Methods to quantitate human haptoglobin by complexation with hemoglobin.

Native human haptoglobin isolated from normal human plasma by affinity chromatography on chicken hemoglobin -Sepharose was used as standard antigen. A direct sandwich ELISA for haptoglobin was developed, with human hemoglobin as a capturing agent. The peroxidase activity of the complex was measured as a means of detecting functional haptoglobin. The reactivities of monoclonal antibody vs. polyclonal antisera on the haptoglobin-hemoglobin complex were compared. Adopting a monoclonal antibody, clone 21.7, which is directed to the alpha chain of haptoglobin, a specific method to quantitate the native haptoglobin which can complex with hemoglobin has been developed.