Immunohistologic study of mononuclear cell infiltrates in oral squamous cell carcinomas

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Abstract
Intensity of mononuclear cell infiltrates in 50 oral cancer tissues was evaluated by immunohistochemical stainings. The intensity of the infiltrates was graded into four degrees from marked (+ + +) to absent (‐); and the degree of each infiltrated lymphocyte subpopulation including Leu‐3a3b/Leu‐2a ratio was matched against clinical and histopathologic features. The vast majority of the infiltrated lymphocytes had antigens which were reactive with anti‐T cell antibodies. In T cell subsets, Leu‐3a3b+ cells infiltrated clearly (grade ++ or +++) in 44 cases, and infiltration greater than grade + + of Leu‐2a+ cells was found in nearly half of the cases (26 of 50). In contrast, B cells (Leu‐14+ cells) were obviously detectable in only a few cases, and moderate or marked infiltration of the natural killer (NK) population (Leu‐11b+ cells) was not observed. Regarding correlation of T cell infiltrates with clinicopathologic features of the tumors, the degrees of Leu‐4+ cell and Leu‐2a+ cell infiltration became weak with advancing T stage. Leu‐2a+ cells also infiltrated weakly into diffusely invading tumors. Out of 28 cases with no metastasis, 22 cases (78.6%) showed grade ++ ∼ + + + of Leu‐2a+ cells, and only 4 (18.2%) of 22 cases with lymph node metastasis were clearly positive for Leu‐2a+ cells (p < 0.001). However, Leu‐3a3b+ cell infiltration was only slightly related to T stage, metastasis, and to mode of invasion. Therefore, the Leu‐3a3b/Leu‐2a ratio increased significantly in advanced (T3 + T4) tumors, metastasized cases, or diffuse invasion type.