G1 cyclins in oral epithelial dysplasia.

The G1 cyclins, D1, D3 and E, were investigated in 38 lesions of oral epithelial dysplasia from the floor of the mouth or the lateral border of the tongue. Their immunohistochemical expression was observed and compared with that of Ki-67 and with the degree of dysplasia assessed by the semiobjective technique of Smith & Pindborg. Antibody labelled cells were quantified and expressed as a percentage (LI%) of the total nucleated cell population and per mm basement membrane length (LI/mm). The labelling indices of all of the antibodies were high and quantitatively similar. There were no significant correlations with the degree of dysplasia assessed by the atypia scores. There was a correlation between labelling indices for the various antibodies expressed as LI/mm but little correlation between the indices expressed as LI%. The distribution of the D cyclins was similar to that of Ki-67 with relatively few of the basal cells demonstrating immunoreactivity. The reasons for this are discussed in the paper. Some cross-reactivity was observed with the cyclin antibodies. We conclude that the antibodies against the cyclins used in the present study are not a useful adjunct in the study of the cell kinetics of oral epithelial dysplasia.