How Your Immune System Works

Quiz

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How Your Immune System Works

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You are exposed to billions of bacteria, viruses, parasites, and other microbes on a daily basis. To give you an idea of just how many, your hand alone has more germs living on it then there are humans alive today. Most germs you encounter are harmless, but some can make you sick.

Luckily, you have your immune system to keep the bad germs at bay.

Your Immune System

Your immune system is made up of a complex and vital network of specialized cells and organs that protect your body from infections and diseases. Behind the scenes, 24 hours a day, your immune system stays alert patrolling for intruders.

Billions of white blood cells make up the bulk of your immune system and each white blood cell has a special job. T-Cells produce specialized substances that activate other white blood cells to attack foreign invaders. B-Cells produce antibodies that fight specific infections. Macrophages and neutrophils gobble up bacteria and other invaders.

Fighting Infections

Your immune system is not simply a collection of white blood cells; specialized proteins (such as antibodies and interferon) are produced in response to infections.

  • Antibodies: Each kind of germ has an outer layer that’s different from those on other germs and a unique antibody is produced to match each of these outer layers. Antibodies your body produced to fight off last year’s flu virus can’t get a grip on this year’s model. So your immune system has to go back to the drawing board and make new antibodies. The good news is germs can’t fool your immune system twice. Once your body has withstood an attack by a specific germ, the antibody-making cells remain on alert. They’re ready to rumble if the same germs show up again.
  • Interferon: Interferon is a natural protein released by infected cells and it “interferes” with viral replication (this is how it got its name). Viruses, you may know, are unable to do anything on their own. Typically, they invade a host’s cells and then hijack that cell to produce more viruses (this is viral replication). Interferon directly blocks viruses from replicating. Overall, interferon increases the immune system’s recognition of an infection.[i] It communicates with neighboring cells (to increase their defenses) and triggers the immune system by enhancing T-cell activity, phagocytic (gobbling) activity of macrophages,[ii] and increasing the cellular destruction capability of natural killer cells.[iii]

Interferon, antibodies, and white blood cells act together as powerful allies to keep your immune system primed for when those bad germs come knocking at your door.


i Kotredes KP, Gamero AM. Interferons as inducers of apoptosis in malignant cells. J Interferon Cytokine Res. 2013 Apr;33(4):162-70. PMID: 23570382

ii Schroecksnadel K, Frick B, Winkler C, Fuchs D. Crucial role of interferon-gamma and stimulated macrophages in cardiovascular disease. Curr Vasc Pharmacol. 2006 Jul;4(3):205-13. PMID: 16842138.

iii Welsh RM. Natural killer cells and interferon. Crit Rev Immunol.1984;5(1):55-93. PMID: 6085941.

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