Chlamydia trachomatis as a possible agent of human autoimmune diseases.

A high percentage of patients (61.2%), suspected of having rheumatoid factor and autoimmune diseases, were infected with Chlamydia trachomatis (Ct). Patients with significantly high titres (greater than 256) against Ct (53.8%), also had a significant high level of antinuclear factor and anti DNA. Complement fractions, C3, C4 and the immunoglobulins, IgG, IgA and IgM, were also found in high levels. No cases of rheumatoid factor or autoimmune disease were diagnosed in a control group of patients. The results indicate that patients infected with Ct may develop rheumatic or connective-tissue diseases.