Macrophage targeting with 99mTc-labelled J001 for scintigraphy of joint inflammation in ovalbumin-induced arthritis in rabbits.

Background and Objective: J001 scintigraphy is a new approach, based on macrophage targeting, developed for tumor and inflammation imaging. J001, a non-pyrogenic acylated poly(1,3)galactoside purified from the membrane of a non-encapsulated strain of Klebsiella pneumoniae associates selectively with macrophages via binding to CD11b and CD14 molecules. Since macrophages play a primary role in inflammatory arthritis processes, J001 labeled with 99mTc appeared to be of interest for the scintigraphic imaging of inflammatory lesions. The purpose of this study was to assess the potential of J001 scintigraphy for imaging inflammatory arthritis in the model of ovalbumin-induced arthritis in rabbits.
Material and Methods: Ovalbumin-induced arthritis was developed in 17 rabbits. 99mTc-J001 scintigraphy was performed 4 weeks after arthritis induction in 17 rabbits and was repeated at 6 and 8 weeks in 8 rabbits. 99mTc-J001 and 99mTc-MDP scintigraphy were performed before and 2.5 months after radionuclide synovectomy with the intra-articular injection of a high energy beta-emitting radionuclide (186Re) in 3 rabbits and 186Re (first subjected to a complete decrease of radioactivity) in 3 rabbits.
Results: 99mTc-J001 scintigraphy was able to image inflammatory arthritis 4 weeks after induction. J001 scintigraphy demonstrated an increased uptake earlier than MDP, which was maintained at week 8. After radionuclide synovectomy, a clear decrease in the J001 scintigraphy ratio occurred, whereas the MDP scintigraphy ratio was stable. After the intra-articular injection of inactive 186Re, no changes in MDP and J001 scintigraphy ratio appeared.
Conclusion: 99mTc-J001 scintigraphy is able to image joint inflammation and to assess the response to anti-inflammatory treatment in an experimental model of arthritis.