Immunohistochemistry, more commonly referred to as IHC, helps doctors and scientists differentiate between histological subtypes of mesothelioma through the use of antigens, which help to trigger the production of antibodies from the immune system. IHC locates distinct protein antigen markers within mesothelioma tumor cells. By locating these antigens a diagnosis can be made that is more precise than one utilizing imaging scans alone. IHC is used to differentiate between it and other types of cancer, as the symptoms of mesothelioma often mimic other conditions and illnesses. Diagnosing mesothelioma in while it is still in the earlier stages can improve a patient’s prognosis.
How Does IHC Work?
Antibodies are substances that bind with antigens in all living cells. IHC uses the relationship between the two substances to identify specific cells in a sample. The first step in the IHC process is a tissue biopsy, which is then sliced into sections so that IHC can be conducted on either a slide preparation or a free-floating sample, which can be either a fresh or frozen sample. Once a sample has been prepared a lab technician will introduce specialized antibodies into the specimen through the use of a stain or florescent dye. These specimens have been labeled in such a way that they allow identification of the specific antigen proteins associated with the antibodies. Once this reaction has occurred the sample is washed and the markers remain, but only in the tagged cells, making identification possible.
This form of IHC involves the introduction of two antibodies rather than an antibody and an antigen. These two antibodies are a primary unlabeled antibody and a secondary labeled antibody. Indirect IHC is more likely to be used than direct IHC due to a higher level of sensitivity. During indirect IHC those cellular events associated with tumors, such as cell death, become highlighted on the stained tissue sample. These cellular events then help the pathologist or other diagnostician determine the histology of the tumor based on a variety of cellular activity.
There are two commonly used protein markers for the diagnosis of mesothelioma histological subtypes. Those protein markers are BerEP4 and vimentin. While BerEP4 has yet to be proven in diagnosing mesothelioma directly, it does distinguish between mesothelioma and other forms of cancer, helping doctors and oncologists rule out other forms of disease. Vimentin is a filament protein located within microvilli. As is the case with BerEP4, vimentin is useful in differentiating malignant mesothelioma from adenocarcinomas, but it has yet to be proven in distinguishing malignant from benign hyperplastic mesothelial cells reliably. IHC remains among several methods being researched to help aid medical science discover better diagnostic processes and treatment methods.