Arthritis and joint inflammation is suppressed in subcutaneous immunized IL-23p19−/−mice. Arthritis severity and incidence over time after immunization of wild type (WT) BALB/c, p40−/− and p19−/− mice either by (A) intraperitoneal (i.p.) or (B) intradermal/subcutaneous (i.d./s.c.) route three times with rG1 in dimethyldioctadecyl ammonium bromide. Data represent mean ± standard error of the mean (SEM, n =11 to 12 mice) and are representative of three independent experiments. *P <0.05. Representative images of ankle joints of (C) WT and IL-12p40−/− i.p. immunized mice and (D) WT and IL-23p19−/− s.c. immunized mice. Ankle joints were dissected, fixed in formalin, decalcified, embedded in paraffin and stained with haemotoxylin and eosin. (E) Proliferation of spleen and inguinal lymph node (LN) from WT, p40−/− and p19−/− mice. Spleen and inguinal LN were harvested from immunized mice at approximately 70 days. Cells were restimulated in vitro with rG1 for 4 days and proliferation measured as the incorporation of 3H-thymidine (n =11 to 12). (F) G1-specific IgG2a antibody and (G) G1-specific IgG1 were measured in sera by enzyme-linked immunosorbent assay (n =4 to 5). Data represent mean ± SEM. *P <0.05. IL, interleukin.