Suppression of the immune response in cancer

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If under normal conditions, the immune response ends immunosuppression when cancer he begins with it. Cancer "confuses" immunity, makes him "miss", "do not hit the target".
There are several theories suppressor effect of malignant tumors in the body.
1. To avoid immunological destruction, the ancestor of the tumor, or cancer stem cell, must suppress the cytotoxic function EC-cells and macrophages. Otherwise, the tumor does not state ISA. The oncogenes as viruses, chemicals, physical factors. The essence of their action is not only to mutagenesis, mutations occur frequently (estimate that up to 105 cells of the human body every day mutate), but also to change the order "on" regulatory genes. Oncogenesis, apparently, is connected with the fact that the new gene (oncogene) encodes a protein, soluble suppressor factor instead of another physiological product (for example, growth factor).
Such a mechanism is shown recently, with the syndrome of acquired immune deficiency when the virus of T-cell leukemia person of the third type (HTLУ-W) is embedded in the chromosome of T-helper and causes these cells to develop not interleukin, and soluble protein that blocks the immune system. The consequence of this is the development of tumors and the defeat of the body usually non-pathogenic microbes.
In tumor growth in the serum at the very early stages of the disease are detected blocking factors that inhibit the reaction of cellular immunity in all existing laboratory tests. The presence of the blocking factors indicates a malignant tumor, and their concentration is an adverse prognostic factor. These blocking substance serum can be products of the tumor itself, T-helpers or occurring in cancer suppressive cells.
2. Because activation of the EC-cells is not achieved in the absence of interferon and interleukin-2, the development of such situation, when the products tumor competitive blocking the receptors, the EC-cells and T-killers, resulting in their "blindness". In particular, in cancer patients, there is insufficient production of interferon and IL-2, and their synthesis can be weakened because of violation of the positive feedback, as macrophages and T-helpers do not receive the message of the need to develop these products.
3. Known ability of embryonic tissues to enhance the activity of lymphocytes-suppressors. This largely explains the local accumulation supressornah cells in the lymph nodes draining pregnant-ing the uterus, and in decidual layer of the uterus, participating in the creation of the parent part of the placenta. There are and the EC-like cells that do not harm the fetus, and inhibit immunological reactivity maternal lymphocytes.
The ability of embryonic tissues to stimulate suppressor mechanisms is illustrated by the fact that transplanting them (brephoplasty) accompanied by longer survival of transplants than from adult donors.
Between embryonic and cancer cells have a lot in common. Cell tumors contain fetal proteins (e.g. cancer-embryonic antigen), synthesize embryonic products (alpha-fetoprotein and others) and interact with serum against
embryonic antigens (monoclonal antibody). Not surprisingly, if you find that "embryolisse" promotes biological suppression of the immune system in cancer. With a variety of malignant tumors marked synthesis of human chorionic gonadotropin, a hormone of pregnancy with immunosuppressive effect.
Suppressor lymphocytes appear in the blood of experimental animals within a day after tumor transplantation. Over the same term in the blood of women appears soluble suppressor factor produced by the fertilized egg (early pregnancy). Suppressor lymphocytes are found in the lymph nodes, regional to the place of syngeneic transplant tumors, they are in paraaortal lymph glands during pregnancy. Later, these cells are found in the spleen and thymus, as in cancer, and during pregnancy.
Lymphocytes-suppressor circulate in the blood during the whole time of tumor growth. They disappear after 5 hours after surgical removal of the tumor, but again appear in the bloodstream when relapse. Our studies have shown that cells, suppressor infiltrate the tumor tissue, and the stronger the admixture of such cells, zlokacestvennoe flows tumor disease.