9 Examples of Antigens

Antigens are molecules or substances that can stimulate an immune response in the body. They are recognized by the immune system as foreign invaders, leading to the production of antibodies and the activation of immune cells.

Pathogenic Microorganisms, Parasites, Allergens, and Cancer Cells are a few examples of antigens.

Examples of Antigens

Here are some common examples of antigens:

1. Pathogenic Microorganisms

• Bacteria: Pathogenic bacteria like Streptococcus, Escherichia coli (E. coli), and Mycobacterium tuberculosis have antigens on their cell surfaces that trigger immune responses.
• Viruses: Viruses, such as the influenza virus, HIV (Human Immunodeficiency Virus), and SARS-CoV-2 (causing COVID-19), carry viral proteins that serve as antigens, provoking the immune system.

2. Fungi     

• Candida albicans: This yeast-like fungus can cause infections, and its cell wall contains antigens that elicit immune responses.

3. Parasites     

• Malaria Parasite (Plasmodium spp.): Malaria parasites have antigens on their surfaces that trigger immune reactions. These antigens are the basis for some diagnostic tests.

4. Allergens     

• Pollen: Pollen from various plants acts as an allergen, causing allergic reactions in susceptible individuals.
• Dust Mites: Dust mites and their feces contain allergenic proteins that can trigger allergies and asthma.

5. Food Antigens     

• Peanuts: Peanuts contain allergenic proteins that can provoke severe allergic reactions in some individuals.
• Shellfish: Shellfish proteins can be antigenic and cause allergic responses.

6. Transplanted Tissues     

• Organ Transplants: When a person receives an organ transplant, the recipient’s immune system may recognize the transplanted tissue as foreign antigens, leading to rejection unless immunosuppressive medications are used.

7. Blood Group Antigens     

• ABO Blood Group Antigens: ABO blood group antigens on red blood cells determine a person’s blood type. Incompatible blood transfusions can lead to immune reactions.

8. Cancer Cells     

• Tumor-Specific Antigens (TSAs): Cancer cells often produce abnormal proteins or express antigens that differ from normal cells. Immune responses against TSAs are being studied for cancer immunotherapy.

9. Autoantigens     

• Autoimmune Diseases: In autoimmune diseases like rheumatoid arthritis and systemic lupus erythematosus (SLE), the immune system mistakenly targets self-antigens, leading to tissue damage.