Trichomonas vaginalis: in vitro phagocytosis of lactobacilli, vaginal epithelial cells, leukocytes, and erythrocytes.

This paper explores the interaction of two strains of Trichomonas vaginalis, of high and low virulence, with the cell types present in the microenvironment of the parasite during human infections. With the use of transmission and scanning electron microscopy the sequence of internalization by T. vaginalis of Döderlein's lactobacilli, and of vaginal epithelial cells, leukocytes, and erythrocytes was documented. Furthermore, the degradation of ingested material by colocalization of acid phosphatase activity in phagocytic vacuoles was demonstrated. Phagocytosis of all cell types analyzed was found in both strains studied, although the highly virulent strain internalized target cells more rapidly than the less virulent one. Ultrastructural evidence indicated that phagocytosis takes place through two distinct mechanisms, only one involving the formation of a phagocytic stoma, characteristic of professional phagocytes. T. vaginalis phagocytosis may be both an efficient means of obtaining nutrients for the parasite and a significant factor in the pathogenesis of trichomonal infections of the human genitourinary tract.