IL-1RI⁺ memory CD4⁺ T cells are committed to produce IL-17 even before TCR triggering. (A) RT-PCR analysis of IL17, RORC, and IRF4 expression in sorted and unstimulated (resting) IL-1RI⁺ and IL-1RI⁻ memory CD4⁺ T cells. RT-PCR results are relative to the number of transcripts encoding β-actin. Data represent the mean ± SEM of 5 donors. (B-D) Flow cytometric analysis of CCR4, CCR6, IL-23R, IL-21R, and CD161 expression on IL-1RI⁺ and IL-1RI⁻ memory CD4⁺ T cells. Representative data from 10 (B-C), or 4 (D) separate experiments (1 experiment per donor).