CD4 and tuberculosis: The objective of this study was to (1) investigate whether any association exists between CD153-expressing Mtb-specific CD4 T cells and bacterial load in sputum of those with active TB, (2) define the effect of HIV coinfection on this cell subset, and (3) assess the impact of successful antitubercular therapy (ATT) on CD153 expression by CD4 T cells responding to Mtb.