TNF and arthritic joint disease: In the case of collagen-induced arthritis (CIA), the antigen is cartilaginous type II collagen, which stimulates a substantial inflammatory response involving IL-17, TNF-α, and IL-1β.216 In the K/BxN serum-transfer arthritis (K/BxN STA) model, antibodies to glucose-6-phosphate isomerase are generated in a susceptible host and then transferred via serum injections to experimental mice.