Immunological actions of cyclosporin A in rheumatoid arthritis.

Rheumatoid arthritis is present in a population which is heterogeneous both clinically and immunologically. A variety of cells including lymphocytes, macrophages and fibroblasts play important roles in its pathogenesis, but the T cell appears to be a common thread throughout the disease process. Treatments aimed at reducing these lymphocytes mechanically and specifically result in a good clinical response in many patients. The mechanism of action of cyclosporin A (CyA) in inhibiting T lymphocytes presents a more specific form of therapy. Though limited, studies including immune profiling suggest that certain subgroups of RA patients are more likely to respond to CyA. Further studies are required to test these findings, but targetted therapy with CyA could result in enhanced and longer-lasting efficacy.