Depressed phagocytosis and oxidative burst in polymorphonuclear leukocytes from individuals with pulmonary tuberculosis with or without human immunodeficiency virus type 1 infection

Abstract

Phagocytosis and oxidative burst in whole-blood granulocytes were assessed by flow cytometry with Phagotest and Bursttest kits, respectively. Seventy individuals were included in this study: 15 healthy, normal donors, 18 human immunodeficiency virus (HIV) type 1 (HIV-1)-seropositive patients, 19 patients with pulmonary tuberculosis (TB), and 18 patients co-infected with Mycobacterium tuberculosis and HIV-1 (TB-HIV). Granulocyte phagocytosis was assessed by incubating whole blood with fluorescence-labelled Escherichia coli and measuring the proportion of granulocytes with ingested bacteria and the capacity (fluorescence intensity) of each cell to phagocytose E. coli. The percentage of granulocytes converting nonfluorescent dihydrorhodamine to fluorescent rhodamine 123 on production of reactive oxygen intermediates (ROIs) and the mean channel shift were assessed as a measure of oxidative burst. No differences in the proportion of granulocytes that were capable of phagocytosing or producing ROIs in response to E. coli were observed between any of the study groups, Phagocytosis was significantly enhanced in granulocytes from HIV-1-infected individuals. On the other hand, granulocytes from individuals infected with M. tuberculosis alone or in combination with HIV-1 had a significantly reduced capacity to phagocytose E. coli and to produce ROIs in response to E. coli as an agonist. These results provide evidence that granulocytes from individuals with pulmonary TB with or without concomitant infection with HIV-1 have an impaired ability to phagocytose and to undergo oxidative burst, possibly contributing to the enhanced susceptibility to opportunistic infections in these patients.