抄録
A murine monoclonal antibody of the immunoglobulin M subclass, termed M1C, was prepared by fusion of P3X63Ag8U.1 mouse myeloma cells with spleen cells from BALB/c mice immunized with the recently established human medulloblastoma cell line MED-3. MED-3 cells are unique in expressing both neuronal and glial phenotypes. The antigen recognized by M1C was expressed predominantly in the cytoplasm of antigen-bearing cells, but was also present in lower concentration on the cell surface. Flow cytometry showed M 1 C binding to MED-3 cells increased during the G2/M phase, and decreased after induction of differentiation with N6, O2-dibutyryl cyclic adenosine monophosphate. Biochemical analysis indicated that M1C recognized a 25-kd protein. Immunoperoxidase staining of cultured cell lines showed that although M 1 C recognized a large panel of malignant tumorderived cell lines, the staining of malignant glioma-derived cell lines was strongest. Immunohistochemical examination of various human tissues revealed that M1C reacted strongly with malignant gliomas but did not recognize low grade astrocytomas, neuroblastomas, or tumors from other organs. Cross-reactivity with normal tissues was restricted to peripheral blood lymphocytes. The immunoreactivity of M1C was quite different from the two previously described monoclonal antibodies against medulloblastoma. M 1 C is the first reported MoAb against medulloblastoma, which recognizes a differentiation and proliferation-dependent antigen expressed in malignant gliomas in particular, and may be useful in determining the differentiation and proliferation features of medulloblastomas and gliomas.
