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

Abstract

Objective: To determine the feasibility and safety of combining oral 8-methoxypsoralen (8-MOP) and intraarticular ultraviolet A band light (UVA) 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 8-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 1 (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.