An immune hemagglutination procedure with very high sensitivity applied to the detection of hepatitis B antibody and antigen and immune complex.

An immune agglutination procedure is described in which red cells are coated with antigen and agglutination is observed after a short incubation with antibody in reagent serum. Conversely, the cells may be coated with antibody and used to test for the presence of antigen. Treatment of the reagent serum with cobra venom factor results in inhibition, and there is a marked lo-s of sensitivity with cells pretreated with formalin or chromic chloride, suggesting that C3 and some type of reactive sites on the cells are required. The distinctive features of the new procedure are that incubation time is very short, sensitivity is several orders of magnitude higher than with other related tests, and, within some limitations, bovine (steer) red cells with bovine serum can be used as an alternative to human red cells with human serum. It is necessary to remove an inhibitor from the reagent serum, human or steer. While the mechanism of the procedure needs further elucidation, the findings reported here suggest that it ought to be sufficiently sensitive to detect hepatitus B antigen if present in virtually any blood sample. With appropriate modifications it should be useful for blood donor screening, diagnosis, and for studying many other antigen-antibody systems.