Immunohistochemical study on the distribution of alpha and beta subunits of S-100 protein in brain tumors.

The immunohistochemical distribution of alpha and beta subunits of S-100 protein (S-100 alpha, S-100 beta, respectively) in 138 cases of human brain tumors was investigated by the avidin-biotin immunoperoxidase method. Brain tumors can be divided into four groups: group 1 [S-100 alpha (+) and/or S-100 beta (+)]; astrocytoma, glioblastoma, ependymoma, subependymoma, oligodendroglioma, choroid plexus papilloma, gangliocytoma, meningioma, chordoma, malignant melanoma. Group 2 [S-100 alpha (+) and S-100 beta (-)]; pineoblastoma, pituitary adenoma, craniopharyngioma, rhabdomyosarcoma. Group 3 [S-100 alpha (-) and S-100 beta (+)]; acoustic Schwannoma. Group 4 [S-100 alpha (-) and S-100 beta (-)]; medulloblastoma malignant lymphoma, germinoma. The S-100 beta immunoreactivity pattern in brain tumors was similar to those obtained using conventional anti-S-100 protein sera. In the first group of brain tumors both the number of positively stained tumor cells and the staining intensity were generally greater for S-100 beta than for S-100 alpha with a few exceptions including one gemistocytic astrocytoma, one subependymoma, one malignant melanoma, and some cases of glioblastomas. As to the relationship between malignancy and S-100 protein in glioma, S-100 beta immunoreactivity decreased according to degree of malignancy, while that of S-100 alpha varied, suggesting a heterogeneity of tumor cells in glioblastomas. Immunostaining for S-100 alpha and S-100 beta might become a useful diagnostic procedure in brain tumors and may give us more detailed and precise data of S-100 protein in brain tumors.