BMC Cancer 2008, 8:57 http://www.biomedcentral.com/1471-2407/8/57 models [47]. Furthermore, elimination of Tregs by IL-2- conjugated to diphtheria-toxin (ONTAK) enhanced vac- cine-mediated anti-tumor immunity in cancer patients [56]. Interestingly, a very recent study, in an animal model of renal cell carcinoma, has shown that only triple treat- ment consisting of tumor vaccine, B7-H1 blockade, and Tregs depletion can result in a complete tumor regression and long lasting protective immunity [57] supporting the use of triple therapy treatment of cancer patients. Conclusion In conclusion, we have shown a concurrent and abundant infiltration of different immune suppressive subsets of T lymphocytes in the microenvironment of high-risk breast cancer patients. This interesting observation suggests the development of a new therapeutic modalities aiming at targeting B7-H1/PD-1 and Tregs in addition to still-devel- oping immunotherapy. Competing interests The author(s) declare that they have no competing inter- ests. Authors' contributions HG designed the study, carried out the immunohisto- chemistry for B7-H1, coordinated the work and wrote the manuscript. EB carried out immunohistochemistry of PD- 1, FOXP3, and CD8 molecules. AT (anatomical patholo- gist) read and interpreted the sections. NE (statistician) carried out the statistical analysis. TA (medical oncologist) participated in conceiving the study and provided the clinical data. SD (principal investigator) wrote the pro- posal, conceived, supervised the study, and wrote the manuscript. All authors read and approved the final man- uscript. Acknowledgements We are very grateful to the administration of the Research Centre and the Office of Research Affairs (ORA) for their support. This work was spon- sored by KFSH&RC (RAC # 2030 034). We would like to thank Drs. Monther Al-Alwan and Ayodele Alaiya for critical review for the manu- script, and Zuha Al-Mukhlafi and Manogaran Pulicat for analyzing the FACS data. References 1. Ahmad M, Rees RC, Ali SA: Escape from immunotherapy: pos- sible mechanisms that influence tumor regression/progres- sion. Cancer Immunology, Immunotherapy 2004, 53(10):844-854. 2. Rivoltini L, Canese P, Huber V, Iero M, Pilla L, Valenti R, Fais S, Loz- upone F, Casati C, Castelli C, Parmiani G: Escape strategies and reasons for failure in the interaction between tumour cells and the immune system: how can we tilt the balance towards immune-mediated cancer control? Expert Opinion on Biological Therapy 2005, 5(4):463-476. 3. Seliger B: Strategies of tumor immune evasion. Biodrugs 2005, 19(6):347-354. 4. Freeman GJ, Long AJ, Iwai Y, Bourque K, Chernova T, Nishimura H, Fitz LJ, Malenkovich N, Okazaki T, Byrne MC, Horton HF, Fouser L, Carter L, Ling V, Bowman MR, Carreno BM, Collins M, Wood CR, Honjo T: Engagement of the PD-1 immunoinhibitory recep- tor by a novel B7 family member leads to negative regula- tion of lymphocyte activation. J Exp Med 2000, 192(7):1027-1034. 5. Dong H, Zhu G, Tamada K, Chen L: B7-H1, a third member of the B7 family, co-stimulates T-cell proliferation and inter- leukin-10 secretion. Nat Med 1999, 5(12):1365-1369. 6. Dong H, Strome SE, Salomao DR, Tamura H, Hirano F, Flies DB, Roche PC, Lu J, Zhu G, Tamada K, Lennon VA, Celis E, Chen L: Tumor-associated B7-H1 promotes T-cell apoptosis: a potential mechanism of immune evasion. Nat Med 2002, 8(8):793-800. 7. Selenko-Gebauer N, Majdic O, Szekeres A, Hofler G, Guthann E, Korthauer U, Zlabinger G, Steinberger P, Pickl WF, Stockinger H, Knapp W, Stockl J: B7-H1 (programmed death-1 ligand) on dendritic cells is involved in the induction and maintenance of T cell anergy. J Immunol 2003, 170(7):3637-3644. 