This assay applies an enzyme-linked immunosorbent assay (ELISA) technique. A purified mouse IgG has been pre-coated onto the wells of microplate. Standard (rabbit anti-mouse IgG) and specimens are added into the appropriate wells simultaneously with a HRP-labelled mouse IgG, and incubated. The Human Anti-Mouse Antibody (HAMA), if present, will bind with the mouse IgG which coated on the wells and HRP- labelled mouse IgG as well, forming a "Sandwich". Following a wash to remove any unbound substance, a substrate solution is added. The developed colour is directly proportional to the anti-mouse antibody concentration in the specimen and Standard samples.