Monoclonal antibodies reacting with tryptic hyaluronic acid-binding region and link protein fragments of bovine nasal cartilage proteoglycan.

BALB/c mice were immunized with isolated trypsin-produced hyaluronic acid-binding region (HABR) or HABR/link protein complex from bovine nasal cartilage proteoglycan (PG) aggregates conjugated to keyhole limpet hemocyanin. The monoclonal antibodies (Mabs) raised were characterized by solid-phase ELISA inhibition and SDS-polyacrylamide gel electrophoresis immunoblotting. Nine Mabs react with intact PG monomer, HABR and HABR/link complex. Two of the anti-HABR Mabs appear to be directed to epitopes in or near the HA-binding site of PG monomer; one of these epitopes is insensitive to reduction and alkylation and pronase treatment and is likely to consist of carbohydrate. The remaining anti-HABR Mabs react with PG aggregate, are non-reactive with pronase-treated PG monomer and vary in their reactivity with reduced and alkylated PG monomer. Three Mabs react with link protein-related epitopes. One of these Mabs reacts only with the tryptic link protein fragment, the others also react with PG aggregates and the two native link proteins. Immunological studies of cartilage PG should be facilitated by the availability of Mabs specific for these functionally significant components in native PG aggregates.