Cytokine concentrations in seminal plasma from subfertile men are not indicative of the presence of Ureaplasma urealyticum or Mycoplasma hominis in the lower genital tract.

The inflammatory response to the presence of Ureaplasma urealyticum or Mycoplasma hominis in the lower genital tract of subfertile men without any signs or symptoms of infection was investigated by measuring the concentrations of interleukin (IL)-6, IL-8, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in seminal plasma. Semen samples were collected from 30 culture-positive subfertile males and 23 culture-negative subfertile males. Enzyme-linked immunosorbent assays showed that IL-8 was present in relatively high concentrations (0.12-4.8 ng/ml) in all semen samples investigated. In contrast, the other cytokines were only detectable in 72% (IFN-gamma), 44% (IL-6) and 19% (TNF-gamma) of the samples and were present in relatively low concentrations (1-410 pg/ml). Seminal plasma cytokine concentrations were similar in samples from culture-positive and culture-negative males. These data strongly indicate that the presence of U. urealyticum or M. hominis in the lower genital tract of subfertile males reflects a silent colonisation rather than infection.