Imaging of RA Inflamed Joints with 99mTc-Labeled Specific Murine Anti-CD4- and Nonspecific Human Immunoglobulin

Abstract

The presence of CD4-molecules on T-helper cells and macrophages, both abundantly present in human rheumatoid arthritis (RA) inflammatory infiltrates, provides the rationale for the use of radiolabeled anti-CD4 monoclonal antibodies (mAbs) to image RA arthritic joints (Becker et al. 1990). The imaging properties of a 99mTechnetium (99mTc)-labeled murine anti-human CD4 mAb (MAX.16H5; 200-300 μg, 370-550 MBq) were compared to those of polyclonal human immunoglobulin (HIG; Technescan^R, MDH-67, Mallinckrodt Diagnostica; 1 mg, 370 MBq) after intravenous injection into 8 patients with severe, active RA; in one RA patient the anti-human CD4 mAb was compared to an isotype-matched murine control mAb (BW 431/26; anti-human carcino-embryonic-antigen; Behringwerke; 2 mg; 810 MBq), and to HIG on separate occasions. Whole body and joint scans in anterior and posterior views were obtained 1, 4 and 24 h after injection.

As early as 4 h after injection, the anti-human CD4 mAb showed a higher target-to-background ratio in arthritic knee and elbow joints in comparison to either polyclonal HIG or, in one case, the murine isotype matched control mAb. Specific detection of inflammatory infiltrates rich in CD4⁺ cells may allow a superior quality in the imaging of RA inflamed joints.