Quantitative slide micro-immunoenzymatic assay (micro-SIA) for antibodies to particulate and non-particulate antigens

A quantitative, minimized version of the slide immunoenzymatic assay (SIA) is described, which is performed with a 5 microliters drop of each reagent on a circular glass surface (3 mm in diameter) delimited by a thin layer of a hydrophobic material. Measurements are done directly, without disturbing the drop of substrate solution while the enzymatic reaction takes place, by means of a vertical beam spectrophotometer. The main features of this quantitative micro-SIA are its simplicity, reproducibility, virtual absence of background and applicability to a large variety of antigen-antibody systems.