PATHOLOGY

Detailed explanation-1: -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-2: -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-3: -Substances that are foreign to the host and stimulate an immune response are known as antigens.

Detailed explanation-4: -Exogenous antigens come from foreign substances that can enter your body through your nose, your mouth or cuts in your skin. These include viruses, bacteria, pollen, parasites and fungi.

Detailed explanation-5: -The main job of the innate immune system is to fight harmful substances and germs that enter the body, for instance through the skin or digestive system. The adaptive (specific) immune system makes antibodies and uses them to specifically fight certain germs that the body has previously come into contact with.