CXCL1 and Arthritis: To further assess the severity of arthritis, we measured the mRNA levels of a variety of pro-inflammatory cytokines and chemokines, including Il18bp, Il18, Il1b, Il6, Il1r2, Ifng, Cxcl9, Cxcl1, and Cxcl2 in arthritic joints of IL-18BP KO and WT littermates.