免疫,是机体保持内在环境平衡的生理代谢功能之一,可对体外、体内或二者结合的异物或抗原发生反应,此称“免疫反应”。这些免疫反应在体内保持一定的平衡,但在某些情况下可以增强,则为有(高)反应,可称为超敏感或变态反应;也可以减弱,则为无(低)反应,可称为免疫耐受性。免疫反应的这种增强与减弱可对机体起保护、防御作用,对某些异物抗原有清除、排斥作 Immune, is the body to maintain the balance of the internal environment, one of the physiological metabolic functions, in vitro, in vivo or a combination of foreign body or antigen reaction, this is called “immune response.” These immune responses maintain a certain balance in the body, but in some cases can be enhanced, then there is a (high) reaction, which can be called hypersensitivity or allergy; can also be weakened, compared with no (low) response, For immune tolerance. This increase and decrease of the immune response may play a protective and defensive role on the body and clear and exclusion of some foreign body antigens