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).
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).
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.
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.
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.
The TLR ligation on T-reg cells may contribute to tumor-mediated immune suppression by enhancing their suppressive activity.