Patients with Multiple Myeloma Have Increased Co-Expression of HLA-E and HLA-DR Molecules on T-Lymphocytes and Monocytes in Peripheral Blood

Background/Objectives: Multiple myeloma (MM) is characterized by complex interactions between tumor plasma cells and the tumor microenvironment, in which immune escape mechanisms play a key role. Non-classical major histocompatibility complex (MHC) molecules HLA-E and HLA-G are receptors capable of suppressing the activity of NK cells and T lymphocytes. However, their expression on immune cells in oncology, particularly in MM, remains poorly understood. Methods: Peripheral blood mononuclear cells from patients with MM and healthy controls were used as study material. HLA-E and HLA-G expression on T lymphocytes and monocytes was analyzed using flow cytometry. Results: MM was shown to be associated with increased expression of non-classical molecule HLA-E by T lymphocytes and monocytes, as well as an increased proportion of cells with phenotype HLA-E+HLA-DR+ among cells. Conclusions: Our study demonstrates that non-classical HLA-E molecule are actively expressed on immune cells in multiple myeloma, which may serve as a mechanism for tumor immune evasion. These data support further exploration of HLA-E as potential target for MM immunotherapy.