Table 1. In vivo experience correlates with ex vivo development of resistance to IL-4.

DBA mice were immunized with cII/CFA and spleens were collected after one, two, four or six weeks. Spleen cells were re-stimulated with collagen and IL-4 was added on day zero, one or three of culture. IL-17 was measured by ELISA on day five. A designation of resistance required that IL-17 production in the presence of IL-4 was at least 70% of IL-17 production in the absence of IL-4. Spleens from one week immunized mice continued to respond to IL-4 when it was added after three days of culture, while spleens from six week immunized mice failed to respond when IL-4 was added on day zero or one.

Weeks since immunization	Days culture until IL-4 resistance
1	>3
2	2
4	1
6	0–1