Intracellular cytokine staining.
T cells were stimulated with 2 x 10-7 M PMA and 1 mug/ml of ionomycin (Sigma Chemicals) for 4 h. The following mAb was used: anti-IL-4-PE (8D4-8, BD). Matched isotype controls were used at the same protein concentration as the respective antibodies. Four-color FACS was performed using an EPICS XL-MCL (Beckman Coulter) using the software Expo32 version for data acquisition and evaluation. 
