In autoimmune diseases like rheumatoid arthritis, structural variations in IL-12 family cytokines (e.g., IL-23-driven IL-17 cascade) disrupt the immune balance, affecting leukocyte migration, bone erosion, and angiogenesis, while IL-12, IL-27, and IL-35 exert counter-regulatory effects (100). Here, IL27 is linked to rheumatoid arthritis.