The main difference between in-situ hybridization and immunohistochemistry is that in-situ hybridization involves the detection of a particular protein in thin tissue sections or cells mounted on slides, whereas immunohistochemistry involves the detection of a specific sequence or region of DNA or RNA.
Generally, in-situ hybridization and immunohistochemistry are valuable tools in localizing the cellular expression of specific proteins or RNA transcripts within the tissue.
Key Areas Covered
1. What is In-situ Hybridization
– Definition, Characteristics, Importance
2. What is Immunohistochemistry
– Definition, Characteristics, Importance
3. Similarities Between In-situ Hybridization and Immunohistochemistry
– Outline of Common Features
4. Difference Between In-situ Hybridization and Immunohistochemistry
– Comparison of Key Differences
Key Terms
Immunohistochemistry, In-situ Hybridization
What is In-situ Hybridization
In general, in-situ hybridization (ISH) is a technique that detects the localization of a specific segment of nucleic acid within a tissue section. Therefore, it detects specific DNA, RNA, and modified nucleic acids in tissue sections or mounted cells on a slide. In addition, in-situ hybridization uses probes to detect the complementary nucleic acid sequence present in the sample. Double-stranded DNA (dsDNA) probes, single-stranded DNA probes (ssDNA), RNA probes (riboprobes), and synthetic oligonucleotides are the main types of probes used in in-situ hybridization.
Figure 1: RNA in situ hybridization – Human Melanoma FFPE Tissue Section
Furthermore, these probes are labeled with radioactive labels such as 32P, 35S, and 3H or non-radioactive labels such as biotin, digoxigenin, and fluorescent dyes. Usually, in-situ hybridization can detect the morphology and population structure of microorganisms in microbiology. In pathology, it is important for pathogen profiling, and abnormal gene expression. Moreover, gene expression profiling in embryonic tissues is the application of in-situ hybridization in developmental biology. In karyotyping and phylogenetic analysis, patterns of individual chromosomes and chromosomal aberrations can be detected by in-situ hybridization. Moreover, it is important in chromosomal mapping.
What is Immunohistochemistry
Immunohistochemistry (IHC) is an important application of antibodies to determine the distribution of a particular antigen in health and disease. Therefore, it is important in the detection of specific tumor antigens and cancer. More importantly, immunohistochemistry is important in the detection of benign and malignant tumors using specific tumor markers. Normally, the technique can identify the cell types and the origin of metastasis.
Figure 2: Immunostaining
Moreover, immunohistochemistry uses monoclonal or polyclonal antibodies to detect the specific antigens in the tissues. Primary and secondary antibodies are the two types of antibodies in immunohistochemistry assay. Generally, primary antibodies bind with the specific antigen in the tissue sample. However, secondary antibodies bind to the primary antibodies. The linker molecules in the secondary antibodies such as biotin help in the detection of the binding of the secondary antibodies.
Similarities Between In-situ Hybridization and Immunohistochemistry
- In-situ hybridization and immunohistochemistry are two important tools in the detection of cellular expression.
- Both techniques can detect localized cellular expression in thin tissues or in cells mounted on slides.
Difference Between In-situ Hybridization and Immunohistochemistry
Definition
In-situ hybridization refers to a technique used to localize a specific sequence of nucleic acids in a biological sample while immunohistochemistry refers to a technique that uses antibodies to check certain antigens in a sample.
Detection
In-situ hybridization detects localized DNA and RNA while immunohistochemistry detects localized proteins.
Significance
Usually, in-situ hybridization is a technique that allows for the precise localization of a specific segment of nucleic acid within a histologic section while immunohistochemistry is a powerful technique that exploits the specific binding between an antibody and antigen to detect and localize specific antigens in cells and tissue.
Method of Detection
In-situ hybridization uses nucleic acid probes for the detection of complementary nucleic acids in the sample while immunohistochemistry uses antibodies for the detection and visualization of specific proteins in the sample.
Importance
In-situ hybridization allows the detection and precise localization of a specific nucleic acid sequence within an individual cell while immunohistochemistry determines the tissue distribution of an antigen of interest in health and disease.
Conclusion
In brief, in-situ hybridization and immunohistochemistry are two techniques that detect localized cellular expression in samples such as thin tissue sections or cells mounted on slides. Generally, in-situ hybridization detects the presence of a particular piece of nucleic acids while immunohistochemistry detects the presence of a particular protein in the sample. Therefore, in-situ hybridization uses nucleic acid probes to hybridize with the nucleic acid of interest while immunohistochemistry uses antibodies to detect the presenting proteins. Hence, the main difference between in-situ hybridization and immunohistochemistry is the type of detection.
References:
- “In Situ Hybridization (ISH).” National Center for Biotechnology Information, U.S. National Library of Medicine.
- Duraiyan J, Govindarajan R, Kaliyappan K, Palanisamy M. Applications of immunohistochemistry. J Pharm Bioallied Sci. 2012 Aug;4(Suppl 2):S307-9. doi: 10.4103/0975-7406.100281. PMID: 23066277; PMCID: PMC3467869.
Image Courtesy:
- “RNA in situ hybridization in FFPE samples” By Ryan Jeffs – Own work (CC BY-SA 3.0) via Commons Wikimedia
- “Main staining patterns on immunohistochemistry” By Mikael Häggström,- Own Work (CC0) via Commons Wikimedia
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