The immune system is like an invisible shield that protects our body and allows us not to get sick by keeping the body's natural defenses high. Since our body is exposed to various pathogens such as bacteria, viruses, fungi or parasites on a daily basis, our immune system works around the clock to protect our body from infections and diseases. The immune system implements two forms of defense: non-specific or innate immunity and specific or adaptive immunity.

Innate immunity refers to first defense mechanisms against microbial invasion. It consists, first of all, of epithelial barriers of the skin and mucous membranes. When the pathogen enters the body, it is attacked by phagocytes or natural killer lymphocytes. Innate immunity also has the task of enhancing the adaptive immunity response.

Adaptive immunity refers to a more specific defense strategy against pathogens or antigens of various kinds. It develops slower than innate immunity as it requires lymphocyte differentiation before it can provide adequate defense. Adaptive immunity is the work of lymphocytes and their products, antibodies. Adaptive immunity can be of two types:

  • Humoral adaptive immunity, by the antibody-producing B lymphocytes
  • Cell-mediated adaptive immunity by T lymphocytes

The humoral immune response is especially important in the defense against bacterial infections; instead the cell-mediated one is effective especially against parasites, viruses, fungi, tumors 

Lymphocytes represent the main component of adaptive immunity. Their receptors only recognize protein microbial antigens. Cell-mediated immunity is specific against intracellular pathogens and, in fact, T lymphocytes kill any cell into which infectious agents have entered. B lymphocytes are the only cells capable of producing antibodies. The antibody proteins are then expressed on the B lymphocyte membrane acting as antigen receptors. Then the antigen is recognized by antibodies located on the B lymphocyte membrane and captured. Antibodies can recognize different types of molecules such as proteins or lipids.

While B lymphocytes are activated not only by cells but also by pure circulating antigens, T lymphocytes need direct contact with a cell that presents the antigen to be activated. Therefore if the T cell encounters a pure antigen it produces no response. For its activation, the T lymphocyte must recognize the antigen already bound to the MHC proteins.

When the attack is massive and our immune system does not immediately recognize the enemy pathogen, we feel a series of symptoms that indicate that our body is fighting the infection. Fever caused by the flu virus is the classic example.

In order for the immune system to function properly, it needs to be strengthened throughout the year.

The earlier we take care of our immune system, the lower the risk of getting a cold or flu infection. The strength or vulnerability of our immune systems to disease and infection depends on several factors.

How can I strengthen my immune system? Reduce stress, exercise regularly in the fresh air, get enough sleep, eat properly, hydrate, do not smoke.

Dr. Milan expert in Nutrition. Graduated in Biology and Biomedical Applications at the University of Parma, he shows us how to defend ourselves in a natural way from typical seasonal ailments. Click here to read more.

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