8. Iwai Y, Ishida M, Tanaka Y, Okazaki T, Honjo T, Minato N: Involve- ment of PD-L1 on tumor cells in the escape from host immune system and tumor immunotherapy by PD-L1 block- ade. Proc Natl Acad Sci USA 2002, 99(19):12293-12297. 9. Konishi J, Yamazaki K, Azuma M, Kinoshita I, Dosaka-Akita H, Nishimura M: B7-H1 expression on non-small cell lung cancer cells and its relationship with tumor-infiltrating lymphocytes and their PD-1 expression. Clin Cancer Res 2004, 10(15):5094-5100. 10. Nomi T, Sho M, Akahori T, Hamada K, Kubo A, Kanehiro H, Naka- mura S, Enomoto K, Yagita H, Azuma M, Nakajima Y: Clinical signif- icance and therapeutic potential of the programmed death- 1 ligand/programmed death-1 pathway in human pancreatic cancer. Clin Cancer Res 2007, 13(7):2151-2157. 11. Ohigashi Y, Sho M, Yamada Y, Tsurui Y, Hamada K, Ikeda N, Mizuno T, Yoriki R, Kashizuka H, Yane K, Tsushima F, Otsuki N, Yagita H, Azuma M, Nakajima Y: Clinical significance of programmed death-1 ligand-1 and programmed death-1 ligand-2 expres- sion in human esophageal cancer. Clin Cancer Res 2005, 11(8):2947-2953. 12. Strome SE, Dong H, Tamura H, Voss SG, Flies DB, Tamada K, Salo- mao D, Cheville J, Hirano F, Lin W, Kasperbauer JL, Ballman KV, Chen L: B7-H1 blockade augments adoptive T-cell immuno- therapy for squamous cell carcinoma. Cancer Res 2003, 63(19):6501-6505. 13. Thompson RH, Gillett MD, Cheville JC, Lohse CM, Dong H, Webster WS, Krejci KG, Lobo JR, Sengupta S, Chen L, Zincke H, Blute ML, Strome SE, Leibovich BC, Kwon ED: Costimulatory B7-H1 in renal cell carcinoma patients: Indicator of tumor aggressive- ness and potential therapeutic target. Proc Natl Acad Sci U S A 2004, 101(49):17174-17179. 14. Thompson RH, Kuntz SM, Leibovich BC, Dong H, Lohse CM, Web- ster WS, Sengupta S, Frank I, Parker AS, Zincke H, Blute ML, Sebo TJ, Cheville JC, Kwon ED: Tumor B7-H1 is associated with poor prognosis in renal cell carcinoma patients with long-term fol- low-up. Cancer Res 2006, 66(7):3381-3385. 15. Wintterle S, Schreiner B, Mitsdoerffer M, Schneider D, Chen L, Meyermann R, Weller M, Wiendl H: Expression of the B7-related molecule B7-H1 by glioma cells: a potential mechanism of immune paralysis. Cancer Res 2003, 63(21):7462-7467. 16. Hamanishi J, Mandai M, Iwasaki M, Okazaki T, Tanaka Y, Yamaguchi K, Higuchi T, Yagi H, Takakura K, Minato N, Honjo T, Fujii S: Pro- grammed cell death 1 ligand 1 and tumor-infiltrating CD8+ T lymphocytes are prognostic factors of human ovarian can- cer. Proc Natl Acad Sci U S A 2007, 104(9):3360-3365. 17. Thompson RH, Dong H, Lohse CM, Leibovich BC, Blute ML, Cheville JC, Kwon ED: PD-1 is expressed by tumor-infiltrating immune cells and is associated with poor outcome for patients with renal cell carcinoma. Clin Cancer Res 2007, 13(6):1757-1761. 18. Ghebeh H, Mohammed S, Al-Omair A, Qattan A, Lehe C, Al-Qudaihi G, Elkum N, Alshabanah M, Bin Amer S, Tulbah A, Ajarim D, Al- Tweigeri T, Dermime S: The B7-H1 (PD-L1) T lymphocyte- inhibitory molecule is expressed in breast cancer patients with infiltrating ductal carcinoma: correlation with impor- tant high-risk prognostic factors. Neoplasia 2006, 8(3):190-198. 19. Thornton AM, Shevach EM: CD4+CD25+ immunoregulatory T cells suppress polyclonal T cell activation in vitro by inhibit- ing interleukin 2 production. Journal of Experimental Medicine 1998, 188(2):287-296. Page 10 of 12 (page number not for citation purposes)