Table of ContentsView AllTable of ContentsThe Immune SystemHow It WorksTypesRole of AntigensRole of AntibodiesSignificanceTesting Relevance
Table of ContentsView All
View All
Table of Contents
The Immune System
How It Works
Types
Role of Antigens
Role of Antibodies
Significance
Testing Relevance
Learn more about antigens and howthe immune systeminteracts with them to protect you.
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The human body relies on certain defenses to help keep sickness at bay. The immune system triggers a response that produces cells and proteins to fight off infections.
There are two types of immunity at work within the body—innate and acquired.
Types of Immunity
The body needs to be able to recognize what belongs and what doesn’t, and antigens are an important part of that process.When the body identifies an antigen, it will initiate an immune response.
When receptors on white blood cells bind to antigens, this triggers the immune response.
Antigens can be grouped in different ways.
Foreign Antigens
This type comes from outside of the body. They may be called exogenous antigens or heteroantigens. These can be from bacteria, viruses, fungi, parasites, pollen, snake venom, and certain food proteins.
Autoantigens
Endogenous Antigens
Your body’s cells display several types of antigens. Antigens on red blood cells determine blood type.
The Role of Antigens
Lymphocytes include B cells and T cells. B cells make antibodies that can bind to specific antigens. After an antigen gets bound to a B cell receptor, antibodies are produced.
T cells have antigen receptors on their cell membrane that only bind to antigens displayed on the surface of other body cells. This can occur after a virus or other foreign invader enters a cell and a fragment of it is moved to the surface to be displayed as an antigen.Different types of T cells may then destroy the infected cell or trigger other cells to respond to the antigen.
Vaccines
A vaccination is a medical injection or pill that contains a protein or weakened or dead version of a pathogen. Vaccines are used to create an immune response within the body against a particular antigen.
Once you are vaccinated, your antibodies should remain ready to fight the infection for years.
How Vaccines Work
Viral Infection
The antigens on the infectious virus signal an immune response, causing the body to create antibodies for the specific strain of viral infection. These antibodies then utilize what is known as immunological memory to help you fight the infection if you are exposed again.
Immunological memory means that once your body has encountered an antigen previously and produced antibodies to it, some long-term cells retain that memory and can produce antibodies to it quickly on the next encounter.
The Role of Antibodies
Neutralizing antibodies bind to antigens and prevent them from affecting cells, such as binding to a viral antigen in a way that blocks it from entering a cell.Non-neutralizing antibodies bind to antigens and can signal immune system cells to produce a variety of responses.
Antigens are an important part of the immune response because they help your body recognize harmful threats to get rid of them.
Tests for antigens and antibodies can be done with blood samples. These tests can help diagnose illnesses, prevent immune reactions, or check to see whether you have responded to a vaccine.
Antigen Test
Antigen tests are used to diagnose illnesses that are currently present in the body. For example, in terms of COVID-19, antigen tests can determine whether or not the virus is present in the person.
Antibody Test
As opposed to COVID-19 antigen testing, antibody testing can be done after the infection resolves. In developing a vaccine, researchers will look to see whether a vaccinated person developed antibodies.
Blood and Tissue Antigen Testing
Testing for different blood or tissue antigens is a very important aspect of blood transfusion or tissue or organ transplant.
In the case of blood transfusion, blood types must have compatible antigens between donor and recipient. If the blood donor’s and recipient’s antigens are incompatible, the recipient’s antibodies can immediately attack the incompatible donated red blood cells. The resulting transfusion reaction can be fatal.
Similarly, tissue typing such as forhuman leukocyte antigen (HLA)is commonly done before organ or tissue transplant to prevent organ or tissue rejection.
A Word From Verywell
Antigens are key players in body immunity and play a crucial role in the prevention and elimination of diseases.
