The granzyme B inhibitor, PI-9, is present in endothelial and mesothelial cells, suggesting that it protects bystander cells during immune responses.
Cell Immunol
; 210(1): 21-9, 2001 May 25.
Article
en En
| MEDLINE
| ID: mdl-11485349
Proteinase inhibitor 9 (PI-9) is a 42-kDa human intracellular serpin present in cytotoxic lymphocytes (CLs). PI-9 is an extremely efficient inhibitor of the pro-apoptotic CL granule proteinase granzyme B and is thought to function in the cytosol of CLs to protect against apoptosis induced by endogenously expressed or released granzyme B, particularly during target cell killing. Here we show by immunohistochemistry that PI-9 is also present in endothelial cells, in every tissue examined. Cultured endothelial cells express functional PI-9 (as assessed by binding to recombinant granzyme B) localized to the cytoplasm and nucleus. Immunohistochemistry also showed PI-9 in mesothelial cells, and this was confirmed by analysis of primary cells cultured from pleural and serous effusions. Granzyme B expression was not detected in either endothelial or mesothelial cells. In both cell types, PI-9 is up-regulated at the mRNA and protein level by exposure to the phorbol ester PMA, consistent with a response to inflammatory stimuli. We postulate that PI-9 is present in these lining cell types to protect against misdirected, free granzyme B released during a local immune response.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Serina Endopeptidasas
/
Inhibidores de Serina Proteinasa
/
Serpinas
/
Endotelio
/
Epitelio
Límite:
Humans
Idioma:
En
Revista:
Cell Immunol
Año:
2001
Tipo del documento:
Article
País de afiliación:
Australia
Pais de publicación:
Países Bajos