Infiltrating cells, related cytokines and chemokine receptors in lesional skin of patients with dermatomyositis

BACKGROUND: There have been only two reports on immunophenotypic characterization in the cutaneous lesions of dermatomyositis (DM) that emphasize the importance of the infiltrating CD4+ T lymphocytes. OBJECTIVES: To characterize the immunophenotype of the cells that infiltrate the lesional skin of DM and to evaluate the possible T-helper (Th) polarization Th1/Th2 through detection of specific cytokines, chemokine receptors and markers of cellular activation. METHODS: Skin biopsy specimens derived from pathognomonic lesions (Gottron's papules and Gottron's sign) of eight patients with DM were immunostained with a large panel of monoclonal antibodies to CD3, CD4, CD8, myeloperoxidase (MPO), eosinophil cationic protein, tryptase, CD40, CD40 ligand (CD40L), HLA-DR, interleukin (IL)-2, IL-4, IL-5, IL-13, interferon-gamma, tumour necrosis factor-alpha, receptor 3 for CXC chemokines (CXCR3) and receptor 3 for CC chemokines, using the alkaline phosphatase-antialkaline phosphatase method. Control specimens were obtained from five healthy subjects and from six patients with discoid lupus erythematosus. RESULTS: Activated CD4+ Th lymphocytes (HLA-DR+ CD40L+) were the principal infiltrating cells in the lesional skin of DM; the CD4/CD8 ratio was approximately 2.5. A mixed Th1/Th2 profile and higher Th1 cytokine production together with significant staining for CXCR3 were detected. Neutrophil granulocytes were the second most abundant population; eosinophil granulocytes were very poorly represented. CONCLUSIONS: Activated CD4+ T cells presumably mediate the main pathogenetic mechanisms in pathognomonic skin lesions. The interaction between CD40 and CD40L could be an important mechanism of cellular activation in cutaneous immune-mediated inflammation by induction of secretion of proinflammatory cytokines and chemokines. Neither Th1 nor Th2 clear polarization was found, although there was a slight Th1 prevalence. There was a significant quantity of MPO+ cells (neutrophil granulocytes) in the inflamed tissue, and they might have a role in sustaining the chronic inflammation.