Multiplex serum cytokine profile of Rag2^−/− mice receiving PBS, IL-4 (1 μg/hour), or IL-13 (1 μg/hour) via micro-osmotic pump for 3 days. Serum cytokine concentrations in B6 Rag2^−/− mice treated 3 days earlier with an IL-4– or IL-13–containing mini-pump. Three to 5 mice were used per group, and similar results were obtained in a second similar experiment. *P < .05.