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The body is constantly battling against foreign agents, like bacteria, viruses and fungi, which come from the outside world and also from within the body itself.

The first lines of defense the body has for creating an immune response are the skin, stomach acid, mucosa and the cilia found along our respiratory pathways.

But if these barriers are crossed by pathogen agents, our body’s immune defenses can destroy them. There are two ways of reacting to such an attack:
Innate immune response. We count with this response since birth. The cells in charge of carrying it out are called phagocytes, and they are split into the following types: neutrophils, macrophages and dendritic cells (DC’s). Neutrophils allow blood to reach tissues once an infection or inflammation has already begun; macrophages circulate through the blood and in body tissues and attack any foreign agent that enters the body, as well as tissue waste matter. Natural killer cells (NK’s) also participate in this type of response. They attack a wide variety of tumors and cells infected by viruses. Finally, we have dendritic cells, which phagocytize antigens of pathogen agents from the inside and make them known to the immune system. This is the main point of transition between the innate immune response and the adaptive immune response.

Adaptive or acquired immune response. It is acquired after a few days go by as a consequence of the body’s exposure to pathogens and substances that are found in our surroundings. It acts against antigens that have already begun and developed an immune response. Cells known as lymphocytes participate in this process (a type of white blood cell that is responsible for immune responses). There are two types of lymphocytes: B lymphocytes (or B cells, which are born and mature in bone marrow; they produce antibodies) and T lymphocytes (or T cells, which develop in the thymus and attack cells affected by a pathogen from the inside; for example, cells affected by a virus). There are two kinds of specific immune response: cellular and humoral.