MACROPHAGE TARGETING WITH TC-99M-LABELED J001 FOR SCINTIGRAPHY OF JOINT INFLAMMATION IN OVALBUMIN-INDUCED ARTHRITIS IN RABBITS

Background and objective: J001 scintigraphy is a new approach, based o n 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 associa tes selectively with macrophages via binding to CD11b and CD14 molecul es. Since macrophages play a primary role in inflammatory arthritis pr ocesses, J001 labeled with Tc-99m appeared to be of interest for the s cintigraphic imaging of inflammatory lesions. The purpose of this stud y was to assess the potential of J001 scintigraphy for imaging inflamm atory arthritis in the model of ovalbumin-induced arthritis in rabbits . Material and methods: Ovalbumin-induced arthritis was developed in 1 7 rabbits. Tc-99m-J001 scintigraphy was performed 4 weeks after arthri tis induction in 17 rabbits and was repeated at 6 and 8 weeks in 8 rab bits. Tc-99m-J001 and Tc-99m-MDP scintigraphy were performed before an d 2.5 months after radionuclide synovectomy with the intra-articular i njection of a high energy beta-emitting radionuclide (Re-186) in 3 rab bits and Re-186 (first subjected to a complete decrease of radioactivi ty) in 3 rabbits. Results: Tc-99m-J001 scintigraphy was able to image inflammatory arthritis 4 weeks after induction. J001 scintigraphy demo nstrated 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 st able. After the intraarticular injection of inactive Re-186, no change s in MDP and J001 scintigraphy ratio appeared. Conclusion: Tc-99m-J001 scintigraphy is able to image joint inflammation and to assess the re sponse to anti-inflammatory treatment in an experimental model of arth ritis.