Reacts strongly with human S100B, and weakly or very weakly with S100A1 and S100A6, respectively. S100 from ox brain has been used for the immunization. Z0311 labels glial cells in the brain and ependymal cells. Moreover, Schwann's cells of the peripheral nervous system are positive. Results aid in the classification of tumors in central and peripheral nervous system, such as schwannomas, ependydomas as well as in different grades of astrogliomas, also including glioblastomas. A large proportion of cells in human tumors originating from different salivary glands are labeled by anti-S100. The antibody is also a useful aid for classification of malignant melanocytic tumors of the skin and metastases of human malignant melanomas.