The fact that rESAT-6-CFP10 fusion protein induced more CD4+CD25+Foxp3+ or CD4+CD25hiFoxP3+Treg cells at diagnosis of TB than at 2 months of treatment may suggest that the inflammatory response driven by Mtb is regulated by naturally-occurring Treg, which are capable of expansion in response to recall antigens. Here, CD4 is linked to tuberculosis.