The RA⁺CCR7^–27⁺ T-cell subset contains reduced but detectable TREC levels and expresses genes associated with effector functions. (A) Real-time PCR quantification of TRECs was performed on sorted RA⁺CCR7⁺27⁺ (N), RA⁺CCR7^–27⁺ (?), and RA⁺CCR7^–27^– (E) CD8⁺ T subsets from 8 healthy young individuals (age range, 20-36 years). Asterisk indicates not detectable (sorted cell number was 5 × 10⁴ to 10⁵, lower quantification limit = 0.01%-0.02%). (B) Gene expression analysis was performed on sorted N, (?), and E CD8⁺ T cells using a modified RT-PCR protocol (see “Materials and methods”). Data from 10 independent 5-cell aliquots as well as negative (–) and positive (+) controls are depicted. Comparable results were obtained in 5 healthy individuals.