The use of monoclonal antibodies with colloidal gold-labeled probes in postembedding immunoelectron microscopy

This article focuses on procedures for the use of monoclonal antibodies (MAb) in immunoelectron microscopy (IEM) for the subcellular localization of antigens or to relate function with structure in prokaryotic and eukaryotic cells using postembedding immunoelectron microscopy techniques. The use of MAbs greatly increases the specificity and quality of information when used in combination with gold-labeled probes. Because of its specificity, the reactivity of MAb may be very sensitive to antigenic changes resulting from the process of sample preparation when performing IEM studies. Specific protocols for each particular combination of epitope/MAb must be usually specifically devised, since it is impossible to predict an experimental system that will successfully preserve structures and antigenic determinants for every combination. In this article, we discuss critical technical aspects that usually result in improved resolution when the procedure is used to identify structure in diverse prokaryotic and eukaryotic cells.