Fig. 1

Characterization of Treg subsets in relation to the response to the influenza vaccine. a-d Frequencies of Treg subsets. e-h Frequencies of Treg subsets expressing the proliferation marker Ki67⁺. A total of 60 subjects, within an age range of 61–98 years old (min-max) and median age of 79 [70–87] (median [IQR]) were included. Comparisons between the groups of vaccine non-responders (n = 33) and responders (n = 27) were made using the nonparametric Mann–Whitney U test. Variables with a p value < 0.05 were considered statistically significant and are shown in bold. *After the Bonferroni correction for multiple comparisons, the comparison of % nTregKi67+ did not remain statistically significant. Note: nTreg, naïve-Treg; and eTreg, effector-Treg