Antigenicity tumors

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Following the AFP was detected and other cancer-embryonic antigen detection, which with the help of highly sensitive radioimmunological method is widely used in clinical Oncology. In normal conditions this antigen characteristic of embryonic cells, and adults may be present in trace quantities. Its concentration increases in cancer and less sharply in inflammatory diseases of the internal organs. Believe that carcinogenesis associated with reactivation of the gene encoding this protein synthesis, however, as some other embrio-specific products.
The herd-specific or differentsirovaniya antigens are derived consistently switches on genes. Protein molecules intermediate steps required for the implementation of different variants of intercellular interactions, which ultimately leads to the appearance of different variants of histological structure of the original tissue. The tumor cells temporary biochemical products are constant, reflecting the high activity of some deviant gene that continue to operate in an unnatural mode. Monoclonal antibodies targeted against a number differentsirovaniya antigens was the case reagents for the detection of many types of cancer.
In recent years intensively investigated the relationship between tissue antigens compatibility and tumor characteristics. Partly this has already been discussed above. The risk of cancer increases with the state of homozygosity, when the alleles of a single gene on the paired chromosomes are the same, and polymorphism is reduced. First of all it concerns the most diverse composition of the class I antigens.
The class I antigens, as already mentioned, are present in all mammals, it is their first recognize cytotoxic T-lymphocytes. People have discovered more than 100 allelic genes of this series is able to provide many billions of different combinations, each of which is inherent only to one person. Among proteins tissue compatibility they first appear on the cells of the embryo and placenta, and their lack of expression causes many deviations from the physiological course of pregnancy up to the immunological spontaneous abortion.
In experiments on animals, it was noted that the decrease in the expression of antigens I class correlates with carcinogenesis, in particular caused by viruses. Some viruses, apparently, have the electoral orientation (trapnest) to the class I antigens, they are embedded in the cell membrane namely in the areas of receptors these antigens. Viruses can block, to mask the class I antigens, and in this case, the cytotoxic T cells cease to have a biocidal effect (tumor markers are recognized by the immune system in a complex with its own antigens class I), Sarcoma of mice caused by chemical carcinogens type methylcholanthrene, find a deficit of class 1 antigens. They are bad object for immunological elimination. Reduced the composition of the class I antigens was also observed in the cells of virus-induced leukemia and spontaneous lymphomas mice, small cell lung cancer man. These tumor cells have the ability to spread faster in the body, to give distant metastases.
In some other cases, such as tumors of animals caused by a virus polyamy, the composition of the class I antigens increased due to their enhanced transcription. Not clear what mechanism when this leads to the avoidance of cell tumors immunological surveillance; most likely comes into virus-induced immunosuppression.