Immunohistochemistry (IHC) has revolutionized the field of pathology and molecular diagnostics by enabling the visualization of antigens in tissues. Through identifying the location and quantity of antigens like proteins, IHC has provided crucial insights into disease mechanisms and biomarkers. This has accelerated drug development and personalized medicine approaches.
Detection of Tumor Markers Advances Cancer Treatment
A major application of IHC is in oncology for the detection of tumor markers. Cancer cells often overexpress or underexpress certain proteins compared to normal cells. IHC allows pathologists to test for these tumor markers in biopsy or surgical specimens. For example, detection of estrogen and progesterone receptors informs treatment decisions for breast cancer. Similarly, HER2 testing guides HER2-targeted therapies. IHC testing of PD-L1 expression helps identify patients that may benefit from immunotherapy. As new tumor markers are discovered, IHC plays a key role in validating their clinical significance and incorporating them into routine patient management algorithms.
Uncovering Cell Types Advances Neuroscience
In neuroscience, IHC plays an indispensable role in cell classification and mapping gene expression patterns in the brain. Identifying the specific cell types expressing certain proteins has advanced our understanding of brain development, function and diseases. For example, IHC revealed that dopamine and serotonin are expressed by distinct neuronal populations, key insights for neuropsychiatric conditions. IHC is also employed to probe for disease proteins linked to neurological conditions like Alzheimer's and Parkinson's diseases. Neuropathologists rely on IHC to help establish definitive diagnoses. As our knowledge of the molecular underpinnings of the brain increases, so too does the utility of IHC.
Elucidating Pathogenic Mechanisms Informs Treatment Design
IHC has provided critical insights into infectious disease pathogenesis. It allows visualization of viral, bacterial or parasitic antigens within infected tissues, revealing localization patterns and host response dynamics. Combined with other techniques, IHC has elucidated mechanisms of host-pathogen interactions. For example, IHC studies of SARS-CoV-2 infection showed viral spike protein localization in the lungs and helped establish its respiratory transmission route. Understanding pathogenic lifecycles and tissue tropism through IHC informs vaccine and drug design. IHC is also applied to uncover resistance factors in antibiotic-resistant pathogens to aid new antibacterial development efforts.
Revolutionizing Histocompatibility Testing Boosts Transplant Success
In the field of transplantation, IHC has played a pivotal role in developing sensitive techniques for histocompatibility testing between donors and recipients. It enables identification of human leukocyte antigen (HLA) antigens expressed on cells and tissues. Accurate HLA typing by IHC improves compatibility matching for organ, bone marrow and stem cell transplants, reducing rejection risks. IHC has also helped identify non-HLA antigens important for transplantation outcomes. Continued IHC advances will further individualize donor-recipient matching and immunosuppressive regimens, translating to higher success rates for life-saving transplants.
Automation and Multiplexing Advance High-Throughput Applications
While traditionally an investigator-led technique, automation and digitalization are revolutionizing IHC applications. Entire staining processes can now be automated on large sample batches with precise reagent delivery and standardization. Digital imaging and analysis techniques enable objective, quantitative readouts at high throughput. Multiplexing IHC approaches allow simultaneous detection of several antigens in a single tissue section using unique fluorescent labels. Such technical advances are powering high-content analysis for drug screening, biomarker validation studies and clinical cohort research at an unprecedented scale. This is fueling data-intensive approaches in precision medicine.
Advancing IHC Beyond Research Into Routine Diagnostics
Despite being pioneered over half a century ago, IHC continues to evolve rapidly with new antigen targets, probe technologies and imaging strategies. Beyond core research applications, automated IHC platforms are being translated into clinical setting for routine molecular diagnostics. This delivers comprehensive prognostic and predictive biomarkers to every patient through an objective, standardized test. Global healthcare providers are recognizing IHC’s critical role in individualizing treatment plans. With advances in automation, test menu, and regulatory approvals - IHC tests are becoming widespread companion diagnostics guiding clinical decision making. Overall, IHC has profoundly influenced our understanding of human disease and will continue refining next-generation diagnostics to unlock personalized therapies.
Conclusion
Immunohistochemistry is a widely used technique across research and clinical pathology that provides valuable information about protein expression and cellular localization patterns in tissue samples. With rigid quality control measures and continued method advancements, IHC will continue to serve as an indispensable tool for biomedical discovery and disease diagnosis.
The global immunohistochemistry market size is expected to reach a value of USD 3.2 billion by 2027, expanding at a CAGR of 7.8%, according to a new report by Radiant Insights, Inc.
IHC has become a crucial technique and is widely applied in the diagnosis of several chronic diseases such as cancer, infectious diseases, and cardiovascular diseases (CVDs).
Thus, a rise in the incidence of these chronic diseases has led to an increase in the demand for IHC techniques.
According to 2018 data published by WHO, globally, cancer was one of the leading causes of mortality, and in 2018 around 9.6 million deaths were registered due to cancer.
Additionally, in June 2019, the U.S. FDA approved the expanded use of Agilent Technologies’ PD-L1 IHC 22C3 pharmDx assay for the detection of head and neck squamous cell carcinoma (HNSCC).
This product is used in patients receiving treatment with Merck and Co., Inc.’s Keytruda (Pembrolizumab).
