Various immune functions of different types of immune cells are strongly impaired in patients with
head and neck squamous cell carcinoma (
HNSCC). Regulatory T-lymphocyte cells (Tregs) have been suggested to be involved in the
immunomodulation of immune responses and contribute to
HNSCC progression and immune escape. 'Naturally' occurring CD4+ CD25+ Tregs represent a small fraction within the different subsets of regulatory T cells, which are known to inhibit numerous immune functions of different types of immune cells. In this study, the cellular ratio of CD4+ CD25(high) Tregs to the entire population of CD4+ T-lymphocytes was analyzed with respect to different stages of
tumor progression and disease. Our data indicate a significantly high increased abundance of CD4+ CD25(high) CD127(low) Tregs in the peripheral blood of patients with
HNSCC, which in addition show modulated expression levels of various functional
proteins. Surprisingly, increased Treg levels were found even in patients with no active disease several years after
tumor resection, with no significant correlation to the individual
tumor stage. Additionally, increased levels of
chemokine CCL22, which mediates migration of Tregs to the
tumor, and upregulation of the corresponding receptor
protein CCR4 were observed in
HNSCC. Our data strongly suggest that
HNSCC leads to a permanent shift of Treg levels with hardly recognizable recovery rates.