Fig. 1. Neonatal CD4+ cells that have undergone homeostatic proliferation rapidly produce both Th1 and Th2 cytokines.
Lymph node cells from 7 day old BALB/c mice were stained with anti-CD4 and anti-CD44 and sorted into CD4+CD44hi and CD4+CD44lo populations. The sorted cells were stimulated with anti-CD3 and anti-CD28 for the indicated times, supernatants were collected, and the amounts of IFNγ and IL-4 were measured by specific ELISA. Each symbol represents an independent experiment.