Fig. 3

In-vitro PD-1 blockade in HPV16 E6-stimulated LN-, LN+ and PT single cell suspensions. The IFNγ ELISPOT reactivity is expressed as number of spots per 100,000 T cells. a IFNγ T cell reactivity to a set of 15-mer overlapping peptides covering the HPV16 E6 protein sequence; enhanced reactivity upon PD-1 blockade was observed in 4/4 responders in the LN+ (n = 7) group and in 1/4 responders in the PT (n = 7) group; there were no positive responders in the LN- (n = 5) group. Data from positive responders are depicted in black, from non-responders in grey. HPV-types other than 16 are depicted in the graph (HPV16-, x; HPV16+, ●) (b) The IFNγ Elispot response upon PD-1 blockade correlated with the percentage of CD8⁺FoxP3⁺CD25⁺ T cells in the tested samples. Only positive responders to HPV16 E6 were included in the analysis. c Activated Treg frequencies (aTregs) and (d) the ratio of CD8⁺FoxP3⁺CD25⁺ T cells: Tregs, both subdivided by responders to anti-PD-1 (i.e., increased HPV16 E6-specific IFNγ response upon PD-1 blockade) and non-responders to anti-PD-1 in HPV16+ LN+ and PT samples (with detectable reactivity to HPV16 E6, same samples as shown in panel b and c). Error bars represent standard error of the mean. **P = 0.001 to 0.01