Thymosin α1 Enhances Human CD8⁺ T-Cell Activation and Reverses Exhaustion Markers In Vitro

The immune system can decline with age or chronic disease, often involving T-cell exhaustion, where T-cells lose their effector function. While Thymosin α1 (Tα1) is a known immunomodulatory thymic peptide, its precise effects on human CD8⁺ T-cell function, particularly in reversing exhaustion, remain underexplored. Understanding how Tα1 influences these critical immune cells could unlock new strategies for immunotherapy and combatting immune senescence.

Researchers cultured human CD8⁺ T-cells under four conditions: untreated, CD3/CD28 stimulation, Tα1 treatment, and combined CD3/CD28 + Tα1 treatment. Cell proliferation was quantified using CFSE-based flow cytometry. Surface expression of activation markers (CD69, CD25, HLA-DR) and exhaustion markers (PD-1, TIM-3, LAG-3) was analyzed via flow cytometry. Cytokine secretion (IL-2, IFN-γ, TNF-α, IL-10) was measured with a multiplex bead-based assay. T-cell exhaustion was experimentally induced by repeated CD3/CD28 stimulation prior to Tα1 intervention.

Tα1 alone led to a moderate increase in CD8⁺ T-cell proliferation and activation. However, the combination of Tα1 and CD3/CD28 stimulation significantly enhanced the proliferation index and surface expression of activation markers CD69, CD25, and HLA-DR compared to individual treatments. This synergistic effect points to Tα1's role in boosting T-cell responsiveness. Cytokine secretion, including IL-2, IFN-γ, TNF-α, and IL-10, was also elevated in the combination group, indicating enhanced effector function. In the induced exhaustion model, CD8⁺ T-cells exhibited overexpression of PD-1, TIM-3, and LAG-3.