Department of Pathology & Laboratory Medicine
Laboratory of Immunohistochemistry and Molecular Pathology
Dr. Sue Heffelfinger is the Director. This laboratory offers traditional histopathology and histochemistry, immunohistochemistry and molecular pathology services.What is immunohistochemistry?
Immunohistochemistry is the branch of immunology concerned with clinical reactions to the immune system. It is the specific study of antigens and antibodies and their reactions with one another. The immunohistochemical technique can be used on paraffin embedded tissue, fresh frozen tissue and tissue embedded in plastics.Background of immunohistochemistry?
Today, the diagnosis of a great number of diseases depends upon the microscopic examination of a cell or tissue preparation by a pathologist. With experience, a pathologist may deduce from the patterns observed (morphology) whether or not abnormalities are present in the tissue. This method is uncertain, however, for often cells cannot be positively identified from their appearance alone, and their functional state is even more difficult to evaluate on this basis.Immunologic methods, including immunoperoxidase tissue stains, permit a more certain knowledge of cell identity and function. The chemical principle which supports these methods is derived from a phenomenon of the immune system of vertebrate animals, the production of antibodies.
Basics of immunoperoxidase staining
There are two main goals in the immunoperoxidase technique. The first is to seek out and identify a specific antigen in tissue. This is accomplished by developing an antibody with high affinity for the antigen in question and then incubating it with the tissue where it will bind chemically to that antigen. The second major goal is to make the antibody-antigen complex visible. This is accomplished by marking the site with dye molecules which are discernible under a standard light microscope.Advantages of immunoperoxidase staining
- The stain permits the pathologist to simultaneously evaluate the morphology (structure) of a cell or tissue section using traditional criteria. The possibility of diagnosing a difficult case is greatly enhanced when knowledge of specific antigen sites is added to the morphological information. Since immunoperoxidase is supportive of and does not dispel the traditional criteria, the method is easily accepted by the clinical community.
- The antigen-antibody complex can be visualized within minutes by using an ordinary light microscope.
- Immunoperoxidase staining can be performed on tissues that have been routinely preserved (fixed) and stored (paraffin embedded) by hospital laboratories. This allows the pathologist to do retrospective studies as well as current evaluations.
- The labeling (staining) of antigen sites is permanent and the cell or tissue sections can be stored for future evaluations.
- The immunoperoxidase method permits investigators to study functional aspects of many tumors. For example, does the distribution of cellular components change during malignant (cancerous) transformation? Studies like these can result in a better understanding of normal and abnormal cell types.
Molecular Pathology
The Laboratory has developed protocols for in situ hybridization (ISH) to detect sequence-specific RNA or DNA in fixed human tissue using oligonucleotide, DNA and RNA probes. Both enzymatic and isotopic labeling techniques are used. Protocols for fluorescent ISH using alpha-satellite and bacteriophage probes have been perfected for genomic analysis and include dual and triple labeling interpreted by three-dimensional scanning and confocal microscopy. The lab is accredited by the College of American Pathologists for clinical laboratory tests to support diagnosis of Epstein Barr virus mRNA, cytomegalovirus, BK and JC virus (causative agent for progressive multifocal leucoencephalopathy), herpes simplex virus, parvovirus B-19, and adenovirus.
[ The Web at UC | UC Home ]