CD4 and tuberculosis: The frequencies of CD244/2B4-expressing total CD4+ T cells were similar among active TB patients (n = 52), latent infection individuals (n = 12) and healthy controls (n = 38) (Fig. 2A), while the expression levels of CD244/2B4 on total peripheral CD4+ T cells were significantly higher in active TB patients than in latent infection individuals (p = 0.0025) and healthy controls (p = 0.0003) (Fig. 2B).