Topic Completed: 1 November 2013

Minor changes: 27 August 2020

Copyright: 2003-2020,, Inc.

PubMed Search: alpha-1-antichymotrypsin[title]

Nat Pernick, M.D.
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Cite this page: Pernick N. Alpha-1-antichymotrypsin. website. Accessed October 28th, 2020.
Definition / general
  • Also called α1-ACT
  • Acute phase protein / plasma protease inhibitor, mainly produced by liver in response to cytokines such as oncostatin M
  • May limit tissue damage produced by excessive inflammation associated proteolysis
  • Also localizes to nuclei of hepatic cells to control chromatin condensation and proliferation (Gastroenterology 2013;144:818)
  • Homologous to alpha-1-antitrypsin
  • Chymotrypsin is digestive enzyme produced by pancreas
Clinical features
Uses by pathologists
Microscopic (histologic) images

Images hosted on other servers:

Breast: primary acinic cell carcinoma (fig F)

Skin: nevi and melanoma

Stomach: hepatoid
adenocarcinoma (fig C)

Positive staining - normal
  • Histiocytes, reticulum cells
Positive staining - tumors
  • Acinic / acinar cell carcinomas of breast, pancreas, salivary gland tumors
  • Hepatoid adenocarcinoma of stomach (World J Gastroenterol 2013;19:4437)
  • Solid-pseudopapillay neoplasm of pancreas
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