Inhibition of neutrophil migration soon after initiation of treatment with leflunomide or methotrexate in patients with rheumatoid arthritis: findings in a prospective, randomized, double-blind clinical trial in fifteen patients - Kraan, M C; de Koster, B M; Elferink, J G; Post, W J; Breedveld, F C; Tak, P P (Arthritis Rheum, 2000)