and 40% RARS patients, respectively. In conclusion, marked restriction of the TCR Vδ subfamily expression pattern and great heterogeneity in Foxp3 expression were characteristics found in RARS. These results provide data regarding the immunodeficiency and immune reactive characteristics of patients with RARS, which may provide a basis for immunotherapy options.