Rheumatoid arthritis: opposing actions of haemopoietic growth factors and slow-acting anti-rheumatic drugs.

The pathogenesis of rheumatoid arthritis and the mode of action of anti-rheumatic drugs are unknown. This hypothesis proposes that haemopoietic growth factors (colony stimulating factors [CSFs]) have an important role in rheumatoid arthritis as regulators of myelopoiesis and as activators of inflammatory leucocytes. It also suggests that slow-acting anti-rheumatic drugs may work by inhibiting myelopoiesis. This opposition to one of the actions of the CSFs would result in fewer inflammatory cells in the inflamed joints.