An antibody

An antibody is a protein produced by lymphocytes of the immune system in response to the presence of a foreign antigen in the system. It usually binds to the foreign antigen and causes it to precipitate from the circulation (Ross, Romrell and Kaye 7). Antibodies can be purified in the laboratory and conjugated (chemically bonded) to a variety of substances, including a fluorescent dye such as fluorescein. This conjugated antibody can then be applied to sections of tissue that have been lightly fixed or frozen so that the location of the antigen in the tissue being examined can be visualized using a fluorescence microscope. This is known as immunohistochemistry or immunocytochemistry.

The antibodies are produced by isolating a protein from one species, such as a rat, and injecting it into another species, such as a rabbit. The protein will then stimulate the rabbit to make antibodies against it, which can then be harvested from the rabbit's blood where they circulate, conjugated to fluorescent dyes, and then used to localize that particular rat antigen in tissues suspected of containing it. If the antigen is present, the antibody part of the conjugate would bind to it and could then be visualized under the fluorescent microscope because of the fluorescent dye it contains (7-8). The antibodies can also be conjugated to gold or ferritin so that they can be used to stain tissues to be examined under the electron microscope.

Enzyme histochemistry can be combined with

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meal size. This is an example of immunohistochemistry being used to visualize neurochemically specific pathways in the mammalian brain. Messenger RNA levels of OLIG1 and OLIG2 transcription factors are elevated in oligodendrogliomas (Azzarelli, Miravalle and Vidal 170-179). These researchers raised polyclonal antibodies to a synthetic peptide homologous with the transcription factor OLIG1 and studied the expression of OLIG1 in 84 brain tumors and in non-neoplastic brain tissue using immunohistochemistry techniques. They found moderate to strong intranuclear immunoreactivity in all oligodendrogliomas, oligoastrocytomas, and dysembryoplastic neuroepithelial tumors in cells identified as oligodendrocytes. Some astrocytomas also showed slight to moderate intranuclear immunoreactivity. Double immunostaining of oligodendrogliomas, oligoastrocytomas, and glioblastoma multiforme using antibodies to OLIG1 and GFAP showed cells immunopositive for OLIG1 only; cells immunopositive for GFAP only; and cells immunopositive for both antibodies. This showed that immunohistochemistry can be used to localize oligodendrocyte transcription factor in brain tissue. Intralaminar thalamic nuclei are a major site of non-dopaminergic degeneration

Category: Medical - A