Complete Freund's Adjuvant (CFA) Model

Complete Freund’s Adjuvant (CFA) is a water-in-oil emulsion containing heat-killed mycobacterial components. Its adjuvant activity results from sustained antigen release at the injection site, triggering a local innate immune response and an intense, pain-associated inflammatory reaction.

Intraplantar injection of CFA in mice and rats produces an acute inflammatory response associated with non-evoked pain that can persist for several days. In Transpharmation’s model, weight bearing is measured post-CFA injection to reveal analgesic potency.

Compounds can be tested acutely (day 1 post-CFA) or over a longer time course, the latter more closely reflecting the pathophysiology of chronic inflammatory conditions such as rheumatoid arthritis or osteoarthritis. This flexibility makes the CFA model a versatile, well-validated tool for screening novel analgesic and anti-inflammatory candidates across both acute and chronic inflammatory pain indications.

CFA model summary: intraplantar CFA in mouse (20 µL of 1.5 mg/mL) and rat (100 µL of 1 mg/mL), weight-bearing readout, NSAID positive controls, N of 10 to 12. Bar charts of weight bearing (ipsilateral/contralateral %): in mice, indomethacin 10 mg/kg restores weight bearing at 1, 3 and 8 hours; in rats, ibuprofen, celecoxib, naproxen and indomethacin restore it from 1 to 48 hours.
Validation Data: Timecourse of paw edema, tactile allodynia and histology following intra-plantar injection of Freunds adjuvant.
Paw scans 30 days after FCA injection: bone erosion and cartilage loss in some animals Tactile allodynia after intra-plantar FCA: von Frey withdrawal thresholds over 30 days Time course of paw edema after intra-plantar FCA, measured over 30 days

Rats were injected intra-plantar with Freunds adjuvant (0.5-1mg/ml, 50uL volume) and paw volume measured over 30 days. At 30 day (but not 1 day), some evidence of bone erosion (*) and cartilage loss (#) was evident in some animals.