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The liver as a crucial organ in the first line of host defense: the roles of Kupffer cells, natural killer (NK) cells and NK1.1 Ag+ T cells in T helper 1 immune responses
Author(s) -
Seki Shuhji,
Habu Yoshiko,
Kawamura Toshihiko,
Takeda Kazuyoshi,
Dobashi Hiroshi,
Ohkawa Takashi,
Hiraide Hoshio
Publication year - 2000
Publication title -
immunological reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.839
H-Index - 223
eISSN - 1600-065X
pISSN - 0105-2896
DOI - 10.1034/j.1600-0528.2002.017404.x
Subject(s) - biology , natural killer t cell , interleukin 12 , immune system , interleukin 21 , immunology , superantigen , cytotoxic t cell , lymphokine activated killer cell , kupffer cell , cd8 , t cell , biochemistry , in vitro
Summary: The liver remains a hematopoietic organ after birth and can produce all leukocyte lineages from resident hematopoietic stem cells. Hepatocytes produce acute phase proteins and complement in bacterial infections. Liver Kupffer cells are activated by various bacterial stimuli, including bacterial lipopolysaccharide (LPS) and bacterial superantigens, and produce interleukin (IL)‐12. IL‐12 and other monokines (IL‐18 etc.) produced by Kupffer cells activate liver natural killer (NK) cells and NK1.1 Ag+ T cells to produce interferon‐g and thereby acquire cytotoxicity against tumors and microbe‐infected cells. These liver leukocytes and the T helper 1 immune responses induced by them thus play a crucial role in the first line of defense against bacterial infections and hematogenous tumor metastases. However, if this defense system is inadequately activated, shock associated with multiple organ failure takes place. Activated liver NK1.1 Ag+ T cells and NK cells also cause hepatocyte injury. NK1.1 Ag+ T cells and another T‐cell subset with an intermediate T‐cell receptor, CD122+CD8+ T cells, can develop independently of thymic epithelial cells. Liver NK cells and NK1.1 Ag+ T cells physiologically develop in situ from their precursors, presumably due to bacterial antigens brought from the intestine via the portal vein. NK cells activated by bacterial superantigens or LPS are also probably involved in the vascular endothelial injury in Kawasaki disease.