How do white blood cells know what to kill? How do white blood cells know to kill bacteria cells and not human cells. How do they differentiate between the two?
The body recognizes chemical structures that are made by bacteria and quite different from chemicals made by higher organisms. These chemical structures include the special carbohydrates (sugars) and lipids that surround bacteria and peptides, such as the amino acid formyl methionine, which bacteria put at the beginning of all of their proteins.
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