Figure 2.

IL-4-induced long-term CD8⁺ T cell survival in alloantigen-, anti-CD3-, and PMA + ionomycin-induced activation systems. Naive CD8⁺ T cells were activated in the presence of indicated cytokines and transferred into B10.TL congenic hosts, and donor/total CD8⁺ T cell ratios were determined as in Fig. 1. Donor CD8⁺ T cells were 2C naive CD8⁺ T cells activated by B10.A B cell blasts (a), 2C naive CD8⁺ T cells activated by B10 macrophages + 0.5 μg/ml SL8 (SIYRYYGL) peptide (b), B10 naive CD8⁺ T cells activated by PMA + ionomycin without added accessory cells (c); B10 naive CD8⁺ T cells activated by anti-CD3 mAb + syngeneic peritoneal macrophages (d), or B10 naive CD8⁺ T cells activated by combined anti-CD3/anti-CD28 mAbs + syngeneic B cell blasts (e). Donor cells identified by F-anti-Thy-1.2 were 98% CD8⁺, except for PMA + ionomycin-activated donor CD8⁺ T cells, most of which had lost CD8 expression (23) but remained Thy-1.2⁺. In this case, Thy-1.2⁺ alone was used as the criteria to score cells of donor origin. The number of cells transferred into each B10.TL host was 5 × 10⁶ for a, c, d, and e and 6 × 10⁶ for b. B10.TL recipients were unirradiated for b, c, d, and e and 400R-irradiated for a.