Objective: To examine the safety and efficacy of granulocyte colony-stimulating factor (G-CSF) alone for the mobilization of peripheral blood progenitor cells in patients with resistant active rheumatoid arthritis (RA).
Methods: Five patients with resistant active RA were studied. A dose of 5 microg/kg of G-CSF (Filgrastim) was given subcutaneously each day for 5 days, and the number of stem cells mobilized into the peripheral blood was assessed by daily CD34 counts. RA disease activity was assessed by standard clinical methods.
Results: The absolute numbers of peripheral blood CD34+ cells peaked on day 4, with a mean value of 0.025 x 10(9)/liter (range 0.013-0.048 x 10(9)/liter). There was no significant change in disease activity during the study or in the month following therapy.
Conclusion: Using G-CSF alone, CD34+ progenitor peripheral blood cells were mobilized in numbers suitable for leukopheresis. G-CSF therapy was well-tolerated in patients with active RA, and was not associated with a flare during treatment or in the month following treatment.