Increased production of hydrogen peroxide and expression of CD11b/CD18 on alveolar macrophages in patients with active pulmonary tuberculosis.
METHODS
Alveolar macrophages (AM) are important in host defense against Mycobacterium tuberculosis (TB). beta 2-integrins, especially CD11a/CD18 and CD11b/CD18, are implicated in leukocyte migration, antigen presentation, phagocytosis, and production of reactive oxygen species.


OBJECTIVE
To explore the functional relevance of beta 2-integrin expression to intracellular H2O2 capacity of AM in TB patients.


METHODS
In a prospective study, AM retrieved from 18 active pulmonary TB patients and 18 normal subjects were assessed for beta 2-integrin expression and intracellular H2O2 metabolism capacity by loading with anti-CD11a/CD18, anti-CD11b/CD18 monoclonal antibodies and 2',7' dichlorofluorescein diacetate (DCFH-DA) respectively, and analyzed by flow cytometry. AM from 8 normal subjects were stimulated with tumor necrosis factor-alpha (TNF-alpha, 10(5) units/ml) to examine the relationship between H2O2 production and CD11b/CD18 expression.


RESULTS
The magnitude of DCFH oxidation and CD11b/CD18 expression of AM was higher in TB patients than in normal subjects. The CD11b/CD18 expression was related to the magnitude of DCFH oxidation, but not to lymphocyte numbers or subpopulations (CD4, CD8, CD25). Stimulation of AM with TNF-alpha increased H2O2 production and CD11b/CD18 expression. Pretreatment with CD11b/CD18 monoclonal antibodies inhibited TNF-alpha-induced H2O2.


CONCLUSIONS
AM in TB patients possessed a higher capacity of oxidant metabolism. The increased CD11b/CD18 expression may be related to the increased respiratory burst response in AM against mycobacterial invasion.
Kuo
H P
HP
Department of Thoracic Medicine, Chang Gung Memorial Hospital, Taipei, Taiwan.
Ho
T C
TC
Wang
C H
CH
Yu
C T
CT
Lin
H C
HC
D000328:Adult; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D018845:CD11 Antigens / Q000378:metabolism*; D018821:CD18 Antigens / Q000378:metabolism*; D018929:Cell Culture Techniques; D002469:Cell Separation; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014397:Tuberculosis, Pulmonary / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
D018845:CD11 Antigens; D018821:CD18 Antigens; D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide