Analysis of the expansion of regulatory T cells following immunization. A. Representative examples (top panels) of the frequency of CD25highFOXP3+ on viable CD3+CD4+ T cells in patients from the IMP321 or no IMP321 groups. Bottom panels show the expression of CD45RO and CD127 on viable CD3+CD4+CD25highFOXP3+ regulatory T cells in a representative patient from the IMP321 group. B. Cumulative analysis of the expansion of CD25highFOXP3+ CD4+ T in patients from the IMP321 or no IMP321 groups. The star (+) indicates a significant difference using a two-tailed unpaired student t test. C. Correlation between the relative expansion of MART-1-specific CD8 T cells and of CD4+CD25highFOXP3+ regulatory T cells (R2 = 0.11; P < 0.05).