Covalent coupling of proteins to erythrocytes by isocyanide. A new, sensitive and mild technique for identification and estimation of antibodies by passive hemagglutination.

A mild method for covalent coupling of protein-antigens to the surface of red blood cells (RBC) is described. The method is based on the formation of covalent bonds between aldehyde groups of oxidized RBC and amino or carboxyl groups of proteins in the presence of isocyanide. Very low concentrations of antibodies (8-30 ng/ml) could be detected in antisera with the specifically sensitized RBC as reagents in passive hemagglutination with no or very low non-specific agglutination.