Chlamydia trachomatis antibodies in serum and ejaculate of male patients without acute urethritis.

In a prospective study, the prevalence of specific antibodies against Chlamydia trachomatis in serum and seminal plasma evaluated by a genus specific immunofluorescence test in 101 men without acute urethritis was investigated. The results were compared to the clinical diagnosis, cell culture of urethral swabs, demonstration of DNA particles by Polymerase Chain Reaction (PCR) in the ejaculate and signs of genital inflammation by counting peroxidase-positive leukocytes and elastase level in semen. The objective was to evaluate the significance of chlamydial antibodies in genital infection. Serum specific IgG and IgA antibodies were found in 26% and 15%, respectively; seminal IgG and IgA antibodies were present in 6% and 7%, respectively. Serum specific antibodies were not associated with the clinical diagnosis of infection nor with C. trachomatis cell culture, PCR findings, peroxidase positive leukocytes or PMN-elastase level. It is concluded that serum antibodies are not useful in detecting a chlamydial infection. Seminal plasma antibodies were not correlated with the clinical diagnosis of infection, positive cell culture, PMN-elastase levels and leukocytes in semen. However, a significant correlation was found for positive PCR in the ejaculate (p < 0.001 for IgG, p < 0.05 for IgA, p < 0.001 when combined). Though seminal antibodies may be more useful in detecting ascended or occult chlamydial infection, their significance remains unclear, their absence does not exclude chlamydial infection. In particular, the biological significance of locally derived IgA needs further evaluation.