Immunohistochemistry in Ophthalmology

Abstract

Immunohistochemistry is a pathological technique wherein the distribution of a particular protein or lipid antigen in a tissue specimen is determined using a combination of immunological, histochemical and biochemical principles. It is based on the specificity of antigen-antibody binding and the fact that the primary antibody, being a protein itself, can also serve as an antigen for a secondary antibody. These antibodies are then detected using fluorescent probes or enzyme labels. Techniques like enzyme digestion and antigen retrieval may be used to unmask tissue antigens and improve staining. False negatives and false positives are possible. Hence, the results must be compared with histopathological and clinical characteristics. Periodic checking of antibody activity, strict procedure protocols and appropriate positive and negative controls help decrease errors. IHC is a remarkable technique that can be applied to routinely formalin fixed tissue, to frozen sections and even to cytological preparations. It can be used to detect cell surface or even intracellular antigens. IHC is commonly used for tumour diagnosis and classification, as well as detecting prognostic markers. The use of IHC in diagnosis and characterization of ophthalmologic tumours is increasing day-by-day. It helps avoid diagnostic errors and plan appropriate management. Advancements in IHC today aim to make the method faster, simpler and more reliable with better sensitivity and specificity. Proper standardization is the need of the hour to make it more widely applicable and increase accuracy and reproducibility of the results.

Keywords

• immunohistochemistry
• primary antibody
• primary antigen
• enzyme label