Monoclonal antibodies distinguish subtypes of retinal horizontal cells

Sixteen hybridomas have been identified that secrete antibodies specific to horizontal cells in the carp retina. The hybridomas have been classified into three groups based on their antibody staining patterns: group I, staining associated with all horizontal cells; group II, staining associated with the most abundant subtype of horizontal cell (CH1); and group III, staining associated with other subtypes of horizontal cells. Most of the hybridomas fall in group II; some of these antibodies stain the entire horizontal cell, but others are specific only to the cell perikarya and do not stain axonal processes. Our results suggest that there are surface molecules specific (i) to all retinal horizontal cells, (ii) to individual subtypes of horizontal cells, and (iii) to portions of horizontal cells. Furthermore, a group II antibody, which recognizes a 48- to 50-kDa membrane protein, has been found to provide a substrate selective for horizontal cell growth. Horizontal cells plated on coverslips coated with this antibody remain healthy in culture and extend long and elaborate processes for at least 3 weeks.