Altered dynamics of T cell subsets in peripheral blood impacts disease progression in newly diagnosed multiple...

T cells are essential for tumor immunosurveillance and disease regulation in Multiple Myeloma (MM), but their role in disease pathogenesis is not well understood. To investigate this, we analyzed T cell subsets for activation status, relative distribution of naïve and memory T cell populations, regulatory T cells (Tregs), and circulating follicular helper T cells (cT_FH) in the peripheral blood of 40 newly diagnosed MM (NDMM) patients. We also assessed inhibitory receptor expression CD160, ICOS/CD278, CD152/CTLA-4, and PD-1/CD279 on T cells in peripheral blood. Our results showed reduced T cell numbers, an imbalance between naïve and effector CD4⁺ T cells, and decreased memory Tregs in newly diagnosed MM patients compared to healthy controls. Furthermore, plasma cells in the bone marrow correlated with percentage of activated cT_FH cells and inhibitory receptor expressing T cells in peripheral blood indicating that disrupted T cell homeostasis and immune-mediated processes may drive disease progression in NDMM.