Immunohistologic detection of lymphocyte subpopulations infiltrating in human oral cancer with special reference to its clinical significance

Cancer tissues from 30 patients with squamous cell carcinoma of the oral cavity were examined immunohistopathologically as to the responsiveness of the host against its own cancer cells in both biopsy and surgically resected specimens from the same patients. Subpopulations of the infiltrating lymphocytes in cancer tissues were identified on paraffin-embedded serial sections by a modified indirect immunoperoxidase technique (PAB method) in which it was combined with peroxidase-antiperoxidase (PAP) complex and avidin-biotin system with rabbit anti-human B-cell, peripheral T-cell sera. Macrophages were also identified by nonspecific acid esterase staining. T-cells were predominant over B-cells in 26 of 30 tissues in biopsy specimens and 23 of 30 in surgically resected specimens with bleomycin treatment. T-cell infiltration in the peripheral region of the tumor was more prominent than that in the stroma among the cancer nests. T-cells surrounded the cancer nests, occasionally accumulated around the cancer cells, infiltrated at the marginal part of the cancer nests, and frequently produced perivascular massive accumulations. B-cells and macrophages, on the other hand, were almost absent or negligible around cancer tissues. The grade of T-cell infiltration, especially in biopsied specimens, was correlated well to the size of the tumor, and also more marked significantly in patients without cervical lymph node metastasis than in those with lymph node metastasis. Furthermore, there was a significant correlation between the grade of T-cell infiltration at the peripheral region of the invading cancer mass in initial biopsy specimens and the clinical tumor regression rates with bleomycin treatment, but it did not correlate to the surgically resected specimens. These facts suggest that T-cells might inhibit the development and spreading of the cancer cells, and that the T-cell infiltration correlates with the clinical course or prognosis of the oral cancer patients.