title: B7-H1 on myeloid-derived suppressor cells in immune suppression by a mouse model of ovarian cancer.
abstract: Myeloid-derived suppressor cells (MDSCs) accumulate in tumor-bearing hosts and are associated with immune suppression. Here, we described high level of expression of B7-H1 (CD274), PD-1 (CD279) and CTLA4 (CD152) by Gr-1(+)CD11b(+) MDSCs obtained from both ascites and spleens of mice bearing the 1D8 ovarian carcinoma, whereas B7-DC (CD273), CD40 and CD86 were absent. In contrast, B7-H1, PD-1 and CTLA-4 expression was not detected on Gr-1(+)CD11b(+) cells from naive mice. Expression of B7-H1 by Gr-1(+)CD11b(+) cells from naive mice could be induced by co-culture with 1D8 ovarian carcinoma cells. Gr-1(+)CD11b(+) cells derived from 1D8 tumor-bearing mice markedly suppressed antigen-specific immune responses, whereas Gr-1(+)CD11b(+) cells from naive mice did not. siRNA-mediated knockdown of B7-H1 in Gr-1(+)CD11b(+) cells of 1D8 tumor-bearing mice alleviated suppression of antigen-specific immune responses. Suppression of antigen-specific immune responses via B7-H1 on Gr-1(+)CD11b(+) myeloid cells was mediated by CD4(+)CD25(+) Foxp3(+) T regulatory cells and required PD-1. Antibody blockade of either B7-H1 or PD-1 retarded the growth of 1D8 tumor in mice. This suggests that expression of B7-H1 on Gr-1(+)CD11b(+) myeloid cells triggered by the 1D8 mouse model of ovarian carcinoma suppresses antigen-specific immunity via interaction with PD-1 on CD4(+)CD25(+) Foxp3(+) regulatory T cells.
authors.affiliation: Department of Immunology, Nankai University School of Medicine, Nankai University, 300071, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.forename: Bin
authors.initials: B
authors.lastname: Zeng
authors.forename: Zhuohan
authors.initials: Z
authors.lastname: Zhang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Rongcun
authors.initials: R
authors.lastname: Yang
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D000943:Antigens, Differentiation / Q000276:immunology / Q000378:metabolism; D018122:B7-1 Antigen / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D060890:B7-H1 Antigen; D039481:CD11b Antigen / Q000096:biosynthesis / Q000276:immunology; D060908:CTLA-4 Antigen; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000276:immunology; D016130:Immunophenotyping; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D022423:Myeloid Cells / Q000276:immunology; D010051:Ovarian Neoplasms / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D010455:Peptides / Q000235:genetics / Q000276:immunology; D061026:Programmed Cell Death 1 Receptor; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000276:immunology; D014162:Transfection
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018122:B7-1 Antigen; D060890:B7-H1 Antigen; D039481:CD11b Antigen; D060908:CTLA-4 Antigen; C498919:Cd274 protein, mouse; C556707:Ctla4 protein, mouse; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D008562:Membrane Glycoproteins; C491383:Pdcd1 protein, mouse; D010455:Peptides; D061026:Programmed Cell Death 1 Receptor; D034741:RNA, Small Interfering