The Impact of Immunohistochemistry in Histopathological Diagnosis

Janiklas Minky^*
*Correspondence: Janiklas Minky, Department of Urology and Paediatric Urology, Saarland University, 66421 Homburg, Germany, Email:

Keywords

Cell screening • Cytopathologist • Cells • Diagnostic

Introduction

Immunohistochemistry (IHC) has emerged as a powerful adjunct to traditional histopathology, allowing pathologists to detect and visualize specific proteins within tissues. This article explores the significant impact of immunohistochemistry in histopathological diagnosis, emphasizing its principles, applications, advantages, and challenges. Immunohistochemistry is founded on the principles of antigen-antibody interactions. To perform IHC, tissue samples are collected through biopsy or surgery and preserved in a way that retains the antigenic properties of the proteins of interest. Thin tissue sections are then cut and placed on glass slides. These sections are subjected to a series of steps, including deparaffinization, rehydration, and antigen retrieval to prepare them for the application of antibodies. The primary component of IHC is the use of specific antibodies that target proteins of interest. These antibodies are carefully selected to interact with the particular antigen within the tissue. Antibodies can be monoclonal or polyclonal, and they are tagged with a label, typically a chromogen or fluorophore, for visualization. When the antibody binds to the antigen, it forms an antibody-antigen complex, which can be detected under a microscope [1].

Literature Review

The choice of antibodies is critical in IHC as it determines the specificity and sensitivity of the technique. Specific antibodies ensure that only the targeted protein is detected, reducing the risk of false positives. Moreover, the sensitivity of IHC allows for the visualization of even trace amounts of the protein, making it a valuable tool for detecting rare or low-expression proteins in tissues. One of the most significant applications of immunohistochemistry is in cancer diagnosis and subtyping. IHC can help identify the tissue of origin for metastatic tumors, distinguishing, for example, between primary breast cancer that has spread to the liver and primary liver cancer. It is also used to classify and subtype various cancers, such as breast cancer, lung cancer, and lymphoma. This information is essential for determining the appropriate treatment strategies.

IHC is valuable in identifying prognostic and predictive markers in cancer. For example, the presence of certain markers in breast cancer, like the Estrogen Receptor (ER), Progesterone Receptor (PR), and Human Epidermal growth factor Receptor 2 (HER2), can help predict the response to hormonal therapy or targeted therapies. These markers guide treatment decisions, leading to more personalized and effective approaches. Immunohistochemistry is also used in the detection of infectious agents within tissues. In cases of viral infections, such as hepatitis or human immunodeficiency virus (HIV), specific antibodies can be used to identify viral proteins within liver or lymph node tissues. This is especially useful in identifying chronic viral infections or opportunistic infections in immunocompromised patients.

Discussion

IHC is instrumental in diagnosing autoimmune diseases, where the immune system mistakenly attacks the body's own tissues. In conditions like Systemic Lupus Erythematosus (SLE) or rheumatoid arthritis, specific antibodies can be used to detect autoantibodies and immune complex deposition in affected tissues. In neuropathology, IHC helps identify and characterize various neurological disorders, including Alzheimer's disease, Parkinson's disease, and multiple sclerosis. The technique allows pathologists to visualize the distribution of specific proteins, such as beta-amyloid in Alzheimer's disease, which aids in accurate diagnosis and research. Immunohistochemistry is a powerful tool in biomedical research. It allows scientists to investigate the distribution and expression of proteins in tissues, helping to understand disease mechanisms and develop potential therapeutic targets. Researchers can use IHC to explore the effects of experimental treatments on tissues and to validate the findings from other experimental assays. Immunohistochemistry is grounded in the principles of immunology and molecular biology. It involves the use of specific antibodies to target and detect antigens within tissue sections. The process begins with the preparation of tissue samples, which are then subjected to a series of steps, including fixation, antigen retrieval, blocking, incubation with primary and secondary antibodies, and finally, visualization. The key to IHC's success lies in its specificity, enabling the identification of specific proteins or antigens within the tissue [2].

IHC is widely used in cancer diagnosis and classification. By examining tissue samples, pathologists can determine the origin of a tumor, its differentiation state, and predict its behavior. For example, Estrogen Receptor (ER), Progesterone Receptor (PR), and Human Epidermal growth factor Receptor 2 (HER2) IHC assays are crucial in the diagnosis and management of breast cancer. Similarly, IHC staining for cytokeratins, CD45, and CD20 aids in distinguishing between different types of carcinomas and lymphomas. IHC can also be employed to identify infectious agents in tissues, aiding in the diagnosis of diseases caused by viruses, bacteria, or fungi. For instance, the presence of viral antigens in liver tissue can be detected through IHC to diagnose viral hepatitis. IHC is used to detect autoantibodies and immune complex deposits in various autoimmune diseases, such as Systemic Lupus Erythematosus (SLE) and Rheumatoid Arthritis (RA). This aids in confirming the diagnosis and understanding the underlying pathology [3,4].

IHC can provide predictive information about the efficacy of certain treatments. For example, in breast cancer, IHC analysis of HER2 expression helps identify patients who may benefit from targeted therapies, such as trastuzumab. IHC can identify tissue abnormalities that are not apparent with routine H&E staining. This is especially valuable in identifying neurodegenerative diseases and disorders of the nervous system, such as Alzheimer's disease and Parkinson's disease. IHC can provide valuable information regarding the prognosis of certain diseases. For example, in colorectal cancer, the presence of the protein p53 in tissue samples can be indicative of a worse prognosis. IHC is an essential tool in medical research for discovering and validating biomarkers associated with diseases. This information can be used to develop targeted therapies and improve patient outcomes. IHC allows for the precise localization of proteins within tissues, enhancing the specificity of diagnosis. This is particularly crucial in distinguishing between different cancer types and subtypes [5,6].

Conclusion

Immunohistochemistry is a technique that employs antibodies to detect specific proteins in tissue samples. It relies on the principles of antigenantibody interaction. The process begins with the preparation of tissue sections, followed by the application of primary antibodies targeting the protein of interest. Subsequently, secondary antibodies conjugated with detectable markers, such as enzymes or fluorescent dyes, are used to bind to the primary antibodies. These results in the formation of visible or quantifiable signals at the site of the protein of interest, making it possible to identify, localize, and quantify the presence of specific biomarkers within the tissue.

Acknowledgement

None.

Conflict of Interest

There are no conflicts of interest by author.

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