Antigen vs Antibody- Definition and 12 Major Differences


Antigens and antibodies are two key components of the immune system that play vital but distinct roles in protecting the body from foreign substances and pathogens. In this article, we will explore the definition and 12 major differences between antigen and antibody, as well as some examples of their types and functions.

An antigen is any substance that stimulates an immune response. Antigens may come from outside the body (foreign antigens) or from within the body (autoantigens). Foreign antigens include pathogens (such as viruses or bacteria), allergens (such as pollen or dust), toxins (such as venom or chemicals), or blood cells from another person. Autoantigens are normally produced by the body and do not trigger an immune response, unless there is an autoimmune disorder that causes the body to attack its own cells and tissues.

An antibody is a Y-shaped protein that is produced by white blood cells called B cells in response to exposure to antigens. Antibodies are highly specific, meaning that each type of antibody can only bind to one type of antigen. When an antibody binds to an antigen, it forms an antigen-antibody complex that activates other immune cells and mechanisms to eliminate the foreign substance. Antibodies also prevent antigens from infecting healthy cells by blocking their entry or neutralizing their effects.

Antigens and antibodies are involved in various types of immune reactions, such as humoral immunity, cellular immunity, allergic reactions, autoimmune diseases, blood transfusions, and vaccinations. Understanding the differences between antigen and antibody can help us appreciate how the immune system works and how it can be manipulated for medical purposes.