Single incubation multilayer immune technique.
A new method termed the 'single incubation multilayer immune technique (SIMIT)' is described which features two striking advantages over standard immunoassay techniques: shorter assay time and superior assay sensitivity. Using standardized, optimized amounts of ligand (e.g., antibodies) and anti-ligand (e.g., anti-antibody) it is possible to co-incubate these two reactants so that during a single incubation step multiple layers of immunoreactants are formed thereby resulting in enhanced assay sensitivity. Depending upon the application, SIMIT improves detection levels by about 10-20-fold. This report describes the use of SIMIT for two completely different assay systems: (a) indirect enzyme-linked immunosorbent assays, and (b) unlabeled enzyme immunoassays. However, SIMIT should be applicable to a large variety of other assay systems.