2.9. Fluorescence-activated cell sorting (FACS)
Draining lymph node cells were prepared from the lymph nodes of OVA-induced BALB/c mice ground into single cells. To determine the population of IL-4- and IFN-γ-positive cells, draining lymph node cells or BALF cells were stained with APC-conjugated anti-IL-4 antibody, FITC-conjugated anti-IFN-γ antibody, or PE-conjugated anti-CD4 antibody (BD Pharmingen, San Jose, CA, USA) using a Cytofix/Cytoperm kit (BD Biosciences, San Jose, CA, USA) according to the manufacturer’s protocol. In addition, IgE- and IgG1-positive cells were stained with FITC-conjugated anti-IgE antibody or PE-conjugated anti-IgG1 antibody (BD Pharmingen). Stained cells were detected by flow cytometry using the BD LSRFortessaTM cell analyzer (BD Biosciences).