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The intracellular granzyme B inhibitor, proteinase inhibitor 9, is up-regulated during accessory cell maturation and effector cell degranulation, and its overexpression enhances CTL potency
被引:139
作者:
Hirst, CE
Buzza, MS
Bird, CH
Warren, HS
Cameron, PU
Zhang, ML
Ashton-Rickardt, PG
Bird, PI
机构:
[1] Monash Univ, Dept Biochem & Mol Biol, Clayton, Vic 3800, Australia
[2] Australian Natl Univ, John Curtin Sch Med Res, Div Cell Biol & Immunol, Canberra, ACT 2601, Australia
[3] Univ Melbourne, Dept Microbiol & Immunol, Parkville, Vic 3052, Australia
[4] Univ Chicago, Dept Pathol, Ben May Inst Canc Res, Chicago, IL 60637 USA
[5] Univ Chicago, Gwen Knapp Ctr Lupus & Immunol Res, Chicago, IL 60637 USA
关键词:
D O I:
10.4049/jimmunol.170.2.805
中图分类号:
R392 [医学免疫学];
Q939.91 [免疫学];
学科分类号:
100102 ;
摘要:
Granzyme B (grB) is a serine proteinase released by cytotoxic lymphocytes (CLs) to kill abnormal cells. GrB-mediated apoptotic pathways are conserved in nucleated cells; hence, CLs require mechanisms to protect against ectopic or misdirected grB. The nucleocytoplasmic serpin, proteinase inhibitor 9 (PI-9), is a potent inhibitor of grB that protects cells from grB-mediated apoptosis in model systems. Here we show that PI-9 is present in CD4(+) cells, CD8(+) T cells, NK cells, and at lower levels in B cells and myeloid cells. PI-9 is up-regulated in response to grB production and degranulation, and associates with grB-containing granules in activated CTLs and NK cells. Intracellular complexes of PI-9 and grB are evident in NK cells, and overexpression of PI-9 enhances CTL potency, suggesting that cytoplasmic grB, which may threaten CL viability, is rapidly inactivated by PI-9. Because dendritic cells (DCs) acquire characteristics similar to those of target cells to activate naive CD8(+) T cells and therefore may also require protection against grB, we investigated the expression of PI-9 in DCs. PI-9 is evident in thymic DCs (CD3(-) CD4(+), CD8(-), CD45(+)), tonsillar DCs, and DC subsets purified from peripheral blood (CD16(+) monocytes and CD123(+) plasmacytoid DCs). Furthermore, PI-9 is expressed in monocyte-derived DCs and is up-regulated upon TNF-alpha-induced maturation of monocyte-derived DCs. In conclusion, the presence and subcellular localization of PI-9 in leukocytes and DCs are consistent with a protective role against ectopic or misdirected grB during an immune response.
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页码:805 / 815
页数:11
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