With the entry of the Antigen (Ag), the defensive system, is activated macrophages recognize the AG as strange and engulf it (SUVs), triggering a series of reactions within the macrophage to delete it, at the same time these macrophages displayed on its surface protein parts of the Ag, facilitating other macrophages recognize Antigen and go to the site of infection to continue attacking, but also T cells (aided) alert you to identify to the Ag to lymphocytes T lymphocytes B and destroyers out to attack,(los primeros anticuerpos que producen los linfocitos B son las inmunoglobulinas M y luego las inmunoglobulinas G), also these immunoglobulins are specific for each Ag (viruses, bacteria, fungi, etc.) and are them who recognize the AG immediately when they enter these Ag again in the body, making this immune reaction much more quickly than the first (immunological memory). Phagocytes when they arrive at the site of infection, eat the invading micro-organism. The ingestion of micro-organisms is much easier as covered of antibodies, complement, or both. Once the phagocyte is eaten to the micro-organism, it initiates a series of chemical reactions inside the cell, resulting in the death of the micro-organism. Once controlled the process (allergy, infection, etc.), suppressor T cells send the signal to the macrophages, B lymphocytes, lymphocytes T help and destroyers to curb the immune response. Among the functions of the immune system is recognize your same body as their own cells, which begins very early (during fetal development), the immune system distinguishes own cells (immune tolerance), for it destroys T lymphocytes that recognize as a stranger to own cells. When this doesn’t work can appear the autoimmune diseases. Autoimmune diseases occur when the body does not recognize as their own some of the cells that form it and create antibodies against them, attacking so to their own cells.