Antigens and Immunogens

Definition : Antigens

  • Foreign substance that provokes the antibody production when entered in body.
  • Substance which, when introduced into the body, stimulates the production of antibodies with which it reacts in specific and observable manner.
  • Substances that can induce a specific immune response and specifically bind products of immune response in vitro or in vivo.
  • It can be described as a substance that reacts with the products of a specific immune response. The word originated from the notion that they can stimulate antibody generation.
  • Substances that can be recognized by the immunoglobulin receptor of B cells, or by the Tcell receptor when complexed with MHC, are called antigens.

Definition : Immunogens

  • Immunogens are substances capable of stimulating the immune system (that is, eliciting B or T cell response) and reacting with the product of such stimulation

“Not all antigens are immunogens but all immunogens are antigens”


Immunogenicity vs Antigenicity

  • Immunogenicity is the ability to induce a humoral and/or cell mediated immune response

B cells + Antigen —->  Plasma cells + Memory Cells

T cells + Antigen + MHC  —> T effector cells + Memory Cells

  • Antigenicity is the ability to combine specifically with the final products of the immune response (i.e. secreted antibodies and/or surface receptors on T-cells).
  • Although all molecules that have the property of immunogenicity also have the property of antigenicity, the reverse is not true.
  • An immunogen is able to induce an immune response, whereas an antigen is able to combine with the products of an immune response once they are made.

Binod G C

I'm Binod G C (MSc), a PhD candidate in cell and molecular biology who works as a biology educator and enjoys scientific blogging. My proclivity for blogging is intended to make notes and study materials more accessible to students.

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