Figure 2

The effector function of cytokine-stimulated lymphocytes resides within the CD4⁺ population. (a) Effector function of the CD4⁺ cytokine-activated T (Tck) cell population compared with that of the CD4^- Tck population. Lymphocytes were positively separated using CD4⁺ magnetic beads (Dynal) before stimulation for 8 days with IL-2, IL-6 and tumour necrosis factor (TNF)-α. On day 8 lymphocytes were co-cultured with autologous monocytes (at the indicated ratios) for 18 hours before supernatants were removed and assayed for TNF-α by ELISA. Supernatants from cultures of monocytes and T cells alone as negative controls contained under 50 pg/ml. This experiment is representative of seven different donors. ***P < 0.001 comparing CD4⁺ versus CD4^- at a ratio of 3:1, or comparing CD4⁺ versus CD4^- at a ratio of 5:1 using one-way analysis of variance (ANOVA) with Bonferroni's multiple comparison. Because of limited CD4^- cell numbers, a comparison at a ratio of 7:1 of could not be performed in this experiment. (b) Effector function of CD8⁺ Tck population compared with that of CD8^- Tck population. Lymphocytes were positively separated using CD8⁺ magnetic beads (Dynal) before stimulation for 8 days with IL-2, IL-6 and TNF-α. On day 8 lymphocytes were co-cultured with autologous monocytes (at the indicated ratios) for 18 hours before the supernatants were removed and assayed for TNF-α by ELISA. Supernatants from cultures of monocytes and T cells alone as negative controls contained under 50 pg/ml. This experiment is representative of seven different donors. ***P < 0.001 comparing CD8⁺ versus CD8^- at a ratio of 5:1, or comparing CD8⁺ at versus CD8^- at a ratio of 7:1 using one-way ANOVA with Bonferroni's multiple comparison.