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Antibodies (or Immunoglobulins)

Antibodies or Immunoglobulins are proteins capable of specific recognition and binding with an antigen. Antibodies carries antigen-binding sites that bind non-covalently with the corresponding antigen epitope. Antibodies are produced in the body by the B lymphocytes at the cell surface and are secreted by plasma cells, in response to stimulation by antigen.

The molecular synthesis of the immunoglobulin (IG) and T cell receptor (TR) chains includes complex mechanisms such as DNA rearrangements, nucleotide insertions and deletions, and for the IG, somatic hypermutations. This leads one individual to potentially produce more than 1012 different IG or TR. The limiting factor is not the diversity mechanisms but the number of B and T cells that an organism can produce.

IG or immunoglobulin or antibody, complete or partial (Fab, Fab', scFv). An IG (or antibody fragment) must contain at least one variable domain (for example VH) to be designated with the suffix (stem) '-mab' in INN. IG can be radiolabelled or conjugated (to a chelator, a toxin, an interleukin, a pegol, etc.) for diagnostic or therapeutic purpose.


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  1. Ab: Antibody
  2. BcR: B cell receptor
  3. Ig: Immunoglobulin (for classes and subclasses, and in general)
  4. IG: Immunoglobulin (for gene, locus and for IMGT standardized data)
  1. GO:0019814 immunoglobulin complex

[1] Lefranc, M.-P. and Lefranc, G., The Immunoglobulin FactsBook, Academic Press, 458 pages (2001) ISBN:012441351X.