“…It has become clear that immunodeficiency due to genetic factors (for example, deficiency of phagocytic cells, complements, T cells, or antibodies involved in biological defense) contributes to an increase in susceptibility to infection by various pathogens [ 55 ]. However, immunodeficiency due to environmental factors (for example, pH, temperature, ultraviolet rays, a nutritional deficiency, or environmental pollutants) is thought to occur not as the result of an effect on specific immunocompetent cells, tissues, or organs, but rather as the result of an imbalance between the mechanisms that activate and suppress the immune system [ 16 , 56 , 57 , 58 , 59 , 60 , 61 ]. The immune system, therefore, contributes to the maintenance of homeostasis only when it is appropriately controlled by the interaction between immunocompetent cells, tissues, and organs.…”