An anti-CD4 antibody for treatment of chronic inflammatory arthritis.

Monoclonal antibodies (mAb) to the CD4 surface molecule inhibit the function of CD4+ T cells in vitro and have been used for treatment of autoimmune diseases in several animal models. Recently, an anti-CD4 mAb has been described that improved the clinical situation of rheumatoid arthritis (RA) patients although no change in laboratory parameters could be observed. Here, we report on a different high-affinity anti-CD4 mAb (MAX.16H5) and its use for treatment of RA. Reduction of the Ritchie index, morning stiffness and the number of swollen joints demonstrated the clinical benefits of the therapy. In addition, laboratory parameters like ESR, CRP, and rheumatoid factor were reduced in 6/12 treatments. A rapid depletion of CD4+ T cells was observed in all patients which reached a minimum 1 hour after administration. However, efficacy of treatment did not correlate with T cell depletion. The antibody accumulates at the site of inflamed joints as detected by 99m-Tc-labelling. Affected digital joints were detected earlier by virtue of helper T cell imaging than by conventional bone scans.