In the Immunohistochemistry Section, we complement the conventional histopathologic study with information obtained by techniques based on the use of antibodies in tissue specimens or cytologic samples. The antibodies specifically bind to certain cell products or microorganisms in an antigen-antibody reaction that is manifested by color signals visible on microscopic examination.
The highly specific data provided by immunohistochemical analysis are very important for the final diagnosis. Currently, these tests are used to evaluate the majority of prognostic factors in malignant tumors.
The Section is equipped with high-level technology that is continuously updated. For this reason, we are the referral center for several laboratories with more limited technological capability.
The most commonly used techniques are direct immunofluorescence and indirect immunohistochemistry, which uses polymer-antibody conjugates and reporter agents. Most of the methods are automated with robotic staining systems that apply the previously selected specific antibodies and remaining reagents on the tissue preparations.
The Section also carries out molecular diagnostic techniques, such as those based on in situ hybridization (FISH, SISH) to detect molecular abnormalities (amplifications, translocations, and deletions) and the presence of some types of viruses. Techniques based on PCR and electrophoresis are used to study mutations.
The Section routinely performs several molecular techniques to establish the diagnosis and prognosis of neoplastic disease. In breast carcinomas, in situ hybridization is used to analyze Her2 gene status as a marker of disease prognosis and response to therapy. This technique is also used to determine the presence of Epstein-Barr virus in lymphoid neoplasms, and 1p and 19q chromosomal deletions in oligodendroglial neoplasms. Furthermore, we study MGMT gene hypermethylation in gliomas, and K-RAS mutations and microsatellite instability in colorectal cancer. BRAF mutations are assessed in colorectal carcinoma and in papillary thyroid carcinoma. Evaluation of EGFR mutations was implemented in January 2011.
The Immunohistochemistry Section supports the training courses developed by the remaining Sections and plays a part in all their activities.