Differences between antigens and antibodies

The terms antigen and antibody are widely used when we study Immunology, that is, when we study the part of Biology related to the immune system. Knowing these two concepts is fundamental to understanding the process of defending the body against particles and foreign organisms. The following are the main differences between antigens and antibodies.


We call antigens the molecules capable of reacting with an antibody. This reaction may or may not trigger a response from our immune system. In the latter case, the antigen is known as an immunogen. As an example of antigens, we can cite viruses, bacteria and even allergy-triggering particles.


Antibodies, in turn, are glycoproteins (proteins bearing linked oligosaccharides ) known as immunoglobulins (Ig) . These very specific proteins have the ability to interact with the antigen that triggered their formation. The secretion of the antibodies is made by the plasma cells, cells that arise from the differentiation of the B lymphocyte , a cell of our immune system.

By interacting with the antigen, antibodies can provoke a series of processes aimed at protecting our body. Among the actions that the antibodies can perform, they stand out their ability to provoke the production of chemical signals that warn other defense cells about the presence of an invader, in addition to their ability to leave particles more susceptible to the process of phagocytosis.

In humans, it is possible to identify five major classes of antibodies or immunoglobulins: IgG, IgA, IgM, IgD and IgE. The most abundant type is IgG, which mainly acts by activating phagocytosis and neutralizing the antigens.

Sera and Vaccines

Knowing the concepts of antigens and antibodies, it is extremely easy to understand what sera and vaccines are . Sera can be defined as a passive and temporary immunity in which ready-made antibodies against a particular antigen are injected. In the case of vaccines, immunization is active and long-lasting, because dead or attenuated antigens are administered in order for the organism itself to produce antibodies against that agent.

In view of the definition, it is easy to see that the serum is used after contact with the antigen, since ready antibodies are injected and is therefore a form of cure. Since the vaccine is used as a form of prevention, since immunization is more durable and our own organism produces antibodies against the action of a certain antigen to which we have not yet been exposed.



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