Differential expression of immune activation markers in T cells from patients with multiple myeloma

Multiple myeloma (MM) is the second most common hematological malignancy, characterized by the abnormal proliferation of malignant plasma cells leading to the classic CRAB symptoms. Despite advances in treatment, MM remains incurable. Alterations in the tumor immune microenvironment (TIME) contribute to therapy resistance. However, the activation status of T cells, key regulators of immune responses, is still not fully understood in MM.

To further investigate immune alterations in the tumor microenvironment, bone marrow samples were collected from 18 newly diagnosed MM patients and 12 age- and sex-matched healthy controls. Multiparameter flow cytometry was used to analyze T cell subsets and their activation markers.

We observed a significant increase in the proportions of CD4⁺ central memory T cells (Tcm) and CD8⁺ Tcm in MM patients, while CD4⁺ effector memory T cells (Tem) and CD4⁺ TEMRA cells were significantly decreased. In terms of activation markers, MM patients showed increased frequencies of CD95⁺ CD4^- TEMRA, CD95⁺ CD8^- Tn, CD278⁺ CD4^- TEMRA, and HLA-DR⁺ CD4^- Tem subsets compared to healthy controls. In contrast, CD95⁺ CD8⁺ Tcm, CD278⁺ CD8⁺ Tn, CD278⁺ CD8⁺ Tcm, and HLA-DR⁺ CD8⁺ Tcm subsets were significantly reduced.

These findings reveal differences in the composition and activation profiles of T cell subsets in the bone marrow of MM patients. While they provide insights into the immune landscape of MM, further studies are needed to clarify their functional significance and potential implications for therapeutic strategies.