This recent study enlightens two immunoassays that can be helpful in detecting endogenous peptide biomarkers and shows a great specificity for osteoarthritis. An early diagnosis of biochemical tests can be helpful in the prevention of OA. 

Osteoarthritis (OA) is the very common chronic joint disease that is usually diagnosed at relatively advanced stages when there is irreparable damage to the joint(s). Recently, two novel biomarkers have been identified, C3f and V65 which appear to be OA-specific and therefore potential markers of early disease. The development of immunoassays has been reported for the quantitative measure of these two novel biomarkers.

Monoclonal and polyclonal antibodies were generated by immunizing rabbits and mouse respectively with peptide-carrier conjugates of V65 and C3f. Assays were validated using serum from OA patients and controls and the affinity-purified antibodies were used for immunoassays development.

The developed ELISA showed very sharp recovery of about 96% (up to) for C3f and V65 peptides depending on serum dilutions with a coefficient of variation (CV) <10%. The inter- and intra- assay CVs for V65 and C3f were 4.2–10.3%  and 1.3–10.8% respectively. Both the assays were insensitive for measurements of the peptides in patients, and the use of different signal amplification systems still was not able to increase the sensitivity of the assay 

Two immunoassays are developed for measurements of C3f and V65 peptides biomarkers discovered by our earlier proteomic study. These assays could detect the endogenous peptides in serum samples from patients and controls but lacked sensitivity for accurate measurements of the peptides in OA patients. The study also highlighted the difficulties and challenges of validating biomarker from proteomic studies and demonstrated how to overcome the technical challenges associated with the development