What does antigen mean in human body?

(1) antigen is a substance in human body and an important component that triggers immune response. There are many kinds of antigens in human body, including autoantigens and foreign antigens. Autoantigen refers to the antigen existing in the human body's own tissues, and the principle of heteroantibody refers to the antigen carried by foreign substances such as germs, viruses and bacteria that the human body comes into contact with. After foreign antigens enter the human body, they will activate the human immune system and produce specific cellular and molecular immune responses to resist the attack of foreign antigens.

(2) Antigens mainly exist in human blood, tissues, body fluids and other organisms. The antigen in blood is related to the antigen on the surface of red blood cells, which can be detected by blood group reagents for medical purposes such as blood donation and blood transfusion. The principle of resistance in tissues is related to organ transplantation and tissue matching. The principle of humoral resistance can provide a basis for the diagnosis and prevention of diseases through immunological detection. Antigen has important application value in medical field.

(3) Recognition and response to antigen is an important function of human immune system. The response of human immune system to antigen can be divided into two types: cellular immunity and humoral immunity. Cellular immunity mainly depends on the synergistic effect of immune cells such as macrophages, T cells and natural killer cells. Humoral immunity is accomplished by antibody-secreting cells such as B cells and plasma cells. The recognition and response of antigens ensure that the human body can effectively deal with and resist foreign antigens and safeguard human health and immunity.