A mouse hybrid cell line producing an antibody to human nervous system-specific gamma gamma enolase has been isolated by fusions between gamma gamma-immunized mouse spleen cells and mouse myeloma cells (P3-NS-1/1-Ag4-1), followed by a screening procedure with an enzyme immunoassay. This particular cell line (E1-G3) has secreted the antibody bearing gamma 2a/kappa immunoglobulin chains. Specificity of the E1-G3 antibody was tested by immunoprecipitation of enolase activities with anti-mouse IgG, and by use of enzyme immunoassay systems for enolase isozymes which consisted of polyclonal rabbit antibodies. The E1-G3 antibody was found to be specific for the gamma subunit of enolase, showing reactivities with human gamma gamma and alpha gamma enolases, and also with rat gamma gamma enolase. However, the monoclonal antibody did not cross-react with the alpha or beta subunit of human enolase.