RESUMO
To explore the nature and importance of mononuclear cells of different phenotypes in oral premalignant lesions and oral cancer, we studied biopsy specimens from 21 oral red and/or white lesions (6 hyperkeratosis, 3 mild dysplasia, 4 severe dysplasia and 8 squamous cell carcinoma), using monoclonal antibodies and avidin-biotin-peroxidase complex staining. Peripheral blood samples (PB) from 4 normal subjects and 5 reactive lymph nodes (LN) were used as controls for the technique. T11-positive cells were the predominant phenotype (74-78 por cento) in all cases examined. The T4/T8 ratio in severe dysplasia was significantly lower than that in mild dysplasia (p ó 0.05). These observations support the hypothesis of a role for cellular immune responses in oral premalignant lesions and oral cancer. The predominance of T cells may represent the local expression of immunity against antigens (viral or other). The decreased T4/T8 ratio observed in severe dysplasia may represent a transitory stage of local immunosuppression, which may be of critical importance for the progression into carcinoma. Phenotypic variations in mononuclear cell infiltrates in these conditions could be of diagnostic value