Memory T cells are hallmark of acquired immunological responses. The relationship of mycobacterial antigen-specific CD4⁺ memory T cell subsets with pulmonary tuberculosis was investigated.

The mycobacterial antigen-specific CD4⁺ T cells were detected based on CD154 expression and phenotypes of memory T cell were analyzed by surface staining of CD45RA and CCR7 and flow cytometrical analysis in patients with pulmonary tuberculosis and in tuberculin-positive healthy controls. The association of antigen-specific CD4⁺ memory T cell subsets with disease severity and anti-TB treatment was analyzed in patients with pulmonary tuberculosis.

Patients with pulmonary tuberculosis had significantly lower frequencies of antigen-specific central memory T cells (T_CM) (p=0.019) and higher frequencies of effector memory T cells (T_EM) (p=0.022) compared with tuberculin-positive healthy controls without tuberculosis. Patients with smear/culture positive results showed lower population frequencies of T_CM and significantly higher frequencies of T_EM (p=0.015) than those with smear/culture negative results. Treatment of TB patients with standard antibiotic regimens for more than one month led to significantly increased frequencies of T_CM (p=0.031).

The frequencies of mycobacterial antigen-specific T_CM and T_EM are associated with disease severity of pulmonary tuberculosis and T_CM are associated with short-term effects of anti-TB chemotherapy.