This monofunctional CD4+ T cell phenotype does not have a widespread association with protection in animal and human models of infectious disease or cancer, with such emphasis often placed on polyfunctional CD4+ T cells51,54,55,56,57 and CD8+ T cells of both monofunctional58 and polyfunctional phenotypes59,60,61,62 during pre-clinical and clinical evaluation. The gene discussed is CD8A; the disease is infectious disease.