Use of colony-stimulating factors in the treatment of neutropenia associated with collagen vascular disease.

Chronic neutropenia associated with collagen vascular disease is seen principally with Felty's syndrome complicating rheumatoid arthritis. Multiple recent reports document the efficacy of both granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) in reversing the neutropenia and decreasing the risk of infections in Felty's syndrome. Long-term use of G-CSF appears well tolerated and effective in Felty's syndrome. Of concern, however, have been flares of arthritis and development of leukocytoclastic vasculitis in several patients following the use of colony-stimulating factors (CSFs) in Felty's syndrome. The incidence of these complications of CSF therapy appears to be greater in Felty's syndrome than in other disorders. Future studies will need to address the incidence of these side effects, evaluate strategies to reduce risks, and clarify the optimum use of CFSs in Felty's syndrome.