RESUMO
In this review, some light is thrown on various labeled immunoassays that depend on antigen-antibody [Ag-Ab] reactions, including immunofluorescence, radioimmunoassay, and enzyme immunoassay [EIA or ELISA]. Their definitions, principles, and applications are described, then they are discussed chronologically to show their stepwise development that led finally to full automation. Enzyme labeled immunoblot assays [Western blot, blot spot, and recombinant immunoblot assay], and luminescence [bioluminescence and chemiluminescence] are also discussed chronologically. Labeled assays, that do not involve Ag-Ab reaction but rather, utilizing biotin-steptavidin [BS] interaction and probe-target DNA interaction, and described, together with their applications for DNA/RNA detection and genotyping. Finally, included in the discussion were some luminescent labeled techniques that utilitze the immune Ag-Ab reaction together with non-immune BS reaction, such as the luminescent oxygen channeling immunoassay, and its commercialized AlphaLISA, both eliminate the washing steps without sacrificing high sensitivity, or wide dynamic range