IL1RL2 and Arthritis: Interestingly, experimental studies of collagen-induced arthritis (CIA), antigen-induced arthritis, TNF-induced arthritis, and K/BxN serum transfer-induced arthritis of mice show that IL-36 (α, β, and γ) and IL-36R are present, but blockade of IL-36R or IL-36R–/– mice led to no improvement in arthritis.