Cytokines, immunoglobulins, T lymphocytes, vaccines, monoclonal antibodies.
Our vocabulary in recent times has been enriched with a series of terms, which hide complex concepts, inherent in the field of the immune system, the guardian angel within us who protects us every day from a series of attacks. In silence. But how does this complex and effective machine work, capable of eradicating millions of germs and cancer cells, helping to maintain our state of health? From a structural point of view, the immune system is composed of hundreds of small organs (i lymph nodes), by two large organs (spleen and thymus) and by the bone marrow, all connected to each other by a very dense network of lymphatic vessels. “Stations” of immune cells are also present within a range of organs and tissues (lungs, intestines, liver, brain, joints, tonsils and adenoids).
THE CHEMICAL SIGNALS
All these cell they talk to each other through chemical signals, represented by cytokines (5 main types: chemokines, interferons, interleukins, lymphokines and TNF), small proteins that influence the immune response in various ways. Every day, the system produces billions of new cells that travel around the body through this complex network. An army complete with simple soldiers, commanders, kamikaze cells, “smart” missiles and time bombs. A peaceful army, until activated by a substance that the body recognizes as foreign (an antigen). There are two subtypes of immunity: the innate one (mainly managed by neutrophils and macrophages) and the adaptive one (specific or acquired, operated by T and B lymphocytes). Innate immunity offers a quick but generic response against germs or harmful substances that enter the body. The adaptive one produces antibodies, weapons custom built to target a particular enemy. The two systems work together, in sequence.
THE FIRST ANSWER
When we injure ourselves with an infected object, bring food to the mouth with unwashed hands or are overwhelmed by a cough or sneeze from a person, thousands of germs find a gateway into our organism and begin to attack. our cells. These, before succumbing, send alarm signals, real chemical screams, which attract the attention of the sentinels of the immune system. Macrophages immediately rush to the site, large cells that attack germs and destroy them, literally eating them (each macrophage can eat at least hundreds of battery). But if the number of invaders is too high, the macrophages in turn ask for reinforcements. Help comes to them from neutrophils (white blood cells circulating in the blood), merciless kamikaze cells, which release chemicals that are deadly to invaders, or devour them directly. The site of the battle, especially if visible from the outside (a wound, a graze, sore throat and tonsils) appears red, hot, painful and sometimes even swollen. These are the signs of inflammation, that is, of the battle that the cells of the immune system are fighting without holds barred. Meanwhile, the blood vessels surrounding the area become more permeable and send a chemical paraphernalia made up of complement proteins to the battlefield, which in turn bind to bacteria or viruses, tear them apart and sound the alarm for attract additional reinforcements to the scene. Sometimes the battle ends here.
THE HIGHER LEVEL
Other times, however, to destroy the invaders, the immune system is forced to implement a superior defense plan (adaptive immunity). The protagonists of this phase are the so-called dendritic cells, a sort of secret agents of the immune system which, while the “soldiers” are busy fighting, analyze the structure of the invaders and collect fragments (antigens) to be analyzed to build the line of subsequent, more targeted defense. These cells carry the material to the immune system’s checkpoints, the lymph nodes. Here they present the antigens to the helper T cells, until they find the one that can recognize that particular fragment. Selecting the specialized T helper against that germ, they activate it and multiply it to create a small army capable of fighting aliens. A part of these T lymphocytes goes to the battlefield to support macrophages; meanwhile the others go by B lymphocytes, the cells that make antibodies, to make them produce smart missiles against those germs. The antibodies surround and harm the bacteria, while the soldiers of the immune system (macrophages and T lymphocytes) attack and eliminate them permanently. Once the war is won, some T lymphocytes are transformed into “memory cells”, ready to intervene.
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