Reuse of polystyrene 96 well plates for indirect enzyme immunoassay for detection of antibody to Brucella abortus

One of the major expenses of enzyme immunoassay is the plastic used for immobilization of antigen and for pipette tips. The pipette tips may be washed thoroughly, autoclaved and then reused. The 96 well polystyrene plates are generally used once and then discarded. An indirect enzyme immunoassay for detection of bovine antibody to Brucella abortus is finding application in veterinary diagnostics throughout the world. This assay utilizes lipopolysaccharide extracted from Brucella abortus cells as the antigen bound to polystyrene plates. Because of the physico-chemical stability of this antigen it was decided to attempt to treat the plates to allow their reuse. We describe here a simple method that uses a short duration exposure to a dilute alkaline solution (0.25M sodium hydroxide for approximately 5-15 minutes) to remove the immune complexes from the surface of the wells. Since the lipopolysaccharide antigen is very stable under alkaline conditions, it was found unnecessary to recoat the plates with antigen and it was found that the plates could be reused four to five times (depending on exposure to sodium hydroxide) without reapplication of antigen.