The regulation by iron of the synthesis of adhesins and cytoadherence levels in the protozoan Trichomonas vaginalis

Levels of adherence of Trichomonas vaginalis to epithelial cells was found to be modulated by iron. Cytoadherence values were greater than or equal to twofold higher for trichomonads grown in a complex cultivation medium supplemented with iron. This increase in adherence levels was specifically mediated by iron; parasites cultured in a low-iron medium in the presence of salts other than iron were unresponsive to changes in adherence levels. Expression of the higher adherence property, by parasites grown first in low-iron medium followed by supplementation with iron, was a function of time, and the extent of cytoadherence was proportional to the concentration of iron added to the medium. Lactoferrin, an important iron source for trichomonads at the site of infection, elevated adherence of the parasite to epithelial cells, demonstrating the likely in vivo modulation of adherence by iron.