Production and characterization of monoclonal antibodies against the "brain-specific" proteins 14-3-2 and S-100.

We have raised mouse hybridomas that secrete monoclonal antibodies against bovine brain-specific proteins 14-3-2 and S-100, and we have characterized the antibodies by immunoperoxidase and immunofluorescence methods in sections and in tissue cultures of rat brain. One monoclonal antibody to 14-3-2 (E8.F9) has been found to react strongly with bovine 14-3-2 and with rat neuron-specific enolase in an enzyme-linked immunosorbent assay (ELISA) and to react weakly with rat nonneuronal enolase. This pattern of specificity is reflected in strong neuronal labeling and occasional weak glial labeling in immunocytochemical preparations. After appropriate tissue fixation, E8.F9 could be shown to be localized primarily to the cytoplasm of neurons; with less adequate fixation nuclear labeling was also seen. A monoclonal antibody to the calcium binding protein S-100 (G12.B8) reacted strongly with bovine S-100 in an ELISA and with the major protein bands in electrophoretically separated S-100. In immunocytochemical preparations G12.B8 labeled the cytoplasm of astrocytes. Both antibodies are of the IgG1 subclass. Because of its specificity, the antibody against the S-100 protein promises to be useful as an immunological marker for astrocytes in the adult animal and in mature tissue cultures of brain cells. Although it has been thought that the generally low levels and relatively late appearance of S-100 during ontogeny may restrict its usefulness as a marker for developing astrocytes, preliminary immunocytochemical evidence indicates that G12.B8 selectively labels radial glial cells and astrocytes or astrocyte precursors as early as, or even earlier than, antibodies against the glial fibrillary acidic protein. The antibody against neuron-specific enolase is likely to be of limited use as a neuronal marker because of its crossreactivity with nonneuronal enolase.