Identification of novel neural- and neural retina-specific antigens with a monoclonal antibody.

A fluorescence-activated cell sorter screening method has been used to identify hybridomas that secrete monoclonal antibodies that can bind to viable subpopulations of embryonic chicken neural retina cells. One monoclonal antibody, C1H3, recognizes two nervous tissue-specific polypeptides that exhibit distinct developmental patterns. The monoclonal antibody reacts with a 140-kilodalton (kDa) polypeptide that is present at early stages of development (day 7) but is detected by immunoblotting in only negligible amounts at later times (day 17). In contrast, a 170-kDa polypeptide is first detectable by immunoblotting at day 10 and is the predominant C1H3 antigen at day 17. Analysis of proteolytic fragments of the two proteins indicates that the polypeptides are distinct molecules that share a common antigenetic determinant. Both polypeptides are neural-specific; the 140-kDa polypeptide appears to be retina-specific, while the 170-kDa polypeptide is also present in other areas of the nervous system. Metabolic labeling of retina cells in situ at early embryonic stages reveals only the synthesis of the 140-kDa polypeptide. When such cells are dissociated and labeled in vitro, they synthesize primarily the 170-kDa polypeptide. Thus, the differential rate of synthesis of these two polypeptides is controlled by environmental factors that possibly include cell-cell contacts or an unknown systemic factor. The 140-kDa polypeptide is a unique marker for early neural retina cells.