Abstract: The present invention is directed to biochemical assay methods, which re-use a hapten-immobilized test probe and reagents for quantitating an analyte or measuring kinetic binding in different samples, anywhere from about 3 to 20 times, while maintaining acceptable assay performance. The methods use a conjugate solution either comprising (i) an anti-hapten antibody and a capture antibody against an analyte, or (ii) an anti-hapten antibody and streptavidin, in each cycle and regenerate the hapten-coated test probe by dipping the test probe in an acidic solution having pH about 1-4, optionally further dipping in a DMSO solution, after the completion of each cycle of reaction. The robustness of the hapten-immobilized solid phase allows utilization of denaturation reagents for efficient elution of the immune complexes after each cycle without compromising the binding activity of the hapten on the solid phase.

Abstract: Methods of enhancing production of cytokines such as IL-10 by, for example, optimizing refolding conditions, are described. The methods provide an efficient, cost-effective means of manufacturing IL-10 on a commercial scale.