HRCT-proven leflunomide pneumonitis in a patient with psoriatic arthritis and normal lung function tests and chest radiography.

Egeler RM. Langerhans-cell histiocytosis ‘insight into DC biology’. Trends Immunol 2003;24:190–6. 7 Stoppacciaro A, Ferrarini M, Salmaggi C et al. Immunohistochemical evidence of a cytokine and chemokine network in three patients with Erdheim-Chester disease: implications for pathogenesis. Arthritis Rheum 2006;54:4018–22. 8 Dagna L, Iellem A, Biswas P et al. Skewing of cytotoxic activity and chemokine production, but not of chemokine receptor expression, in human type-1/-2 gamma delta T lymphocytes. Eur J Immunol 2002;32: 2934–43. 9 Tamura K, Kanazawa T, Tsukada S, Kobayashi T, Kawamura M, Morikawa A. Increased serum monocyte chemoattractant protein-1, macrophage inflammatory protein-1beta, and interleukin-8 concentrations in hemophagocytic lymphohistiocytosis. Pediatr Blood Cancer 2008;51:662–8. 10 Yarilina A, Park-Min KH, Antoniv T, Hu X, Ivashkiv LB. TNF activates an IRF1-dependent autocrine loop leading to sustained expression of chemokines and STAT1-dependent type I interferon-response genes. Nat Immunol 2008; 9:378–87.