Our body has a complex defense system against external and internal aggressions called the immune system. Made up of cells, organs and tissues perfectly intercommunicated and coordinated with each other, which create an effective system to fight against viruses, fungi or bacteria and prevent possible infections. The immune system has different mechanisms to achieve its objective: A system of physical barriers, whose main function is to prevent harmful agents from entering the body, consisting of the skin and mucous membranes together with saliva, tears, mucus … And an active response to the aggressor once it has penetrated our body. This answer can be:
- Quick, general and unspecific, treating all aggressors in the same way. It’s about innate immunity. He has no memory of the encounters. The cells involved are: monocytes, macrophages, neutrophils, eosinophils, a type of lymphocyte called NK cells (“Natural Killer”) …
- Acquired or specific immunity is a more complex and efficient system with the capacity to learn, adapt and remember: it comes into contact with microorganisms and recognizes molecules on their surface, antigens; He memorizes them and remembers them for the next time he comes into contact with them, attacking them in a targeted and specific way. The cells responsible are B and T lymphocytes.
- B lymphocytes are cells specialized in the production of antibodies or immunoglobulins (Ig): receptors on their membrane that recognize the invader’s antigen. The Ig that are created when coming into contact with the antigen are the Ig M and are the first that can be detected, indicating that it is an acute infection. While Ig G are souvenir antibodies and provide more long-term protection.
- T lymphocytes are cells programmed to recognize antigens, respond to them, and remember them.