Immunohistochemistry (IHC) is a laboratory technique pathologists use to identify specific components within cells and tissues, aiding in disease diagnosis. It operates on the immune system’s principle of specific binding, making it a powerful diagnostic tool in pathology.
How IHC Works
IHC operates on the principle of antibody-antigen recognition. Antigens are specific molecules, often proteins, found within tissue cells that can indicate disease. Antibodies, proteins produced by the immune system, bind precisely to these antigens, much like a lock and key.
The process begins with obtaining a tissue sample, usually through a biopsy, which is then preserved and prepared. Specialized antibodies, designed to target specific antigens, are applied to this tissue. If the target antigen is present, the antibody will attach.
To make this binding visible, a detection system is employed. This involves linking the antibody to an enzyme or a fluorescent dye. If an enzyme is used, a substrate is added, which reacts to produce a color change, staining the tissue. Fluorescent dyes emit light when viewed under a special microscope. Pathologists then examine the stained tissue to identify the antigen’s location and amount, providing diagnostic information.
What IHC Helps Diagnose
IHC is widely used in medical diagnostics for disease identification and classification. A primary application is cancer diagnosis. It helps pathologists determine the specific cancer type, distinguishing between subtypes like breast cancer by identifying markers such as estrogen receptor (ER), progesterone receptor (PR), and HER2. IHC also classifies lymphomas and leukemias, and identifies the origin of metastatic tumors when the primary site is unknown.
Beyond cancer, IHC identifies infectious agents. It detects specific viral or bacterial proteins in tissue samples, diagnosing conditions caused by organisms difficult to identify otherwise, such as cytomegalovirus or human papillomavirus. The technique also diagnoses neurodegenerative conditions, like Alzheimer’s disease, by detecting abnormal protein accumulations. IHC assists in guiding treatment decisions by identifying receptors or markers that indicate how a patient’s disease might respond to specific therapies, supporting personalized medicine.
Why IHC is Indispensable
Immunohistochemistry is an important tool in modern medicine, complementing traditional diagnostic methods. It provides specific molecular information while preserving tissue structure, allowing pathologists to see where specific proteins are located within cells and tissues. This spatial context is important for accurate diagnosis and understanding disease progression.
The precision of IHC contributes significantly to accurate disease classification, which directly impacts patient care. It enables clinicians to differentiate similar conditions and determine tumor aggressiveness and behavior. This detailed information is important for establishing prognosis and developing effective treatment plans, including identifying patients who benefit from targeted therapies. IHC’s ability to reveal specific biomarkers also supports the advancement of personalized medicine, tailoring treatments to an individual’s disease characteristics.