Intracellular expression of interleukin‐4 and interferon‐γ by a <i>Mycobacterium tuberculosis</i> antigen‐stimulated CD4⁺ CD57⁺ T‐cell subpopulation with memory phenotype in tuberculosis patients

Abstract

Summary In some chronic pathological conditions, antigen persistence activates and expands the CD4 + CD57 + T‐cell subset. The host immune response against tuberculosis infection is maintained through the continuous presence of antigen‐stimulated effector/memory helper T cells. To determine whether CD4 + CD57 + T cells were also expanded in human tuberculosis, we analysed (by flow cytometry) the phenotype of peripheral blood CD4 + T cells from 30 tuberculosis patients and 30 healthy controls. We observed a significant increase in the CD4 + CD57 + T‐cell subset in tuberculosis patients in comparison to healthy controls ( P &lt; 0·001). Most CD4 + CD57 + T cells exhibited a CD28 − CD45RO + CD62L − phenotype, which is associated with memory cells. In vitro , a higher number of antigen‐stimulated CD4 + CD57 + T cells produced intracellular interferon‐γ and interleukin‐4 compared with antigen‐stimulated CD4 + CD57 − T cells ( P &lt; 0·001). These findings suggest that the majority of CD4 + CD57 + T cells correspond to a phenotype of activated memory T cells.