Figure 2. Changes in the CD4+ T-cell compartment after oncological therapies.

(a) Decreased total CD4+ T cell frequency is accompanied by increased frequency of CD4⁺CD39⁺ Treg. Density plots show data from representative HNSCC subjects selected from each study group. Gates are set on the lymphocyte window (left column), and on the CD4⁺ T-cell subset (right column). (b) Negative associations between percentages (left) or absolute numbers (right) of total CD4⁺ T cells and the percentages of CD4⁺CD39⁺CD25⁺ Treg in the circulation of HNSCC patients treated with SRG or CRT. (c) A positive correlation between the frequency of CD4⁺CD39⁺CD25⁺ Treg and CD4⁺CD39⁺CD25^neg cells in the peripheral circulation. (d) A positive correlation between the frequency of CD4⁺CD25^high and CD4⁺CD39⁺CD25⁺ Treg subsets in the peripheral circulation of NC as well as all HNSCC patients.