The effect of Trichomonas vaginalis and the role of pH on cell culture monolayer viability.

In vitro, Trichomonas vaginalis produces contact-dependent cytotoxicity in which the monolayers are disrupted and monolayer cells die. In contrast, when cell-free filtrates of T. vaginalis culture supernatants are applied to a monolayer, detachment occurs but cell viability is maintained. Growth of T. vaginalis in culture results in a dramatic fall in pH. Both in systems where T. vaginalis grew in physical contact with McCoy cells and where they were physically separate, monolayers still disrupted; but the rate of death of McCoy cells significantly decreased when pH was rigidly controlled. This would indicate that cell death attributed to contact-dependent cytotoxicity is in part due to the drop in pH when T. vaginalis is grown in vitro.