RESUMEN
Trichomoniasis may be asymptomatic or symptomatic in both sexes. The outcome of infection depends on the virulence factors of T vaginalis, but these factors remain unclear. Genetic variability of the isolates and the host's immune response are likely to be key factors in that respect. Symptomatic and asymptomatic males infected with T. vaginalis were compared regarding the differences in antibody subclasses response in the urethral samples. In symptomatic cases there was a significant elevation in IgM, IgG1 and IgG2b levels in urethral samples, and a little, non-significant rise in IgG2a levels. However, there were no statistically significant differences between levels of IgA, IgG3 and IgG4. The results showed that specific IgG1 and IgM and to a lesser extent IgG2 may be involved in established symptomatic trichomoniasis in men, compared to asymptomatic ones