Infliximab reduces activated myeloid dendritic cells, different macrophage subsets and CXCR3-positive cells in granuloma annulare.

Disseminated granuloma annulare (GA) is a rare granulomatous dermatitis of unknown etiology. Treatment is often challenging and lack of a uniformly effective treatment, adds to the disease morbidity. Tumor necrosis factor (TNF)-α is an important cytokine in granuloma formation and previous reports have shown improvement of disseminated GA with anti-TNF-α therapy. Nevertheless, the underlying mechanism of actions of TNF-α inhibitors in GA remains unclear. Our aim was to evaluate alterations in the inflammatory infiltrate in a patient who experienced complete clearance of GA after treatment with infliximab. A skin biopsy was obtained before and 24 weeks after treatment with infliximab 5 mg/kg at weeks 0, 2, 6, 14 and 24. Immunohistochemical stains were performed in pre- and post-treatment biopsy specimens using CD1a, CD4, CD8, CD11c, CD32, CD68, CD69, CD163, CD183 and human leukocyte antigen (HLA)-DR to characterize alterations of the infiltrates. Parallel with clinical improvement, we observed a marked decrease in myeloid (CD11c) dendritic cells, different macrophage subsets (CD68, CD32, CD163) and T cells. In addition, a marked reduction of activation markers (HLA-DR, CD69) and CD183+ (CXCR3) cells was observed in post-treatment biopsy specimens. In conclusion, the clinical improvement of disseminated GA by infliximab is paralleled by inhibition of activated myeloid dendritic cells, different macrophage subsets and type 1 T cells.