Intracellular cytokine production of IFN-γ and IL-2 upon PMA/lonomycin or T cell receptor (TCR) cross-linking stimulation was reduced in CD4+ and CD8+ T cells of breast cancer patients (9/19) compared to healthy donors’ (19/19) PBMCs, further indicating impaired function of these cells. Here, IFNG is linked to breast carcinoma.