A pilot study of the effect of oral 8-methoxypsoralen and intraarticular ultraviolet light on rheumatoid synovitis

Objective. To determine the feasibility and safety of combining oral 8-methoxypsoralen (8-MOP) and intraarticular ultraviolet A band light (WA) to treat rheumatoid synovitis, and to demonstrate a favorable biological effect. Methods. Six patients with rheumatoid arthritis (RA) and clinically evident knee synovitis were given a single oral dose of and MOP (0.6 mg/kg) followed by arthroscopy with a UVA laser equipped small arthroscope. Nine tissue samples treated with UVA doses ranging from 4 to 52 J/cm² were examined by light microscopy and by immunohistochemistry for vascular cell adhesion molecule I (VACM-1), intracellular adhesion molecule 1 (ICAM-1), E-selectin and HLA-DR expression. Results, No reduction in inflammation was evident on light microscopy, nor was there any evidence of tissue injury on gross inspection or light microscopy. At 28 and 52 J/cm², VCAM-1, ICAM-1 and E-selectin staining were reduced in the posttreatment synovial biopsies. No local or systemic complications were observed by Day 30 in any patient. Conclusion. This treatment modality appears to be feasible and safe and may potentially be useful in the treatment of the synovitis associated with RA.