The immune system is comprised of a team of immune cells, which act according to programmed immune responses. The immune system includes leukocytes (white blood cells, including neutrophils, eosinophils, basophils, monocytes, and macrophage); and lymphocytes (T-cells, B-cells, and natural killer cells). Plasma cells (plasma B-cells, plasmocytes, or effector B-cells) make and secrete large quantities of antibodies to specific pathogens, at rates of one thousand antibodies per second. The immune cells engulf the pathogen, and attempt to digest the pathogen or carry the pathogen to the plasma cells to be killed. When the immune system cannot eradicate the pathogen the immune cells generate TNF-alpha, which is a more aggressive inflammatory response. TNF-alpha is generated primarily by macrophages, but can be generated by any immune cell; and is considered a marker of systemic inflammation. A high level of TNF-alpha is found in many chronic diseases.

The type of immortal pathogen determines the type of immune cells signaled to attack. Immune cells become infected with immortal pathogens, which can live and replicate inside immune cells, damage immune function, confuse immune signals, and spread the pathogen wherever the immune cells can reach.