Antigens

Definition

Antigens are substances that can trigger an immune response in the body, typically recognized as foreign by the immune system. They are often found on the surface of pathogens like bacteria and viruses, as well as on other cells, including allergens and some cancer cells. The interaction between antigens and immune cells is crucial for the development of immunity and the effectiveness of vaccines.

5 Must Know Facts For Your Next Test

1. Antigens can be proteins, polysaccharides, lipids, or nucleic acids that are recognized by the immune system.
2. Vaccines introduce antigens in a controlled way, allowing the body to build immunity without causing disease.
3. The strength of the immune response to an antigen depends on its immunogenicity, which is influenced by factors like its foreignness and size.
4. Antigens are essential for distinguishing between self and non-self entities in the body, helping to prevent autoimmune diseases.
5. Different types of vaccines may use live attenuated, inactivated, subunit, or messenger RNA (mRNA) technologies to present antigens and stimulate immunity.

Review Questions

• How do antigens play a role in vaccine development and efficacy?
  • Antigens are crucial for vaccine development as they provide the specific targets that the immune system recognizes to mount a response. Vaccines introduce antigens in a safe manner—either through weakened pathogens or pieces of them—allowing the body to develop memory cells without causing illness. This enables a quicker and stronger immune response upon actual exposure to the pathogen.
• Compare and contrast different types of vaccines in terms of their use of antigens and their mechanisms of action.
  • Different types of vaccines utilize various forms of antigens to induce immunity. Live attenuated vaccines use weakened forms of pathogens that still elicit a strong immune response. Inactivated vaccines contain killed pathogens, which require multiple doses for effectiveness. Subunit vaccines include only specific parts of the antigen, while mRNA vaccines deliver genetic instructions for cells to produce the antigen themselves. Each type stimulates the immune system differently but ultimately aims to create lasting immunity.
• Evaluate the impact of antigen variability on vaccine design and public health strategies.
  • Antigen variability poses significant challenges for vaccine design as changes in pathogen surface proteins can reduce vaccine efficacy. For instance, influenza viruses frequently mutate, necessitating annual updates to vaccines. This variability affects public health strategies by requiring ongoing surveillance and adaptation of vaccination campaigns. Understanding how antigens change is essential for creating effective vaccines and maintaining herd immunity within populations.

Related terms

Immunogenicity:

The ability of an antigen to provoke an immune response, leading to the production of antibodies or activation of T cells.

Epitope:

The specific part of an antigen that is recognized by the immune system, particularly by antibodies or T cell receptors.

Vaccine: A biological preparation that provides active acquired immunity to a particular infectious disease, often containing weakened or inactive parts of an antigen.