8 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.InformedHealth.org Institute for Quality and Efficiency in Health Care (IQWiG).How does the immune system work?Eiz-Vesper B, Schmetzer HM.Antigen-presenting cells: potential of proven and new players in immune therapies.Transfus Med Hemother. 2020;47(6):429-431. doi:10.1159/000512729LibreTexts.11.3B: Antigen-presenting cells - B and T cells.Auladell M, Jia X, Hensen L, et al.Recalling the future: Immunological memory toward unpredictable influenza viruses.Front Immunol. 2019;10:1400. doi:10.3389/fimmu.2019.01400Sedova ES, Scherbinin DN, Lysenko AA, Alekseeva SV, Artemova EA, Shmarov MM.Non-neutralizing antibodies directed at conservative influenza antigens.Acta Naturae. 2019;11(4):22-32. doi:10.32607/20758251-2019-11-4-22-32Scohy A, Anantharajah A, Bodéus M, Kabamba-Mukadi B, Verroken A, Rodriguez-Villalobos H.Low performance of rapid antigen detection test as frontline testing for COVID-19 diagnosis.J Clin Virol. 2020;129:104455. doi:10.1016/j.jcv.2020.104455Jackson LA, Anderson EJ, Rouphael NG, Roberts PC, Makhene M, Coler RN, McCullough MP, Chappell JD, Denison MR, Stevens LJ, Pruijssers AJ, McDermott A, Flach B, Doria-Rose NA, Corbett KS, Morabito KM, O’Dell S, Schmidt SD, Swanson PA 2nd, Padilla M, Mascola JR, Neuzil KM, Bennett H, Sun W, Peters E, Makowski M, Albert J, Cross K, Buchanan W, Pikaart-Tautges R, Ledgerwood JE, Graham BS, Beigel JH; mRNA-1273 Study Group.An mRNA vaccine against SARS-CoV-2 - preliminary report.N Engl J Med. 2020:NEJMoa2022483. doi:10.1056/NEJMoa2022483Sahu S, Hemlata, Verma A.Adverse events related to blood transfusion.Indian J Anaesth. 2014;58(5):543-51. doi:10.4103/0019-5049.144650
8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.InformedHealth.org Institute for Quality and Efficiency in Health Care (IQWiG).How does the immune system work?Eiz-Vesper B, Schmetzer HM.Antigen-presenting cells: potential of proven and new players in immune therapies.Transfus Med Hemother. 2020;47(6):429-431. doi:10.1159/000512729LibreTexts.11.3B: Antigen-presenting cells - B and T cells.Auladell M, Jia X, Hensen L, et al.Recalling the future: Immunological memory toward unpredictable influenza viruses.Front Immunol. 2019;10:1400. doi:10.3389/fimmu.2019.01400Sedova ES, Scherbinin DN, Lysenko AA, Alekseeva SV, Artemova EA, Shmarov MM.Non-neutralizing antibodies directed at conservative influenza antigens.Acta Naturae. 2019;11(4):22-32. doi:10.32607/20758251-2019-11-4-22-32Scohy A, Anantharajah A, Bodéus M, Kabamba-Mukadi B, Verroken A, Rodriguez-Villalobos H.Low performance of rapid antigen detection test as frontline testing for COVID-19 diagnosis.J Clin Virol. 2020;129:104455. doi:10.1016/j.jcv.2020.104455Jackson LA, Anderson EJ, Rouphael NG, Roberts PC, Makhene M, Coler RN, McCullough MP, Chappell JD, Denison MR, Stevens LJ, Pruijssers AJ, McDermott A, Flach B, Doria-Rose NA, Corbett KS, Morabito KM, O’Dell S, Schmidt SD, Swanson PA 2nd, Padilla M, Mascola JR, Neuzil KM, Bennett H, Sun W, Peters E, Makowski M, Albert J, Cross K, Buchanan W, Pikaart-Tautges R, Ledgerwood JE, Graham BS, Beigel JH; mRNA-1273 Study Group.An mRNA vaccine against SARS-CoV-2 - preliminary report.N Engl J Med. 2020:NEJMoa2022483. doi:10.1056/NEJMoa2022483Sahu S, Hemlata, Verma A.Adverse events related to blood transfusion.Indian J Anaesth. 2014;58(5):543-51. doi:10.4103/0019-5049.144650
