Figure 1.

Stability of cytokine phenotype of primed CD4⁺ T cells. CD4⁺ cells from B10.A TG mice were primed twice in vitro with cytochrome C peptide, APC, IL-2, and anti-IL-4 and IL-12 (T_H1 cells) or IL-4 (T_H2 cells). After the second priming culture, a portion of the cells were stimulated, and the number of cells containing cytosolic IL-4 and IFN-γ was determined and the secretion of the two cytokines was measured. The twice-primed cells (3 × 10⁷) were also transferred into B10.A mice. Four weeks later, CD4⁺ T cells were purified from spleens and lymph nodes of the recipient mice and restimulated with peptide, APC, and IL-2, and with anti-IL-4 and IL-12 or IL-4. After 5 days, the cells (10⁶) were challenged with peptide, APC, and IL-2. IL-4 and IFN-γ production were measured.