Difference Between Allergen and Antigen

Allergen vs Antigen
 

Allergen and antigen are both foreign substances that can cause certain disorders to animals, but there is some difference between them in terms of their nature and the diseases caused by them. Both these substances, allergen and antigen, are directly associated with the immune system and its functions. Through this article let us explore the differences that prevail between allergen and antigen, while understanding the nature of these two substances.

What is an Allergen?

An allergen is a nonparasitic foreign substance that can cause certain immune reactions in the body when it enters the body. The condition caused by allergens are called allergy. Allergy can cause some disorders in the mucosa, skin, gastrointestinal tract, airways, and vessels resulting in symptoms like urticaria, dermatitis, edema, asthma, etc. The most common allergens are the dust, pollen, pet dander, or certain chemical substances in food or water.

Most of the food allergens contain glycoproteins, which dissolve in water and are resistant to digestion. Because of this reason, these glycoproteins are recognized as specific antigens in the body by the immune system, resulting in Type I and Type IV allergies. The severity of allergic reactions can vary from person to person (genetic susceptibility). In addition, allergies are also determined by the properties of the allergen and environmental aspects.

Difference Between Allergen and Antigen

Edema of Right Hand Due to Allergic Reaction

What is an Antigen?

The antigen is a foreign substance that can trigger the immune system to produce a specific immune response. This immune response leads to produce antibodies that can neutralize or destroy the foreign substances that entered the body. Each antibody is antigen specific and has a unique molecular structure. Proteins and glycoproteins are the most effective chemical antigens produced in the body. Other than that, bacteria and other parasitic substances are also considered as antigens.

There are three types of antigens; exogenous, endogenous and autoantigens. Exogenous antigen is an antigen that enters the body via inhalation and ingestion. Endogenous antigen is an antigen that is produced within the body due to an infection. Autoantigen is a protein that is recognized and attached by the immune system only due to genetic and environmental factors. The diseases human get due to autoantigens are called autoimmune diseases. Some common examples for autoimmune disease include Addison’s disease, Celiac disease, Graves’ disease, multiple sclerosis, reactive arthritis, etc.

Allergen vs Antigen

Antigen presentation

What is the difference between Allergen and Antigen?

• Definition:

• An allergen is a nonparasitic foreign substance that can cause certain immune reactions in the body when it enters the body.

• Antigen is a foreign substance that can trigger immune system to produce a specific immune response by the production of antibodies.

• Nature and Examples:

• Allergens are non-parasitic agents like dust, pollen, pet dander or certain chemical substance in food or water.

• Antigens can be either chemical substances (proteins, glycoproteins, etc.) or pathogens (bacteria and viruses).

• Treatments:

• Treatment for allergen is not very complex.

• Treatment for antigen is more complex than treatment for allergen.

• Disorders/ diseases:

• Allergen can lead to certain disorders like itchiness, urticaria, dermatitis, edema, asthma, etc.

• Antigen can lead to bacterial and viral diseases, autoimmune diseases, etc.

 

Images Courtesy:

  1. Edema by CFCF (CC BY 3.0)
  2. Antigen presentation by user:Sjef (CC BY-SA 3.0)