Changes in T-lymphocyte subsets in lungs and spleens of mice with slowly progressive primary Mycobacterium tuberculosis infection: Involvement of unconventional T-cell subsets

Our previous study showed that the cell-activation responses and cytokine-s ecretion patterns were different in lungs and spleens of mice with slowly p rogressive primary Mycobacterium tuberculosis infection. The aim of the pre sent study was to characterize the T-cell subsets in lungs and spleens of m ice with a similar infection. The percentages of T-cell subsets were determ ined by flow cytometry and the absolute numbers were calculated. Spleens of infected mice showed a threefold expansion of CD4(+) cells but no change i n CD8(+) cells, whereas lungs had a threefold increase of both subsets. A s ignificant expansion of CD4(-)CD8(-)alpha beta(+) [double negative (DN)alph a beta(+)] subsets was observed in the lungs of infected mice compared with uninfected mice. This was not the case in the spleens of infected mice. In infected mice the CD4(-)CD8(-) (DN) population preferentially expressed al pha beta-T-cell receptors (TCR) in the lungs but gamma delta-TCR in the spl eens. The percentages of many T-cell subsets were significantly higher in t he lungs than in the spleens of both uninfected and infected mice. However, the percentages of CD4(+) and CD4(-)CD8(+)TCR(-) subsets in the lungs were significantly lower than in the spleens of infected mice. We also observed some previously unreported T-cell subsets: double positive-TCR- (DPTCR-), DP alpha beta(+) and DP gamma delta(+). So far their functions are unknown.