Lung fluid immunoglobulin from HIV-infected subjects has impaired opsonic function against pneumococci.
BACKGROUND
The incidence of pneumococcal pneumonia is greatly increased among human immunodeficiency virus (HIV)-infected subjects, compared with among non-HIV-infected subjects. Lung fluid levels of immunoglobulin G (IgG) specific for pneumococcal capsular polysaccharide are not reduced in HIV-infected subjects; therefore, we examined immunoglobulin subtypes and compared lung fluid IgG opsonic function in HIV-infected subjects with that in healthy subjects.


METHODS
Bronchoalveolar lavage (BAL) fluid and serum samples were collected from 23 HIV-infected and 26 uninfected subjects. None of the subjects were receiving highly active antiretroviral therapy, and none had received pneumococcal vaccination. Pneumococcal capsule-specific IgG levels in serum and BAL fluid were measured by enzyme-linked immunosorbent assay, and IgG was concentrated from 40 mL of BAL fluid. Opsonization and opsonophagocytosis of pneumococci with serum, BAL fluid, and BAL IgG were compared between HIV-infected subjects and healthy subjects.


RESULTS
The effect of type 1 pneumococcal capsular polysaccharide-specific IgG in opsonizing of pneumococci was significantly less using both serum and BAL IgG from HIV-infected subjects, compared with serum and BAL IgG from healthy subjects (mean level, 8.9 fluorescence units [95% confidence interval, 8.1-9.7 fluorescence units] vs. 12.1 fluorescence units [95% confidence interval, 9.7-15.2 fluorescence units]; P=.002 for lung BAL IgG). The opsonophagocytosis of pneumococci observed using BAL IgG from HIV-infected subjects was significantly less than that observed using BAL IgG from healthy subjects (37 fluorescence units per ng of IgG [95% confidence interval, 25-53 fluorescence units per ng of IgG] vs. 127 fluorescence units per ng of IgG [95% confidence interval, 109-145 fluorescence units per ng of IgG]; P<.001).


CONCLUSIONS
HIV infection is associated with decreased antipneumococcal opsonic function in BAL fluid and serum.
Eagan
Roger
R
Division of Pulmonary, Allergy, Critical Care, and Occupational Medicine, Indiana University Medical Center, Indianapolis, IN, USA.
Twigg
Homer L
HL
French
Neil
N
Musaya
Janelisa
J
Day
Richard B
RB
Zijlstra
Eduard E
EE
Tolmie
Helen
H
Wyler
David
D
Molyneux
Malcolm E
ME
Gordon
Stephen B
SB
D000328:Adult; D016667:Bacterial Capsules / Q000276:immunology*; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology*; D016022:Case-Control Studies; D005260:Female; D015658:HIV Infections / Q000276:immunology* / Q000382:microbiology; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis* / Q000276:immunology; D008297:Male; D009895:Opsonin Proteins / Q000032:analysis / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology; D013296:Streptococcus pneumoniae / Q000276:immunology*
D007074:Immunoglobulin G; D009895:Opsonin Proteins