gamma delta regulatory T cells are able to inhibit the activation and function of T cells involved in antigen-specific immune responses. This study aimed to investigate the potential role of gamma delta regulatory T cells in inhibiting anti-tumor immune responses in patients diagnosed as multiple myeloma (MM). We measured the levels of gamma delta T cells, the distribution and clonally amplified TCR V gamma and V delta T cells in peripheral blood of healthy donors, patients recently diagnosed with MM, and MM patients in remission cohorts. In addition, we evaluated the ability of gamma delta regulatory T cells to inhibit the proliferation of CD4-FCD25- T cells and detected the expression of immunoregulatory-associated molecules. We found that the levels of gamma delta regulatory T cells from the peripheral blood in patients of MM were significantly higher than those in healthy donors. Comparison of gamma delta T regulatory cells function in MM and healthy donors showed similarly inhibitory effects on the proliferation of T cells. Additionally, TLR8 expression level increased significantly in MM patients compared to healthy donors, while the expression levels of Foxp3, CD25, CTLA4, GITR, GATA3 and Tbet in MM patients and healthy donors showed no significant difference. Taken together, our study reveals the potential role of gamma delta regulatory T cells in inhibiting anti-tumor immune responses in MM patients. (C) 2016 Elsevier Inc. All rights reserved.