Objective To elucidate the functional status of dendritic cells (DC) in the tissue of oral squamous cell carcinoma by analyzing characteristic phenotype of them.Methods 34 specimens from oral squamous cell carcinoma cases primarily treated with surgery were selected as test group.In addition, 30 specimens of normal mucosa from oral mucocele cases were used as con- trol. Distribution of DC expressing CD1a+, HLA-DR+and CD83+in tumortissue and normal mucous membrane was observed by immunohistochemistry. The number of DC expressingthe antigens, which represented the density of DC infiltrating intotissue, was counted by microscope. The density of DC and the rate of DC expressingHLA-DR in oral carcinoma group and controlwere statis- tically compared.Results There was no CD83+DC in all cases, but CD1a+DC was found in all samples. The density of CD1a+DC in tumortissue was significantly lowerthan that in normal mucous membrane (P
