'''Antigen''' (disingkek '''Ag''') adolah zat apo sajo nan mampu manyababkan [[sistem imun]] maasilkan [[antibodi]] nan spesifik,<ref name="medlineag">{{Cite web|last=|first=|date=|title=Antigen: MedlinePlus Medical Encyclopedia|url=https://medlineplus.gov/ency/article/002224.htm|title=Antigen: MedlinePlus Medical Encyclopedia|last=|first=|date=|website=Medline Plus|access-date=2313 DesemberApril 20202021}}</ref> nan mampu baikatan jo sajumlah komponen sistem imun. Antigen marupoan [[molekul]] atau [[struktur]] molekul, saparti nan ado di bagian lua suatu [[patogen]], nan dapek diikek dek antibodi nan spesifik taadok antigen tasabuik atau dek [[Reseptor (biokimia)|reseptor]] antigen [[sel B]].<ref name="gen">{{Cite web|date=2020|title=Antibody|url=https://www.genome.gov/genetics-glossary/Antibody|title=Antibody|date=2020|publisher=National Human Genome Research Institute, US National Institutes of Health|access-date=13 OctoberApril 20202021}}</ref> Tanggapan yang diberikan oleh sistem imun disebut [[respons imun]]. Singkatan Ag sendiri marupoan kapanjangan dari ''antibody generator'' atau pambangkik antibodi.<ref>{{Cite book|last=Male|first=David K.|date=2006|url=https://books.google.com/books?id=gE6o5ZRJUawC&q=antibody+generator&pg=PA10|title=Immunology|publisher=Elsevier Health Sciences|isbn=978-0323033992|pages=10|language=en}}</ref>. Antigen "dijadian sasaran" dek antibodi.<ref name="gen" /> Satiok antibodi diproduksi sacaro khusus dek sistem imun untuak disasuaian jo antigen satalah [[Sel penyaji antigen|sel-sel]] dalam sistem imun basingguangan jo antigen tasabuik; proses iko digunoan untuak maidentifikasi antigen sacaro tapek, mamproduksi antibodi nan sasuai, nan mainisiasi timbuanyo [[Sistem imun adaptif|respons imun adaptif]].<ref name="gen" /><ref name="mlp">{{Cite web|date=28 September 2020|title=Immune system and disorders|url=https://medlineplus.gov/immunesystemanddisorders.html|title=Immune system and disorders|date=28 September 2020|publisher=MedlinePlus, US National Institute of Medicine|access-date=13 OctoberApril 20202021}}</ref> Antibodi dikatokan "sesuai" jo antigen dalam arti bahwsonyo inyo dapek mangikeknyo akibek adaptasi molekuler pado [[fragmen pangikek antigen]].<ref name="gen" /> Dalam kabanyakan kasus, antibodi hanyo dapek bareaksi nan mangikek satu antigen tatantu; dalam babarapo kasus lain, antibodi dapek [[Reaktivitas silang|bareaksi silang]] nan mangikek labiah dari ciek antigen. Antigen dapek barupo molekul [[protein]], [[peptida]] (rantai [[asam amino]]), jo [[polisakarida]] (rantai [[monosakarida]]/gula sadarano), samantaro molekul [[lipid]] jo [[asam nukleat]] manjadi antigen jiko hanyo digabuangan jo protein sarato polisakarida.<ref name="ReferenceA">{{Cite journal|last=Gavin|first=AL|last2=Hoebe|first2=K|last3=Duong|first3=B|last4=Ota|first4=T|last5=Martin|first5=C|last6=Beutler|first6=B|last7=Nemazee|first7=D|date=22 December 2006|title=Adjuvant-enhanced antibody responses in the absence of toll-like receptor signaling|journal=Science|volume=314|issue=5807|pages=1936–38|bibcode=2006Sci...314.1936G|doi=10.1126/science.1135299|pmc=1868398|pmid=17185603}}</ref>
Antigen dapek barasa dari dalam tubuh ("antigen-diri") atau dari lingkuangan lua ("bukan-diri" atau "benda asing").<ref name="mlp" /> Sistem imun maidentifikasi sarato manyarang antigen eksternal barupo "benda asing" nan biasonyo indak bareaksi taadok antigen-diri karano [[Seleksi negatif (imunologi)|seleksi negatif]] dari [[sel T]] dalam [[timus]].<ref>{{Cite journal|last=Gallucci|first=S|last2=Lolkema|first2=M|last3=Matzinger|first3=P|date=November 1999|title=Natural adjuvants: endogenous activators of dendritic cells|journal=Nature Medicine|volume=5|issue=11|pages=1249–55|doi=10.1038/15200|pmid=10545990}}</ref>
[[Vaksin]] adolah contoh dari antigen dalam bantuak imunogenik, nan sangajo diagiah kapado panarimo untuak mainduksi fungsi memori dari [[sistem imun adaptif]] taadok antigen dari patogen nan manyarang panarimo tasabuik. Vaksin taadok [[Influenza musiman|virus flu musiman]] adolah contoh nan umum.<ref name="cdc">{{Cite web|date=15 October 2019|title=Antigenic characterization|url=https://www.cdc.gov/flu/about/professionals/antigenic.htm|title=Antigenic characterization|date=15 October 2019|publisher=US Centers for Disease Control and Prevention|access-date=13 OctoberApril 20202021}}</ref>
== Etimologi ==
[[Paul Ehrlich]] manciptakan istilah [[antibodi]] (dalam bahaso Jerman ''Antikörper'') dalam [[Teori rantai samping|teori rantai sampingnyo]] pado akhir abad ke-19.<ref>{{Cite journal|last=Strebhardt|first=Klaus|last2=Ullrich, Axel|date=Jun 2008|title=Paul Ehrlich's magic bullet concept: 100 years of progress|journal=Nature Reviews Cancer|volume=8|issue=6|pages=473–80|doi=10.1038/nrc2394|issn=1474-1768|pmid=18469827}}</ref> Pada tahun 1899, [[László Detre (dokter)|Ladislas Deutsch (László Detre)]] (1874–1939) manamoi zat hipotetis nan ado di antaro konstituen bakteri jo antibodi sabagai "''substances immunogenes ou antigenes''" (zat antigenik atau imunogenik). Mulo nyo pacayo bahwasonyo zat tasabuik manjadi prekursor antibodi, samo saparti [[zimogen]] nan marupoan prekursor enzim. Tatapi, pado taun 1903, inyo mamahami bahwa antigen mainduksi produksi badan kekebalan (antibodi) jo manulih bahwa kato ''antigen'' adolah singkatan dari antisomatogen (''Immunkörperbildner''). ''[[Oxford English Dictionary|Kamus Bahasa Inggris Oxford]]'' manunjuakkan bahwa konstruksi logisnyo harusnyo "''anti(body)-gen''".<ref name="Lindenmann">{{Cite journal|last=Lindenmann, Jean|year=1984|title=Origin of the Terms 'Antibody' and 'Antigen'|url=http://www3.interscience.wiley.com/cgi-bin/fulltext/119531625/PDFSTART|journal=Scand. J. Immunol.|volume=19|issue=4|pages=281–85|doi=10.1111/j.1365-3083.1984.tb00931.x|pmid=6374880|access-date=2008-10-31|archive-date=2010-11-18|archive-url=https://www.webcitation.org/5uK08DeWS?url=http://www3.interscience.wiley.com/cgi-bin/fulltext/119531625/PDFSTART|archive-date=2010-11-18|access-date=13 April 2021|dead-url=yes}}</ref>
