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Hepatic natural killer cells exclusively kill splenic/blood natural killer‐resistant tumor cells by the perforin/granzyme pathway
Author(s) -
Vermijlen David,
Luo Dianzhong,
Froelich Christopher J,
Medema Jan Paul,
Kummer Jean Alain,
Willems Erik,
Braet Filip,
Wisse Eddie
Publication year - 2002
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1189/jlb.72.4.668
Subject(s) - perforin , granzyme , biology , interleukin 21 , granzyme b , lymphokine activated killer cell , interleukin 12 , cd49b , granzyme a , cytotoxic t cell , natural killer t cell , natural killer cell , nk 92 , microbiology and biotechnology , cancer research , immunology , immune system , t cell , cd8 , in vitro , biochemistry
Hepatic natural killer (NK) cells are located in the liver sinusoids adherent to the endothelium. Human and rat hepatic NK cells induce cytolysis in tumor cells that are resistant to splenic or blood NK cells. To investigate the mechanism of cell death, we examined the capacity of isolated, pure (90%) rat hepatic NK cells to kill the splenic/blood NK‐resistant mastocytoma cell line P815. Cell death was observed and quantified by fluorescence and transmission electron microscopy, DNA fragmentation, and 51 Cr release. RNA and protein expression were determined by real time reverse transcription‐polymerase chain reaction and Western blotting. Compared with splenic NK cells, hepatic NK cells expressed higher levels of perforin and granzyme B and readily induced apoptosis in P815 cells. Although P815 cells succumbed to recombinant Fas ligand (FasL) or isolated perforin/granzyme B, hepatic NK cells used only the granule pathway to kill this target. In addition, hepatic NK cells and sinusoidal endothelial cells strongly expressed the granzyme B inhibitor, protease inhibitor 9 (PI‐9)/serine PI‐6 (SPI‐6), and P815 cells and hepatocytes were negative. Transfection of target cells with this inhibitor resulted in complete resistance to hepatic NK cell‐induced apoptosis. In conclusion, hepatic NK cells kill splenic/blood NK‐resistant/FasL‐sensitive tumor cells exclusively by the perforin/granzyme pathway. Serine protease inhibitor PI‐9/SPI‐6 expression in liver sinusoidal endothelial cells may protect the liver microenvironment from this highly active perforin/granzyme pathway used to kill metastasizing cancer cells.