title: Myeloid suppressor cell-associated immune dysfunction in CSA1M fibrosarcoma tumor-bearing mice.
abstract: CSA1M tumor-bearing mice exhibited a severe immune dysfunction but the underlying mechanism remained unclear. In this study, we demonstrated that the myeloid suppressor cell (Mac-1(+)Gr-1(+) cells)-(MSC) related T cell immunosuppression in this tumor-bearing model. In mice at the late stage of CSA1M tumor-bearing (Late TB [8-10 weeks after cell inoculation in male BALB/c mice]), the percentages for CD4(+) and CD8(+) T cells decreased but Mac-1(+) cells increased in spleens with severe splenomegaly. There was no deficit for concanavalin A-induced CD4(+) and CD8(+) T cell proliferation, interferon-gamma (IFN-gamma) and interleukin (IL)-4 production, but delayed-type hypersensitivity reaction were attenuated. Analysis of cytokine production in unfractionated spleen cells showed a significant reduction of IFN-gamma and a marked increase of IL-10 and IL-4. In Late-TB mice, splenic MSC number intensively accumulated; the mRNA expressions of the signal transducer and activator of transcription 1, interferon regulatory factor 1 (IRF-1), and inducible nitric-oxide synthase (iNOS) were enhanced in MSC; the nitric oxide production and arginase enzyme activity increased in MSC as well. Furthermore, the concanavalin A-induced T cell proliferation was inhibited in the presence of lipopolysaccharide- or IFN-gamma-activated MSC from Late-TB mice, which could be reversed by the iNOS specific inhibitor L-NMMA. iNOS seemed to be required more than arginase for the suppressive activity of MSC. Taken together, our results suggest that the immune dysfunction in tumor-bearing mice might be causally associated with the accumulation of MSC and its tumor-favoring property.
authors: Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China.
authors: Ru
authors: R
authors: Zhou
authors: Pei-Lan
authors: PL
authors: He
authors: Yong-Xin
authors: YX
authors: Ren
authors: Wen-Hai
authors: WH
authors: Wang
authors: Rong-Yao
authors: RY
authors: Zhou
authors: Hua
authors: H
authors: Wan
authors: Shiro
authors: S
authors: Ono
authors: Hiromi
authors: H
authors: Fujiwara
authors: Jian-Ping
authors: JP
authors: Zuo
mesh_terms: D000818:Animals; D001119:Arginase / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D045744:Cell Line, Tumor; D003208:Concanavalin A / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D005354:Fibrosarcoma / Q000276:immunology* / Q000473:pathology*; D007108:Immune Tolerance; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D023461:Myeloid Progenitor Cells / Q000276:immunology*; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D013154:Spleen / Q000378:metabolism; D013163:Splenomegaly / Q000209:etiology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D016207:Cytokines; D003208:Concanavalin A; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D001119:Arginase