CD45RC^high and CD45RC^low CD8 T cells produce different cytokine profiles. (A) CD8 T cells were purified from spleen and lymph nodes of naive LEW rats after depletion of CD4⁺, TCRγδ T cells, B cells, monocytes, and natural killer (NK) cells. The purified CD8 T cells (top panel) were further fractionated by anti-FITC and anti-PE magnetic beads on the basis of their expression of CD45RC using FITC-conjugated OX22 and of their expression of TCR using PE-conjugated R73. The values represent the purity of each cell population. (B-F) Highly purified CD45RC^high and CD45RC^low CD8 T cells (5 × 10⁵/well) from LEW rats were stimulated in vitro in mixed lymphocyte reaction using irradiated, T-cell-depleted, allogeneic BN spleen cells (2.5 × 10⁵ cells/well) as stimulators in the presence of exogenous rat IL-2 (10 U/mL). Proliferation was assessed with an 18-hour (³H)-thymidine pulse added after 96 hours of culture. Tissue culture supernatants collected 96 hours after stimulation were assayed for IFNγ (C) and IL-10 (D) protein levels using capture ELISA. IL-4 (E) and IL-13 (F) mRNA expression were assayed by quantitative RT-PCR following stimulation for 72 hours. Results are expressed as arbitrary units (AU), representing the ratio between cytokine and HPRT mRNA × 100. The data shown represent the quantification made from a pool of triplicate cultures and are representative of 3 independent experiments.