Complete Freund's adjuvant (CFA, 1 mg/ml) is a potent immunoadjuvant that incorporates heat-killed, inactive Mycobacterium tuberculosis bacteria into a paraffin-in-water emulsion. It significantly enhances the immune response of animals to antigens and acts as an inducer of Th1 immune responses and a ligand for TLRs (Toll-like receptors). CFA is effective in stimulating strong and long-lasting immune responses and is commonly used to induce rheumatoid arthritis in rats in experimental models.

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.