Saturday, August 20, 2022


There are 3 types of exotoxins: cytotoxins, neurotoxins, and enterotoxins. A cytotoxin has a direct toxic or destructive effect on certain cells of the body. Cytotoxins kill the host cell or disrupt its normal functions.

Cytotoxins are the chemical weapons that Killer T-cells use to destroy infected cells. Viruses take over healthy cells and trick them into making many more viruses. When those viruses get out, they can infect even more healthy cells. By killing infected cells before these viruses get out, cytotoxins protect body healthy cells. Many cancer treatments use cytotoxins to kill cancer cells. Cancer cells, by definition, rapidly divide compared to the normal cells in your body.

Different kinds of cytotoxins work in different ways. Some cytotoxins make holes in the cell membrane, so the inside of the cell is not protected from the outside.

Polypeptides cytotoxins also cause structural cellular damage and an inflammatory response by a variety of mechanisms, such as blocking protein synthesis or hampering the formation of energy-rich intermediates, and interference with the normal assembly and turnover of the cell junctions and the cytoskeleton.

Examples of organisms that produce cytotoxins include Clostridioides difficile, some EPEC, enterohemorrhagic E. coli (EHEC), and Shigella. Pathogenic strains of C. difficile produce 2 structurally similar protein exotoxins, namely, toxin A and toxin B, which are the major known virulence factors.

Bacterial cytotoxins, which are produced by Shigella dysenteriae and certain E. coli serotypes, have been related to hemolytic uremic syndrome and thrombotic thrombocytopenic purpura, probably by initial insult to vascular endothelial cells.

Characteristics of the cytotoxic activity, including its heat lability, inhibition by certain drugs, precipitation with (NH4)2SO4, molecular size, and polydisperse chromatographic pattern, are similar regardless of the lymphocyte source.

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