CHLAMYDIA-PNEUMONIAE ANTIBODIES IN CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

Background. The significance of persistent or recurrent respiratory in fections in adult life for the development of chronic obstructive pulm onary disease (COPD) is still to a large extent unknown, A few clinica l and experimental animal studies suggest that peripheral airways dise ases may be due to the cumulative effects of recurrent respiratory inf ections over an extended period. Methods. C. pneumoniae-specific IgG a nd IgA antibody levels were determined in two elderly groups of male p atients with COPD and in control subjects without the disease. The fir st group (N = 36) consisted of patients who were hospitalized due to a n acute exacerbation of COPD. The second group of patients (N = 54) an d the controls (N = 321) were participants in a community survey on re spiratory diseases in the elderly, The criteria for seropositivity wer e defined as an IgG titre of greater than or equal to 32 and an IgA ti tre of greater than or equal to 16. Results. 89% of the hospitalized p atients (group I) acid 66% of the non-hospitalized patients (group II) were IgA-seropositive as compared to 55% of the controls. Derived fro m the logistic regression analysis, the odds ratio (OR) was 7.4 (95% C I : 2.1-25.7) between group I and the controls and 1.5 (0.7-2.9) betwe en group II and the controls. Furthermore, the difference in the age-a djusted geometric mean titres (GMT) of IgA antibodies between the grou p I and the controls was significant (53.0 for the patients versus 19. 1 for the controls). On the contrary, no significant differences betwe en the patients and the controls were found either in the proportion o f IgG-seropositive or in the GMT of IgG antibodies. Two of the 29 pati ents with an exacerbation of COPD, for whom paired sera were available , showed an antibody response suggesting a current acute or reactivate d chlamydial infection. Conclusions. The results showed that C. pneumo niae IgA antibodies are found more frequently and in higher concentrat ions in COPD patients than in disease-free controls. The finding may i ndicate a chronic C. pneumoniae infection in these patients. The assoc iation persisted after controlling for the potential confounding effec t of smoking.