ATTACHMENT OF T-DENTICOLA STRAINS ATCC-33520, ATCC-35405, B11 AND NY541 TO A MORPHOLOGICALLY DISTINCT POPULATION OF RAT PALATAL EPITHELIAL-CELLS

In the present study an assay for the attachment of T. denticola to ep ithelial cells is described. An indirect immunohistochemical staining method, using two native polyclonal antisera, revealed dark-brown colo ured spirochetes attached to rat palatal epithelial cell (RPE) monolay ers. In addition, two morphologically distinct populations of RPE cell s could be distinguished in the monolayers when using phase contrast m icroscopy. One minor population consisted of isolated rounded RPE cell s that were lying on top of a confluent monolayer of flattened RPE cel ls. The rounded RPE cells were more receptive for the attachment of T denticola than the flattened cells. The rounded RPE cells were evenly distributed over the monolayer, but the attachment of spirochetes to t he rounded cells was greater at the edge than in the centre of the mon olayers. The percentage of rounded RPE cells with attached spirochetes depended on the incubation time (optimum 6 h), temperature (optimum 3 7-degrees-C) and pH (optimum 7.0). It is speculated that the attachmen t of T denticola is a physical/chemical process of yet unknown nature and that differences in the number of microvilli and/or the amount of available receptors, between the two morphologically distinct cell typ es, accounts for the differences in the numbers of attached spirochete s.