Figure 3.

Instruction for IL-4 expression after primary activation of Th lymphocytes. Naive CD62L⁺CD4⁺ OVA-TCR^tg/tg cells were either directly stimulated with PMA/ionomycin or they were labeled with CFSE and activated for 17 or 42 h with OVA_323–339 and APCs in the presence of IL-4, anti–IL-12, and anti–IFN-γ before PMA/ionomycin recall. Intracellular IL-4 and IL-2 expression were examined among OVA-TCR⁺ cells. The specificity of the intracellular IL-4 staining was controlled by blocking the digoxigenized anti–IL-4 detection mAb with an excess of the unconjugated anti–IL-4 mAb. Indicated frequencies of IL-2–producing cells have been corrected for the background frequencies of the respective control stainings.