Quantitation of human haptoglobin by ELISA system based on streptococcal haptoglobin receptors

Streptococcus pyogenes cells with binding properties for human haptoglobin were used for quantitative determination of the acute phase protein, haptoglobin in various biological fluids. The S. pyogenes cells with protein surface antigen T4 served as solid phase in a microtitre ELISA system. After binding to the bacteria the amount of haptoglobin could be quantified by polyclonal or monoclonal antibodies. The constructed ELISA proved to be sensitive and correlated well with a conventional peroxidase method and with an immunoassay based on hemoglobin binding to haptoglobin.