Immune response to genital chlamydial infection and influence of Chlamydia pneumoniae (TWAR) antibodies.

Chlamydial IgG antibodies at a titre of at least 32 were found to occur at approximately the same frequency (76-88%) in three groups of patients who had been treated for genital chlamydial infection. Twenty-four patients who had recovered from acute salpingitis, however, had a higher geometric mean titre (GMT; 176) than 59 pregnant women (GMT 44) or 61 patients with uncomplicated genital chlamydial infection (GMT 57). The chlamydial antibody titres thus seemed to reflect the severity of inflammatory involvement. Antibodies to the new species Chlamydia pneumoniae (previously known as Chlamydia TWAR), did not influence the frequency or titre of antibodies to Chlamydia trachomatis, arguing against the possibility of cross-reactivity or shared antigens. There was assumed to be no cross-immunity, since patients with Chlamydia trachomatis infection did not have a lower frequency of antibodies to Chlamydia pneumoniae.