A unique subset of CD4+CD25highFoxp3+ T cells secreting interleukin-10 and transforming growth factor-beta1 mediates suppression in the tumor microenvironment.
OBJECTIVE
Immunosuppression, including that mediated by CD4(+)CD25(high)Foxp3(+) regulatory T cells (Treg), is a characteristic feature of head and neck squamous cell carcinoma (HNSCC). Tregs with a distinct phenotype in tumor-infiltrating lymphocytes (TIL) contribute to local immune suppression.


METHODS
The frequency and phenotype of Treg in TIL and/or peripheral blood mononuclear cells (PBMC) in 15 HNSCC patients and PBMC in 15 normal controls were compared. Single-cell sorted CD4(+)CD25(high) T cells were tested for regulatory function by coculture with carboxyfluorescein diacetate succinimidyl ester-labeled and activated autologous CD4(+)CD25(-) responder T cells. Transwell inserts separating Treg from responders and neutralizing interleukin-10 (IL-10) or transforming growth factor-beta1 (TGF-beta1) antibodies were used to evaluate the mechanisms used by Treg to suppress responder cell proliferation.


RESULTS
In TIL, CD25(+) cells were enriched in the CD3(+)CD4(+) subset (13 +/- 3%) relative to circulating CD3(+)CD4(+) T cells (3 +/- 0.7%) in HNSCC patients (P < or = 0.01) or normal controls (2 +/- 1.5%; P < or = 0.001). Among the CD3(+)CD4(+) subset, CD25(high) Treg represented 3 +/- 0.5% in TIL, 1 +/- 0.3% in PBMC, and 0.4 +/- 0.2% in normal controls. Tregs in TIL were GITR(+), IL-10(+), and TGF-beta1(+), although circulating Treg up-regulated CD62L and CCR7 but not GITR, IL-10, or TGF-beta1. Treg in TIL mediated stronger suppression (P < or = 0.001) than Treg in PBMC of HNSCC patients. The addition of neutralizing IL-10 and TGF-beta antibodies almost completely abrogated suppression (5 +/- 2.51%). Transwell inserts partly prevented suppression (60 +/- 5% versus 95 +/- 5%).


CONCLUSIONS
Suppression in the tumor microenvironment is mediated by a unique subset of Treg, which produce IL-10 and TGF-beta1 and do not require cell-to-cell contact between Treg and responder cells for inhibition.
University of Pittsburgh Cancer Institute, Pennsylvania 15213-1863, USA.
Laura
L
Strauss
Christoph
C
Bergmann
Miroslaw
M
Szczepanski
William
W
Gooding
Jonas T
JT
Johnson
Theresa L
TL
Whiteside
D000328:Adult; D000368:Aged; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002294:Carcinoma, Squamous Cell / Q000276:immunology / Q000473:pathology; D049109:Cell Proliferation; D005260:Female; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D006258:Head and Neck Neoplasms / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007108:Immune Tolerance; D007165:Immunosuppression Therapy; D016753:Interleukin-10 / Q000378:metabolism*; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism*; D008213:Lymphocyte Activation; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000276:immunology*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*
C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D053645:Interleukin-2 Receptor alpha Subunit; D012333:RNA, Messenger; C508960:TGFB1 protein, human; D053773:Transforming Growth Factor beta1; D016753:Interleukin-10