Evidence of chronic Chlamydia pneumoniae infection in patients with Behçet's disease

Behçet's disease is a chronic vasculitis of unknown aetiology. Particular viral and bacterial pathogens have long been suspected of playing a role in the pathogenesis of the disease. Chlamydia pneumoniae is an intracellular bacterium capable of causing chronic infections. Some reports have suggested that the microorganism might be involved in the pathogenesis of vasculitis. The purpose of the present study was to investigate a possible correlation between C. pneumoniae infection and Behçet's disease. For this purpose, 90 consecutive patients with Behçet's disease and 50 healthy controls were enrolled. Immunoglobulin A (IgA) and IgG antibodies to C. pneumoniae were determined by 2 different techniques, namely indirect fluorescent antibody assay (IFA) and enzyme linked immunosorbent assay (ELISA). IgA antibodies to C. pneumoniae were detected in 17 (18.9%) patients with Behçet's disease and in 1 (2%) healthy control by IFA. By ELISA 27 patients (30.0%) and 6 controls (12.0%) had C. pneumoniae IgA. A significant difference was observed for IgA seropositivity between the 2 groups. Although IgG seropositivity between the 2 groups did not differ significantly, the number of individuals with IgG titres of > or = 1:1000 was significantly higher in the patient group (43.1%) compared with the control group (13.9%). These finding provide serological evidence of chronic C. pneumoniae infection in association with Behçet's disease.