Macrophages against cancer

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Any distinction between the individual components of the immune system, protects against the development of tumors, of course, relative. But this is helpful for understanding the state of being of a complex process. We have already mentioned that even cytotoxic antibodies can destroy the cells not independently, but together about a complement, the source of which are the same macrophages.
The complement system is presented with several proteins. With the help of enzymes they include each other in the so-called "the complement cascade", whose ultimate goal is the breakdown of protein molecules, marked by antibodies. The most important role in cytolysis complement play a special enzymes, called serine proteases, they sever the amino acid chain in the places of localization of serine. It should be noted that all cytotoxic cells-lymphocytes and macrophages have similar enzymes. Apparently, the pathogenic mechanism of action different immunological weapons in something similar.
In experiments on mice have shown that antibodies against the same tumor antigens (even when they belong to the same class IgG2) have different effects on tumor cells: antibodies type IgG2a kill them, and IgG2b promote tumor growth. The introduction of exogenous IgG2а antibodies accelerates the process of rejection of the tumor, but it happens with the active participation of macrophages. While antibodies accelerate the activation of macrophages, which penetrate into the tumor stroma and release there cell poisons. It is noteworthy that intratumoral macrophages have sensitive receptors not to transplantation antigens normal cells and tumor antigens.
Macrophages isolated from human cancers, under the influence of mouse monoclonal antibodies also be capable murderers of cancer cells. He Koprowski from the Institute of biology and anatomy in Philadelphia, thinks that antibodies type IgG2a, voorwaa macrophages can in the future be used in the immunotherapy of human cancers.
Activation of cytotoxic macrophages can also be achieved by the introduction of products of bacterial Origin, what is the basis for a long empirical Observation resorption of tumors in patients who have infectious diseases. When inflammation is triggered migration of macrophages (chemotaxis), and their phagocytic activity, the ability to products nonspecific protective factors. The presence of a tumor in the body causes sensitisation, and therefore even nonspecific increased activity of macrophages informs them of specific anti-tumor properties. On the contrary, during the suppression of the functions of the system macrophages (this purpose in the experiment used the quartz powder, dextran sulfate, carragenan and other substances) tumors easier perebivaetsya and grow faster.
The study of such stimulants macrophages, as BCG, preparations of gram-negative bacteria and corynebacteria, showed that serum immunized animals appears factor causing when it is introduced into the tumor hemorrhage necrosis. In 1975 by a group of authors, headed by L. old (USA), was described by the tumor necrosis factor (TNF), which is present even in the serum of healthy subjects. The maximum concentration in the blood combined with the introduction of BCG and lipopolysaccharides, TNF consists of two components: the cytotoxic and necrotic. To its products, in addition to the necessary microbial stimulus has some attitude and liver immunized of the body, although the source of TNF are macrophages.
If macrophages produce TNF, its destination and stimulant is a tumor, as bacteria and fungi immune to TNF. However, not all tumors sensitive to it in equal measure. TNF actively interacts with tumors located under the skin. Perhaps this is due to the presence of receptors to name some normal cells, particularly fat. TNF strengthens them metabolism products of glycerin or, say, mobilizes energy resources tissues. When intense production of TNF (and in special circumstances it can develop themselves tumor) is exhaustion of the body, cachexia. So the name is sometimes called kahectina.