Natural T, γδ, and NK cells in mycobacterial, Salmonella, and human immunodeficiency virus infections

NK cells, gamma delta T cell antigen receptor chain-positive cells, and CD3(+)CD16/56(+) (natural T [NT]) cells are involved in innate immunity and immunoregulation; however, their role in clinical infection is not well defined. Cytofluorometric analysis was used to examine peripheral blood from bacteremic, nonbacteremic, and healthy human immunodeficiency virus (HIV)-positive and -negative persons in Malawi, Africa. Mycobacteremia was associated with a higher proportion of CD3(+)CD8(-) gamma delta cells (median, 16.6% a vs. 0.7% for all other cells; P < .001), and Salmonella bacteremia was associated with a higher proportion of NT cells (4.3% vs. 2.2%; P = .002). HIV plasma RNA levels were weakly positively correlated with NT cells (r(s) = .39; P = .002), NK cells (r(s) = .38; P = .003), and gamma delta cells (r(s) = .43; P < .001). Compared with patients who survived, patients who died had a higher percentage of NT cells (3.7% vs. 1.9%; P = .017) and a higher percentage of NT cells that spontaneously produced interferon-gamma (2.4% vs. 1.2%; P = .035). The data support the clinical relevance of gamma delta and NT cells in mycobacterial, Salmonella, and HIV infections and of NT cells in mortality.