Imaging rheumatoid arthritis specifically with technetium 99m CD4-specific (T-helper lymphocytes) antibodies

CD₄ expressing T-lymphocytes are involved in the pathogenesis of rheumatoid arthritis, so the possibility of using radiolabelled CD₄-specific antibodies to localise diseased joints was studied. Prospectively six patients with rheumatoid arthritis were investigated. Five of them received 200–300 g of a 555 MBq technetium 99m CD₄-specific antibody (MAX.16H5) and were examined with three phase bone scans. Max.16H5 (IgG1) was labelled according to the mercaptoethanol (Schwarz) method. Lymphocytes of one patient were isolated on a Ficoll-Hypaque gradient and labelled with the antibody in vitro. Scans were performed 1.5 h, 4 and 24 h post injection in anterior and posterior views. In all patients, diseased joints could be clearly imaged at as early as 1.5 h. The localisation of the diseased joints correlated (P<0.01) with the clinical signs, with the early methylene diphosphonate (MDP) scan (P > 0.01) and only weakly with the late bone scan (P > 0.05). According to these data we conclude that^99mTc-labelled CD₄-specific antibodies specifically image actively diseased joints in rheumatoid arthritis.Supported by the Johannes und Frieda Marohn-Stiftung at the University of Erlangen-Nürnberg