ABSTRACT
Molecular morphologists and immunohistochemists use polyclonal antibodies (PCAs) to (1) specifically detect substances in tissue sections (immunohistochemistry), cytological preparations (immunocytochemistry), or on Western blots, as “primary antibody”; (2) detect in situ the location of specific antigen-antibody-complexes formed in immuno(histo/cyto)chemistry; or (3) show the location of the specific (reporter-molecule-labeled) hybrids formed by in situ hybridization or in situ PCR on sectioned tissue, in cytology, or on blots. PCAs are usually the reagent of choice for “secondary” antibodies or antibodies binding to locations of reporter molecules. Instead of “primary” antisera, monoclonal antibodies (MCAs) are increasingly used for this purpose. It can be foreseen that pools of different MCAs, all recognizing different epitopes of the same antigen (class), will replace PCAs in many of these applications because their mass production in bioreactors will become more cost effective. For the time being, however, PCAs are still widely used.
