ABSTRACT
Background: Tuberculosis (TB) can have manifestations closely mimicking autoimmune diseases. The prevalence of autoantibodies in TB varies among different populations. Objectives: To study the prevalence of anti-neutrophilic cytoplasmic antibodies (ANCA) and antinuclear antibodies (ANA) in pulmonary tuberculosis (PTB). Methods: This was a cross-sectional, observational study. Subjects with microbiologically confirmed PTB, either via smear or culture positivity on sputum or bronchoalveolar lavage (BAL) fluid, or positive rapid diagnostic tests were included. ANCA against proteinase-3 (PR3), myeloperoxidase (MPO), lactoferrin, and elastase were tested using an enzyme-linked immunosorbent assay (ELISA). ANA was detected using indirect immunofluorescence (IIF). Results: Eighty-nine subjects with a median [interquartile range (IQR)] age of 28 (20–46) years, 67.4% males, were recruited. Eighty-one subjects had microbiological confirmation on sputum examination, and eight required examination of BAL fluid. Sera were drawn from 62 treatment-naïve subjects, the rest (27) were on antitubercular therapy (ATT). Eighty-six (96.6%) subjects tested positive for anti-elastase antibody, seven of which were also positive for anti-PR3. None were positive for anti-MPO and anti-lactoferrin. Six (6.7%) subjects tested positive for ANA. None of the subjects had features of underlying connective tissue disease or vasculitis. Conclusion: PTB patients showed a high prevalence of anti-elastase and a low prevalence of ANA and anti-PR3 antibodies. ANCA positivity should be interpreted with caution in TB endemic areas. The role of anti-elastase antibodies in differentiating TB from ANCA-associated vasculitis (AAV) needs further research.
ABSTRACT
PURPOSE: Besides well-defined environmental causes, accumulating evidence suggests that respiratory tract infections play an important role in the pathogenesis of asthma. Among these Chlamydia pneumoniae infection has been discussed as possibly inducing the development of asthma. METHODS: This study was designed to investigate the presence of anti chlamydial IgG, IgA, and IgM antibodies by ELISA in serum samples of 60 adults with a clinical history of asthma and 100 healthy age and sex matched controls. All the samples positive for Chlamydial genus specific IgG antibodies were then subjected to Chlamydia pneumoniae species specific IgG antibody ELISA. RESULTS: The IgG anti chlamydial antibody-positivity rate in the patients with bronchial asthma (80%) was significantly higher in all age groups than that in the healthy age and sex matched controls (59%). No significant association was observed for IgA and IgM anti chlamydial antibodies. C. pneumoniae species specific IgG antibody seroprevalence was also found to be significantly higher in all age groups in comparison to controls (61.66% vs 38%). CONCLUSIONS: Serological evidence of chronic infection with C. pneumoniae was more frequent in patients with asthma compared with control subjects. Our results support the correlation of bronchial asthma and chronic infection with C. pneumoniae in Indian population.