Natural killer cell subpopulations in putative resistant individuals and patients with active Mycobacterium tuberculosis infection.

Herein, we intended to perform flow-cytometric analyses of peripheral blood NK-cell subsets in patients with active tuberculosis (TB) and those putative resistant subjects displaying positive tuberculin skin test (TST+) and compared with TST- healthy controls. Our findings demonstrated distinct phenotypic features in TST+ as compared with TB. While lower values of NK-cells with increased frequency of CD3-CD16+ CD56- and CD3-CD16-CD56+ subsets besides lower frequency of CD3-CD16+ CD56+ NK-cells was observed in TST+, unaltered levels of NK-cells with increased levels of CD3-CD16+ CD56- NK-cells with lower frequency of CD3-CD16+ CD56+ NK-cells was found in TB. Additional analysis highlighted a shift towards increased levels of CD3-CD16-/+CD56bright NK-cells as the hallmark of TST+, whereas unaltered frequency was observed in TB. Increased levels of CD3+CD56+ cells were observed in both TST+ and TB. Further focusing on the monocyte/NK-cell network, we have reported that enhanced frequency of CD14+ CD16+ monocytes particularly observed in TST+. Outstanding were the distinct correlation profiles observed between CD3-CD16-CD56+ NK-cells and CD3+ CD56+ cells CD14+ CD16+ monocytes for TST+ and TB. These data suggested that high levels of CD3-CD16-CD56+ NK-cells aside CD14+ CD16+ monocytes as well as non-concurrent increment of CD3+ CD56+ cells, may be involved in protective mechanisms in putative tuberculosis-resistant individuals. On the other hand, the basal levels of macrophage-like monocytes despite its positive correlation with increased levels of CD3+ CD56+ cells may count for the lack of the protective immunity in patients with active tuberculosis. Further studies focusing on the cytokine profiling of peripheral blood innate immunity cells before and after chemotherapeutic treatment are currently under evaluation.