title: A study of dendritic cell and MHC class II expression in dogs with immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis.
abstract: The term immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis (ImR-LPP) has previously been proposed to denote a sub-population of dogs with idiopathic pododermatitis. The objective of this study was to investigate dendritic cell (DC) and MHC class II antigen expression in lesional skin of dogs with ImR-LPP (n=47). Median epidermal CD1c(+) cell counts were 37.8 and 12.5 mm(-1) in ImR-LPP dogs and healthy controls (n=27), respectively (P<0.01), while the corresponding dermal cell counts were 180.9 and 45.0 mm(-2), respectively (P<0.01). Intra-epidermal clusters of DCs were observed in 18/47 dogs with ImR-LPP. Median epidermal MHC class II(+) cell counts were 32.5 and 10.5 mm(-1) in ImR-LPP dogs and healthy controls, respectively (P<0.01), while the corresponding dermal cell counts were 216.9 and 46.9 mm(-2), respectively (P<0.01). Dermal MHC class II(+) staining was primarily associated with DCs (47/47 dogs), mononuclear inflammatory cells (45/47), fibroblast-like cells (19/47) and vascular endothelium (14/47). The DC hyperplasia and increased MHC class II expression in lesional ImR-LPP skin are consistent with enhanced antigen presentation, and suggest that both parameters may contribute to the pathogenesis of ImR-LPP through the priming and activation of CD4(+) T cells. Equally, it is possible that the enhanced DC numbers observed in this study may contribute to the immunoregulation of steady-state pathology in lesional ImR-LPP skin through additional expanded, although as yet unresolved, mechanisms.
authors.affiliation: School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Dublin 4, Ireland. rory.breathnach@ucd.ie
authors.forename: Rory M
authors.initials: RM
authors.lastname: Breathnach
authors.forename: Shay
authors.initials: S
authors.lastname: Fanning
authors.forename: Grace
authors.initials: G
authors.lastname: Mulcahy
authors.forename: Hugh F
authors.initials: HF
authors.lastname: Bassett
authors.forename: Boyd R
authors.initials: BR
authors.lastname: Jones
mesh_terms: D000818:Animals; D016022:Case-Control Studies; D016207:Cytokines / Q000096:biosynthesis; D003872:Dermatitis / Q000276:immunology / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D004283:Dog Diseases / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D004285:Dogs; D005260:Female; D005534:Foot Diseases / Q000276:immunology / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D005786:Gene Expression Regulation; D005802:Genes, MHC Class II / Q000235:genetics / Q000276:immunology; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D012867:Skin / Q000276:immunology / Q000473:pathology; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology