Objective: to investigate the role of Toll-like receptor (TLR) signaling and T-regulatory (T-reg) cells in patients with head and neck squamous cell carcinoma (HNSCC).
Design: multicolor flow cytometry was used to study the frequency and phenotype of CD4(+)CD25(+)CD127(-) T-reg cells and CD4(+)CD25(-)CD127(+) T-effector (T-eff) cells in peripheral blood mononuclear cells (PBMCs).
Setting: all patients were seen at the outpatient clinic at the Department of Otorhinolaryngology at the University of Duisburg-Essen from March 1, 2009, through December 31, 2009.
Patients: eleven patients with HNSCC and 10 healthy donors (HDs) were studied. T-reg and T-eff cells were isolated from PBMCs using a magnetic bead-activated cell-sorting technique.
Main outcome measures: proliferation of T-eff cells and suppressor activity of T-reg cells were assessed in functional assays after preincubation with the TLR4 ligand heat shock protein 60 or lipopolysaccharide in the presence or absence of neutralizing antibody against TLR4.
Results: frequency of T-reg cells in PBMCs was strongly increased in patients with HNSCC vs HDs. Isolation of T-reg cells from PBMCs of patients with HNSCC showed a significantly higher expression of TLR4, TLR6, TLR9, and TLR10 compared with HDs, whereas TLR2 was not detectable. After incubation with heat shock protein 60 or lipopolysaccharide, the suppressive function of T-reg cells was significantly increased (1.14- and 1.44-fold, respectively), whereas the proliferation capacity of T-eff cells remained unchanged. This effect was reversed after TLR4 inhibition on T-reg cells.
Conclusion: the TLR ligation on T-reg cells may contribute to tumor-mediated immune suppression by enhancing their suppressive activity.