Cytokine expression in human cutaneous chronic graft-versus-host disease

Although chronic graft-versus-host disease (GVHD) remains a frequent complication of bone marrow transplantation (BMT), the pathogenesis remains unclear. We examined the potential role of cytokines in mediating chronic GVHD. Skin samples from seven patients with cutaneous chronic GVHD, six post-BMT controls and six normal controls were evaluated by reverse transcription polymerase chain reaction for the proinflammatory cytokines interleukin-1α (IL-1α) and tumor necrosis factor-α (TNF-α), Th1-associated cytokines IL-2 and interferon-γ (IFN-γ), Th2-associated cytokines IL-4, IL-5 and IL-10, and fibrosis-associated cytokines platelet derived growth factor (PDGF) and transforming growth factor-β (TGF-β). IFN-γ transcription was significantly more frequent in cutaneous chronic GVHD (86%) vs post-BMT and normal controls (17% (P = 0.03) and 0 (P = 0.005), respectively). IL-2 transcription was more frequent in chronic GVHD (28%) and post-BMT controls (50%) vs normal controls (17%). TNF-α mRNA was frequent in chronic GVHD (71%) and post-BMT controls (83%), but not significantly more than in normal controls (50%). Transcription of IL-1α, IL-4, IL-5 and IL-10 was infrequent in all three groups. PDGF and TGF-β mRNA were detected in the majority of all samples. The frequent transcription of IFN-γ in cutaneous chronic GVHD supports its potential role in mediating the associated tissue injury. While the cellular sources of these cytokines are uncertain, their expression and secretion in situ may propagate the cytotoxic cascade and perpetuate the tissue injury. Better understanding of the contribution of IFN-γ and other cytokines to the pathogenesis of chronic GVHD may allow the design of more specific and more effective therapy.