[Immunohistology of tumor tissue in local administration of recombinant interleukin-2 in head and neck cancer].

Biopsied specimens from patients treated by local administration of rIL-2 were examined immunohistologically. Lymphocytes infiltrating into the cancer tissue before and after administration of rIL-2 were observed on paraffin embedded sections by Hematoxilin Eosin (HE) stain in relation to the clinical effect. And their subsets were identified on frozen sections by Avidin Biotin peroxidase Complex (ABC) method using monoclonal antibodies to examine what kinds of effector cells were induced and increased in the tumor site by rIL-2 in vivo. The intensity of increasing of tumor infiltrating lymphocytes (TIL) was correlated with the clinical effect of local administration of rIL-2. Tumor Infiltrating Lymphocytes were mainly T lymphocytes, of which Leu-2a+ cells (suppressor/cytotoxic T cells) and Leu-3a + 3b+ cells (helper/inducer T cells) were almost equally observed. Leu-2a+ cells were considered to be mainly cytotoxic T lymphocytes because few Leu-2a+ cells were stained with anti-Leu-15 antibody. After administration of rIL-2, marked infiltration of T lymphocytes was observed and there was no obvious different response in degree of infiltration between Leu-2a+ cells and Leu 3a + 3b+ cells. Furthermore, IL-2 receptor+ T lymphocytes (activated T lymphocytes) were increased after administration of rIL-2. And natural killer (NK) cells were slightly observed and also increased after administration of rIL-2. These findings suggest local administration of rIL-2 has possibility to induce cytotoxic T lymphocytes, to increase NK cells and to activate these lymphocytes in vivo.