CD4 and pulmonary tuberculosis: A similar phenomenon was observed in human PBMCs from pulmonary TB patients and healthy donors; when CD84− CD4+, CD84− CD8+, CD84+ CD4+, and CD84+ CD8+ T cells were sorted and analyzed by flow cytometry, we found significantly higher expression of CD69 on CD84− CD4+ and CD84− CD8+ T cells than on CD84+ CD4+ and CD84+ CD8+ T cells (Fig. 3c).