Methods of Immunohistochemistry and Its Applications: A Review

Abstract

Hematoxylin and Eosin stain is a standard stain in histopathology that allows for the microscopic analysis of tissue samples for the detection of infections and malignancies. However, problems arise due to the similar appearances of diseases and cells, leading the relevance of Immunohistochemistry (IHC) as a valuable approach. This review highlights the concepts, processes, uses, and future views of IHC, a popular immunostaining approach for detecting specific proteins in tissue slices. Relevant literature was retrieved from PubMed, Scopus, and Web of Science databases using keywords related to immunohistochemistry, biomarkers, and diagnostic applications, with emphasis on studies published in the last decade. Fixation, embedding, sectioning, antigen retrieval, blocking, detection, counterstaining, mounting, and visualization are all part of the multistep IHC process, which is interpreted based on microanatomic distribution and staining intensity. Common IHC problems, such as non-specific staining, tissue artifacts, inadequate inactivation of endogenous peroxidase activity, and cross-reactivity, can have a significant impact on the accuracy and dependability of results, influencing the interpretation of biological findings. Despite its complexities, IHC continues to play important roles in a variety of diseases, including cancers, infectious diseases, neurodegenerative disorders, and muscle diseases. The introduction of digital pathology develops as a gradual improvement, overcoming constraints and enabling more accurate histopathological studies. In conclusion, immunohistochemistry remains a cornerstone of precision diagnostics, connecting molecular insights with morphological context, and its integration with digital pathology continues to improve diagnostic accuracy, reproducibility, and personalized patient care.