Passive gold agglutination. An alternative to passive hemagglutination

A method is described for coating colloidal gold with protein for use in passive agglutination. Coating of the gold is quick, reproducible and the sterile filtered product is stable over a long period of storage at 4 degrees C. Colloidal gold coated with each of the 4 subclasses of human IgG was tested with rabbit, monkey and goat antisera and found to be compatible with each. The visual properties of coated gold particles resemble blood cells and appear to be equally sensitive.