To enrich for cells with the Th1 or Th2 phenotypes, after 14 days priming, Th1 and Th2 cells were stimulated with platebound anti-CD3+ anti-CD28 for 8 hours. IFNc+ Th1 cells and IL-5+ Th2 cells were stained and sorted by the MACS cytokine secretion assay (Miltenyi Biotec, Auburn, CA) according to the manufacturer's instructions. The enriched IFNc+ Th1 cells and IL-5+ Th2 cells were expanded as previously for 14 days.