Efficient induction of collagen arthritis by the use of a synthetic muramyl dipeptide.

We developed an efficient method for production of experimental polyarthritis. Native collagen (type II) from human costal cartilage was emulsified with incomplete Freund's adjuvant (IFA) containing the synthetic adjuvant N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP), and injected into one hind footpad of the PVG/c rat. This method reproducibly induced severe arthritis with high incidence, whereas the collagen alone in IFA produced mild arthritis with low incidence. MDP alone in IFA was shown to be minimally arthritogenic under identical conditions.