Immunohistochemical localization of fibronectin-like protein on the cell surface of the oral flagelatte Trichomonas tenax.
A protein immunologically related to fibronectin was demonstrated on the oral flagellate Trichomonas tenax. Two strains of T. tenax were used, the first freshly taken from ulcerative gingivitis and the second maintained in culture for 2 years. Initial investigations were made by established immunofluorescence staining procedures. Cells of the protozoa gave a positive fluorescence with anti-fibronectin anti-serum, while the controls were negative. Subsequently, indirect immunostaining procedures for electron microscopy were performed using the peroxidase procedure. Peroxidase deposits were detected on the outer layer of the cell membrane. Particularly intense labelling was localized in the contact areas between bacteria and protozoa, and sometimes within the marginal lamina of the undulating membrane. This fibronectin-like protein could potentially play an important role in the adhesion of Trichomonas tenax to gingival cells, connective tissue and in the phagocytosis of bacteria. The attachment of protozoa to gingival substrates could be the first step in the breakdown of periodontal tissues.