MAGE-A3-specific memory T cell induction from healthy donors: a functional in vitro evaluation

Aim: To determine whether PepTivator® melanoma-associated antigen-A3 (MAGE-A3) primes early T-cell activation and memory skewing in human peripheral blood mononuclear cells (PBMCs). Methods: PBMCs from 10 donors were stimulated with MAGE-A3 (manufacturer-recommended dose), negative control (NC), or CD3/CD28 and CytoStim™ (PC: positive control). Activation [CD69, CD25, HLA-DR (human leukocyte antigen-DR isotype)], proliferation, cytokines [24 h; GM-CSF (granulocyte-macrophage colony-stimulating factor), IFN-γ (interferon-gamma), IL-2 (interleukin-2), TNF-α (tumor necrosis factor-alpha)], and memory phenotypes (CD45RO/CD27 at days 0/7/14) were quantified by flow cytometry and MACSPlex. Paired statistics used repeated-measures models with Šidák correction; cytokines were analyzed on log10 scale. Results: MAGE-A3 significantly increased early activation (CD69 ↑, CD25 ↑) and modestly increased proliferation, with selective IL-2/TNF-α rise and minimal IFN-γ and modest HLA-DR. Across two weeks, 6/10 donors showed increased central memory T cell (TCM)/effector memory T cell (TEM) with a corresponding decline in naïve cells relative to NC. Variability across donors was evident. Conclusions: MAGE-A3 primes partial activation and memory skewing of human T cells in vitro, suggesting utility as a component antigen that likely benefits from professional antigen-presenting cell (APC) presentation and/or costimulation. We discuss limitations (single dose, in vitro context, donor variability) and implications for future dose-response, HLA-stratified, and APC-supported studies.