OLIVE OILS AND HEALTH 182 15.1. The immune system. A short description The immune system, or immunity, can be defined as a network of mechanisms which first recognise and later destroy “strange” agents endangering our health. These agents include not only infectious microorganisms (parasites, bacteria, and viruses), but also molecules and particles capable of triggering an allergic reaction, and even our own cells during a cancer process. The immune system mechanisms fall into two categories: - Adaptative, or specific, immunity which appears a few days after the entry of a strange agent in the body, and it is specific against it. One of the mechanisms involved is an antibody generation by B lymphocytes. Antibodies bind the agents and neutralize them. In many cases the diagnosis of an infection is linked to the identification of the produced antibodies rather than the infectious agent itself. This method is used to identify asymptomatic individuals who have been in contact with type 2 coronavirus, responsible for the severe acute respiratory syndrome (SARS CoV 2) also typified as coronavirus 19 (CoViD-19) disease. After the arrival of the infectious agent the T lymphocyte blood cells are activated, and they then destroy the body cells which have been invaded by the pathogen agent. T lymphocytes also collaborate with other immune cells to provide a proper immune response. An uncontrolled response can be life threatening. - Innate, or non-specific, immunity which acts immediately after agent entry. It responds in the same way to all germs and foreign substances. A key mechanism of the innate immunity against infections is the inflammatory response. The two types of immunity frequently interact with each other. Molecules produced by one modulate mechanisms belonging to the other. 15.2. Inflammation Inflammation, or inflammatory response, is one of the main innate immunity mechanisms. In a similar manner to all the mechanisms involved in this type of response, inflammation is immediately triggered after agent entry. There is a local vasodilation with an increase in blood flow which favours the arrival of immune response cells to the injured site. These cells, in turn, generate molecules which recruit and activate immune cells from other parts of the body also conveying them to the infection site. All these cells produce pro-inflammatory molecules which trigger a powerful inflammatory response to destroy the infectious
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