Significantly reduced regulatory T cell population in patients with untreated multiple myeloma.

Increases in regulatory T-cells have been demonstrated in hematological malignancies but conflicting results have been reported in multiple myeloma (MM). In this study, we report a decrease in frequency of regulatory T-cells as well as reduced expression of FoxP3 in untreated MM patients which increased significantly after treatment. Regulatory T-cells of MM patients exhibited immunosuppressive activity in an in vitro assay. Reduced regulatory T-cells in untreated MM patients which increased after treatment with thalidomide, suggests the analysis of treated and untreated patients as a single cohort as cause of conflicting results in earlier studies on regulatory T-cells in MM.