The application of immunoblotting to the phenotyping of haptoglobin.

An immunoblotting method for phenotyping haptoglobin in serum and bloodstains has been developed. Haptoglobin isoproteins were separated by polyacrylamide gradient gel electrophoresis and then transferred to nitrocellulose by electroblotting. The use of 1 mm gels facilitated more rapid and effective transfer than conventional 3 mm thick gels. Nitrocellulose blots were developed by double antibody enzyme immunoassay. The detection limit for serum and bloodstains was improved 16 times compared to conventional staining using O-tolidine. The method could detect haptoglobin phenotypes from 0.001 microliter of whole blood. This detection limit is approximately 8 times lower than that of group specific-component analysis by immunoblotting.