Nature and reactivity of staphylococcal enterotoxin A monoclonal antibodies.

Monoclonal antibodies from four clones (C5, C3, B2II, and B2I) directed against staphylococcal enterotoxin A were tested by the indirect enzyme-linked immunosorbent assay and double-gel immunodiffusion (micro-Ouchterlony) assay for the nature of heavy and light chain types. The reactivities of monoclonal antibodies were also tested by indirect enzyme-linked immunosorbent assay with various levels of purified staphylococcal enterotoxin A and various levels (dilutions) of monoclonal antibodies and saturation analysis-competitive indirect enzyme-linked immunosorbent assay. The heavy-chain isotype of monoclonal antibodies was found to be an unspecified subclass of immunoglobulin G1, and the light chain was the kappa type. Monoclonal antibodies from all of the clones exhibited high reactivity and nearly the same affinity to staphylococcal enterotoxin A in saturation analysis-competitive enzyme-linked immunosorbent assay. Purified immunoglobulin G from B2I yielded very high absorbance (1.2) at 405 nm with 1 ng of staphylococcal enterotoxin A as the coating antigen in the enzyme-linked immunosorbent assay. Monoclonal antibodies from B2I also neutralized the biological activity of staphylococcal enterotoxin A when tested by the kitten bioassay.