Figure 2.

Kinetics of commitment to IL-2 gene transcription and TCR down-modulation by naive T cells. CD4 T cells from DO11.IL-2P/GFP Tg mice were cultured with purified splenic DCs and 5 μg/ml OVAp after centrifugation onto the bottom of culture wells. At the indicated times, CD4 T cells were recovered by magnetic sorting after mechanical disruption of the T cell–APC clusters, and were returned to culture without DCs for a total of 20 h. Expression of CD4, transgenic TCR (KJ1–26), and IL-2P/GFP transgene was assessed by flow cytometry. Control cultures were as follows: APC and T cells without OVAp (“No Ag”) and an unseparated culture (OVAp/ “20 h”). Cytometric analyses of cells not recovered by magnetic sorting established that >92% of the total CD4⁺GFP⁺ and >87% of the CD4⁺GFP⁻ T cells were recovered for subsequent culture (see also Fig. S1, available at http://www.jem.org/cgi/content/full/jem.20022230/DC1). Red circles denote contaminating DCs.