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
InformedHealth.org Institute for Quality and Efficiency in Health Care (IQWiG).How does the immune system work?Eiz-Vesper B, Schmetzer HM.Antigen-presenting cells: potential of proven and new players in immune therapies.Transfus Med Hemother. 2020;47(6):429-431. doi:10.1159/000512729LibreTexts.11.3B: Antigen-presenting cells - B and T cells.Auladell M, Jia X, Hensen L, et al.Recalling the future: Immunological memory toward unpredictable influenza viruses.Front Immunol. 2019;10:1400. doi:10.3389/fimmu.2019.01400Sedova ES, Scherbinin DN, Lysenko AA, Alekseeva SV, Artemova EA, Shmarov MM.Non-neutralizing antibodies directed at conservative influenza antigens.Acta Naturae. 2019;11(4):22-32. doi:10.32607/20758251-2019-11-4-22-32Scohy A, Anantharajah A, Bodéus M, Kabamba-Mukadi B, Verroken A, Rodriguez-Villalobos H.Low performance of rapid antigen detection test as frontline testing for COVID-19 diagnosis.J Clin Virol. 2020;129:104455. doi:10.1016/j.jcv.2020.104455Jackson LA, Anderson EJ, Rouphael NG, Roberts PC, Makhene M, Coler RN, McCullough MP, Chappell JD, Denison MR, Stevens LJ, Pruijssers AJ, McDermott A, Flach B, Doria-Rose NA, Corbett KS, Morabito KM, O’Dell S, Schmidt SD, Swanson PA 2nd, Padilla M, Mascola JR, Neuzil KM, Bennett H, Sun W, Peters E, Makowski M, Albert J, Cross K, Buchanan W, Pikaart-Tautges R, Ledgerwood JE, Graham BS, Beigel JH; mRNA-1273 Study Group.An mRNA vaccine against SARS-CoV-2 - preliminary report.N Engl J Med. 2020:NEJMoa2022483. doi:10.1056/NEJMoa2022483Sahu S, Hemlata, Verma A.Adverse events related to blood transfusion.Indian J Anaesth. 2014;58(5):543-51. doi:10.4103/0019-5049.144650
InformedHealth.org Institute for Quality and Efficiency in Health Care (IQWiG).How does the immune system work?
Eiz-Vesper B, Schmetzer HM.Antigen-presenting cells: potential of proven and new players in immune therapies.Transfus Med Hemother. 2020;47(6):429-431. doi:10.1159/000512729
LibreTexts.11.3B: Antigen-presenting cells - B and T cells.
Auladell M, Jia X, Hensen L, et al.Recalling the future: Immunological memory toward unpredictable influenza viruses.Front Immunol. 2019;10:1400. doi:10.3389/fimmu.2019.01400
Sedova ES, Scherbinin DN, Lysenko AA, Alekseeva SV, Artemova EA, Shmarov MM.Non-neutralizing antibodies directed at conservative influenza antigens.Acta Naturae. 2019;11(4):22-32. doi:10.32607/20758251-2019-11-4-22-32
Scohy A, Anantharajah A, Bodéus M, Kabamba-Mukadi B, Verroken A, Rodriguez-Villalobos H.Low performance of rapid antigen detection test as frontline testing for COVID-19 diagnosis.J Clin Virol. 2020;129:104455. doi:10.1016/j.jcv.2020.104455
Jackson LA, Anderson EJ, Rouphael NG, Roberts PC, Makhene M, Coler RN, McCullough MP, Chappell JD, Denison MR, Stevens LJ, Pruijssers AJ, McDermott A, Flach B, Doria-Rose NA, Corbett KS, Morabito KM, O’Dell S, Schmidt SD, Swanson PA 2nd, Padilla M, Mascola JR, Neuzil KM, Bennett H, Sun W, Peters E, Makowski M, Albert J, Cross K, Buchanan W, Pikaart-Tautges R, Ledgerwood JE, Graham BS, Beigel JH; mRNA-1273 Study Group.An mRNA vaccine against SARS-CoV-2 - preliminary report.N Engl J Med. 2020:NEJMoa2022483. doi:10.1056/NEJMoa2022483
Sahu S, Hemlata, Verma A.Adverse events related to blood transfusion.Indian J Anaesth. 2014;58(5):543-51. doi:10.4103/0019-5049.144650
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