When comparing RA patients and healthy controls, RA patients secreted significantly more IL-10 and TNF in response to citrullinated aggrecan than healthy controls (P < 0.05), and there was a similar trend for IL-17 secretion in response to citrullinated aggrecan (P = 0.065) and citrullinated fibrinogen (P = 0.08). Here, ACAN is linked to rheumatoid arthritis.