Technical Aspects of Immunohistochemistry

**3**

**Chapter 1**

**Abstract**

background

**1. Introduction**

Detection Systems in

Immunohistochemistry

choosing an appropriate detection system for IHC applications.

**Keywords:** immunohistochemistry, antibody, detection systems, sensitivity,

Immunohistochemistry (IHC) represents a way to build a picture of particular distribution and localization of molecular markers within cells and in the proper tissue context and is a powerful tool that provides important diagnostic, prognostic, and predictive information supplemental to the morphological assessment of the tissues. Although less sensitive quantitatively than such immunoassays as western blotting or ELISA, IHC enables observation of molecular signature in the context of intact tissue. In its very simplified method, IHC visualizes target antigens by using target-specific antibodies tagged with appropriate labels. However, lack of need for labeling of molecular marker-specific primary antibodies and higher sensitivity made indirect staining methods as the preferred staining method. The need for more sensitive detection systems in case of minimally expressed markers was a provocative factor that eventually led to the emergence of next generations of IHC detection methods with the hope to amplify staining signal. IHC

Immunohistochemistry (IHC) is a process of selectively imaging antigens in cells or tissue sections by exploiting antibody specificity. This technique is widely used in diagnostic pathology and research experiments for tracking specific molecular markers characteristic of a particular cell type or cellular events such as cancerous cell development, cell proliferation, or apoptosis. Visualizing the target antigen following an antibody-antigen interaction is accomplished by different detection systems. In the simplest instance, primary antibody directly conjugated to an enzyme is responsible for both specifically binding to the antigen and catalyzing a color-producing reaction. Alternatively, complex detection systems could be designed to profoundly improve minimal detection level of the antigen. During the past years, there has been a considerable improvement in designing and introduction of new and highly sensitive detection systems. The choice of an IHC detection system is a compromise of a variety of variables including desired sensitivity, cost, and the time needed for an IHC staining to be performed. This chapter covers the immunohistochemistry detection systems with emphasis on their principle, history, advantages, and limitations and delineates factors needed to be considered for

*Sorour Shojaeian, Nasim Maslehat Lay* 

*and Amir-Hassan Zarnani*
