PATHOLOGY

Detailed explanation-1: -An antigen is a foreign substance that enters your body. This can include bacteria, viruses, fungi, allergens, venom and other various toxins.

Detailed explanation-2: -These antigens stimulate a number of cells in the immune system, including macrophages, T cells, and B cells. An immune response begins when macrophages ingest antigens such as proteins entering the body and digest them into antigen fragments.

Detailed explanation-3: -Antigens are substances (usually proteins) on the surface of cells, viruses, fungi, or bacteria. Nonliving substances such as toxins, chemicals, drugs, and foreign particles (such as a splinter) can also be antigens. The immune system recognizes and destroys, or tries to destroy, substances that contain antigens.

Detailed explanation-4: -An antigen that induces an immune response-i.e., stimulates the lymphocytes to produce antibody or to attack the antigen directly-is called an immunogen.

Detailed explanation-5: -Antibodies help the body to fight microbes or the toxins (poisons) they produce. They do this by recognising substances called antigens on the surface of the microbe, or in the chemicals they produce, which mark the microbe or toxin as being foreign. The antibodies then mark these antigens for destruction.