IgG subclass specific antibody response to periodontopathic organisms in HIV-positive patients

Background: We previously reported an increased rate of progression of periodontal disease over an 18-month period in human immunodeficiency virus (HIV)-positive subjects compared to controls. The mechanism for disease progression and rapid tissue loss was unknown. Data on the microbiological studies failed to show any significant difference in the microbial characteristics of the periodontal lesions in HIV-positive patients compared to HIV-negative controls. Immunological analysis had identified neutrophils as an important component of the host defense against periodontal infection, especially against rapid tissue loss. Serum IgG reactivities to periodontal pathogens in HIV-positive patients with periodontitis were reduced. Other data provided circumstantial evidence to suggest that IgG subclass (IgG(2)) specific antibody might assist bacterial clearing in periodontal infection. The aim of the current study was to examine the specific IgG subclass antibody response to a panel of periodontopathic organisms: Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn), Campylobacter rectus (Cr), and Bacteroides forsythus (Bf) in HIV-positive patients compared to HIV-negative controls. Methods: Sera from 120 HIV-positive patients (40 periodontitis, 69 gingivitis, and 11 no oral diseases) were tested for IgG subclass specific antibody response to the above listed 6 organisms using enzyme-linked immunosorbent assay. Data were compared with those obtained from 40 HIV-negative control subjects (35 periodontitis, 2 gingivitis, and 3 no oral diseases). Results: In the HIV-positive group, a consistently high response rate was found in IgG(1)to all the bacteria tested. In addition, high levels of IgG(3) and IgG(4) to Pg and IgG(1) and IgG(2) to Pi were also present. However, no significant difference was detected among the periodontitis, gingivitis, and no oral disease subgroups. When the periodontitis patients from the HIV-positive group were compared to the HIV-negative group, no difference in the antibody levels and response rates was noted. Conclusion: We conclude that in HIV-positive patients, the specific IgG subclass antibody response to periodontopathic organisms was similar to that of HIV-negative subjects.