Lymphocyte subpopulations in active tuberculosis: association with disease severity and the QFT-GIT assay.

Cell-mediated immune response plays an essential role in the pathogenesis of tuberculosis (TB). We retrospectively evaluated lymphocyte subpopulations in 177 active TB patients compared to 93 healthy controls, finding a relevant decrease in total lymphocytes and CD8+ cells. Conversely, activated human leukocyte antigen (HLA-DR+) and CD4+CD57+ cells were higher in the TB group. B-1a (CD5+CD19+) lymphocytes were reduced in TB subjects, particularly those with extended and cavitary pulmonary forms, suggesting increased compartmentalisation at the infection site. QuantiFERON-TB Gold In-Tube positive results were associated with higher HLA-DR+CD4+ and CD4+CD57+ cells, while interferon-gamma response and total lymphocyte levels were lower in advanced pulmonary TB cases.