Complete Freund's adjuvant (CFA) is an immunologic adjuvant emulsified with antigens, composed of heat-killed, inactivated Mycobacterium tuberculosis in a water-in-oil emulsion with paraffin oil. As a TLR ligand, it enhances the immune response to antigens in animals, induces Th1-type immune responses, and is commonly used to establish experimental models such as rheumatoid arthritis, persistent inflammatory pain, and experimental autoimmune myocarditis (EAM) in rats.

Complete Freund's adjuvant, administered subcutaneously (s.c.) at a dosage of 1 mg/ml and 0.1 mL (皮下注射;每天一次,持续两天), has been used to induce rheumatoid arthritis in Sprague-Dawley rats. In this animal model [3], the treatment was applied once daily for two consecutive days. The outcomes demonstrated a rise in the indexes of the thymus and spleen. There was a reduction in the activities of GSH, CAT, SOD, and MPO. Furthermore, the levels of IL-1β, IL-6, IL-17, MCP-1, TNF-α, COX-2, 5-LOX, NF-p65, IgG1, and IgG2a were increased, while the level of IL-10 was decreased.