Figure 5. The cutaneous immune system primes Th17 cells in an IL-6-dependent manner.

(A) CD4⁺ T cells from the inguinal, popliteal, brachial, and axillary lymph nodes of WT and Il6^−/− mice were stimulated with plate-bound anti-CD3 and anti-CD28 for 48 hours and cytokine production was assayed in the culture supernatants. (B) 2.5−10⁶ purified CD45.1 congenic OT-II T cells were transferred intravenously into WT or Il6^−/− mice (CD45.2 background). The recipients were then immunized in the footpads with 50µg/fp of OVA and 5µg/fp of LPS emulsified in IFA. CD4⁺ T cells were enriched by negative selection from the draining lymph nodes on day 5 post-immunization, and CD4⁺CD45.1⁺ OT-II T cells were recovered by cell sorting followed by stimulation with plate-bound anti-CD3 and anti-CD28 for 48 hours. Cytokine secretion was analyzed by ELISA in the culture supernatants. Data are representative of two independent experiments. Bar graphs represent mean ± SEM.