Publication Date:
2008-06-01
Description:
Regulatory T (Treg) cells contribute to immune evasion by malignancies. To investigate their importance in non-Hodgkin lymphoma (NHL), we enumerated Treg cells in peripheral blood mononuclear cells (PBMCs) and involved tissues from 30 patients. CD25+FoxP3+CD127lowCD4+ Treg cells were increased markedly in PBMCs (median = 20.4% CD4 T cells, n = 20) versus healthy controls (median = 3.2%, n = 13, P 〈 .001) regardless of lymphoma subtype, and correlated with disease stage and serum lactate dehydrogenase (Rs = 0.79, P 〈 .001). T-cell hyporesponsiveness was reversed by depleting CD25+ cells, or by adding anti–CTLA-4, supporting the view that Treg cells explain the systemic immunosuppression seen in NHL. A high proportion of Treg cells was also present in involved tissues (median = 38.8% CD4 T cells, n = 15) versus reactive nodes (median = 11.6%, n = 2, P = .02). When autologous CD25− PBMC fractions were incubated with tumor cells from patients (n = 6) in vitro, there was consistent strong induction and then expansion of cells with the CD4+CD25+FoxP3+ phenotype of classic “natural” Treg cells. This population was confirmed to be suppressive in function. Direct cell-cell interaction of tumor cells with CD25− PBMCs was important in Treg induction, although there was heterogeneity in the mechanisms responsible. We conclude that NHL cells are powerful inducers of Treg cells, which may represent a new therapeutic target.
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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