Passive and active immunizations against interleukin-6 (IL-6) regulate serum levels and skin expression of IL-6. (A, B) In mice challenged by bleomycin, MR16-1 treatment led to a significant increase of IL-6 serum levels (P <0.0001) and a trend for increased IL-6 skin expression (P = 0.08). (C, D) Immunization against the mIS200 peptide conducted to a significant reduction of IL-6 in the serum and in the skin of mice challenged with bleomycin. Bars represent median(Q1,Q3); in total, 36 mice were evaluated for passive immunization and 36 for active immunization. All results are normalized to mice injected with NaCl.