Expression of effector mediators in pE₁ and pE₂ T cells. (A) Gene expression analysis was performed on sorted RA⁺CCR7⁺27⁺28⁺ (N), RA⁺CCR7^–27⁺28⁺ (pE₁), RA⁺CCR7^–27⁺28^– (pE₂), and RA⁺CCR7^–27^–28^– (E) CD8⁺ T cells by RT-PCR. The same set of primers as described in Figure 2B was used. Data from 6 or 8 independent 5-cell aliquots are shown. These results are representative of 2 healthy individuals; (–), negative; (+), positive controls. (B) The proportion of granzyme B–positive or perforin-positive cells among N (27⁺), pE₁ (28⁺), pE (27⁺), pE₂ + E (28^–), and E (27^–) T cells was determined by immunofluorescence. The pE population includes pE₁ (27⁺28⁺) and pE₂ (27⁺28^–) T cells. Note that the perforin signal is considerably lower in pE than in E cells. (C) Ex vivo–sorted CD8⁺,N,pE₁,pE₂, and E T cells were tested in a redirected cytolytic assay against ⁵¹Cr-labeled P815 target cells. The pE and E subsets were unable to lyse P815 cells in the absence of CD3 mAbs (lysis ≥ 2%, data not shown). Data are representative of 2 healthy donors.