title: Gamma irradiation alters the phenotype and function of CD4+CD25+ regulatory T cells.
abstract: To examine the effects of gamma irradiation on Tregs, changes in phenotype and suppression function in Tregs treated with or without gamma ray were analyzed. Purified CD4(+)CD25(+) regulatory T cells were irradiated at different dosages with a (137)Cs source gamma ray at 4.8 Gy/min. After culture, the phenotype and function changes were determined by flow cytometry and [(3)H]-thymidine incorporation, respectively. A dose-dependent reduction of Tregs proliferation in response to gamma irradiation was noted, which paralleled the apoptosis induction of Tregs. Gamma irradiation downregulated the Tregs expression of CD45RO, CD62L, FOXP3, membrane TGF-beta, but upregulated Bax and GITR. High dose gamma irradiation (30 Gy) significantly abolished the suppression of Tregs on CD4(+)CD25(-) T cells proliferation. Thus Tregs not only influences the phenotype but also alters their suppressive capacities. Our findings suggest that radiotherapy may be an important strategy to alter the immunologic balance of Tregs and effector cells in cancer therapy.
authors.affiliation: Section of Hepatobiliary Diseases, Department of Medicine, University of Florida, Gainesville, FL 32610-0214, USA. caom@medicine.ufl.edu
authors.forename: Mengde
authors.initials: M
authors.lastname: Cao
authors.forename: Roniel
authors.initials: R
authors.lastname: Cabrera
authors.forename: Yiling
authors.initials: Y
authors.lastname: Xu
authors.forename: Chen
authors.initials: C
authors.lastname: Liu
authors.forename: David
authors.initials: D
authors.lastname: Nelson
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D049109:Cell Proliferation / Q000528:radiation effects; D051858:Forkhead Transcription Factors / Q000378:metabolism; D005720:Gamma Rays; D006801:Humans; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism*; D019041:L-Selectin / Q000378:metabolism; D017493:Leukocyte Common Antigens / Q000378:metabolism; D009369:Neoplasms / Q000532:radiotherapy; D010641:Phenotype; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D016212:Transforming Growth Factor beta / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D053645:Interleukin-2 Receptor alpha Subunit; D016212:Transforming Growth Factor beta; D051028:bcl-2-Associated X Protein; D019041:L-Selectin; D017493:Leukocyte Common Antigens