In vitro functional assay of CD4⁺ and CD8⁺ T cells expressing CCR6. Freshly isolated peripheral blood lymphocytes (PBLs) of UI individuals were stimulated with anti-CD2, anti-CD3, and anti-CD28 antibodies (A) and 15mer EBV pool of peptides (B) for 12 hours in the presence of brefeldin A for cytokine production assay (see “Patients, materials, and methods”). CD4⁺ T cells and CD8⁺ T cells were then analyzed by flow cytometric analysis as a function of CCR6 expression for their production of IFN-γ, IL-2, and TNF-α in the 2 memory subsets defined as T_CM (CD45RA⁻/CCR7⁺) and T_EM (CD45RA⁻/CCR7⁻). Results are shown as the percentage of cytokine secreting CD4⁺ or CD8⁺ T cells expressing or not CCR6 and represent 5 independent experiments. *P < .05 **P < .01. Error bars represent the standard error of the mean.