Application of an enzyme-linked immunosorbent-inhibition assay to quantitate the release of KS peptides into fluids of the rat subcutaneous air-pouch model and the effects of chondroprotective drugs on the release process.

The effects of the chondroprotective agents (Arteparon, SP-54 and DH40J) on the release of proteoglycan degradation products (as keratan sulphate peptide fragments) from articular cartilage implanted into rat subcutaneous air pouches have been investigated by using an enzyme-linked immunosorbent-inhibition assay (ELISIA). The ELISIA technique was capable of quantitating the keratan sulphate peptides (KS peptides) in fluids within the range of 100-2,000 ng/ml by using the monoclonal antibody line 1/20/5-D-4 and human articular cartilage KS peptides as standard reagents. It was found that the levels of KS peptides present in the air-pouch fluid of rats treated with the chondroprotective drugs was significantly less than in fluid aspirated from the pouches of non-drug-treated control animals. On the basis of these findings we suggest that the assessment of KS peptide by ELISIAs may provide a useful means of monitoring proteoglycan breakdown products in biological fluids (e.g. synovial fluids or blood) and for evaluating the effects that antiarthritic drugs may have on this process.