Immunohistochemistry is a valuable tool for the identification and visualization of tissue biomarkers in the form of antigens in biological research and clinical diagnostics. Immunohistochemistry can characterize various biological processes or pathologies, such as wound healing, immune response, tissue rejection and regeneration, and tissue-biomaterial interactions. Specific antigen-antibody reactions can localize key molecules (eg, cytokines, enzymes, transcription factors) associated with each process within the tissues. Combined use of antibodies for such molecules and cell type-specific markers can identify the major cell sources and examine cell phenotypic changes (eg, differentiation, activation, proliferation). Careful validation and protocol optimization, as well as selection of the proper microscopy methods (eg, bright-field vs. fluorescence microscopy), enable procurement of specific and reproducible results. In addition, various newly developed fluorescent dyes, excellent color contrast, high resolution imaging, and the possibility of simultaneous multicolor imaging make immunofluorescence microscopy a convenient tool for studying pathobiological processes at the cellular level. This chapter provides a general introduction to immunohistochemistry, including the background information about antibody-antigen interaction, labeling techniques, tissue processing, basic immunohistochemical methods and established protocols, and data interpretation. It also discusses the impact of immunohistochemistry in biomaterial research and current understanding of the pathological processes of wound healing after implantation.
