Application of ELISA and ELADA Assay (Double Substrate Immunoassay) to Red Blood Cell Antigens

Abstract

A double substrate immunoassay was developed that allows simultaneous quantitation and localization of [human] blood cell surface antigens. The assay can be used to quantitate surface antigens, or the titer of antisera specific to cell-surface antigens, on the red blood cell. The assay was adapted to the study of both D antigen and erythrocyte membrane (EM) antigen, which were uniformly dispersed over the surface of the cell. The number of EM antigen per cell appeared to be approximately 20 times that of the D antigen. For typing antisera, this assay makes it feasible to express antibodies in absolute units (.mu.g antibody) rather than conventional dilution titers, and thus offers a simpler means of rapidly comparing antisera.