Orf-induced immunobullous disease: A distinct autoimmune blistering disorder.
BACKGROUND
Many complications have been reported after orf infection, including lymphadenopathy, secondary bacterial infection, and erythema multiforme. Rare associations with papulovesicular eruptions, including a bullous pemphigoid-like eruption, have also been described.


OBJECTIVE
Our purpose was to clinically, histologically, and immunologically characterize two cases of orf-induced blistering disease, and to determine whether this condition represented a novel disease entity distinct from known immunobullous diseases.


METHODS
Two patients were clinically described and skin biopsy specimens were collected for routine histology, direct immunofluorescence studies, and polymerase chain reaction analysis to detect orf viral DNA. Patients' sera were assessed for autoantibodies by indirect immunofluorescence studies using normal-appearing human salt-split skin, by Western blot analysis using keratinocyte extracts, dermal extracts, and recombinant type VII collagen, and immunoprecipitation studies of extracts from biosynthetically radiolabeled human keratinocytes.


RESULTS
Two distinctive cases of severe, diffuse blistering eruptions after orf infection are described. In one patient, orf virus DNA was detected in the inciting orf lesion, but not in blistered skin, ruling out disseminated orf infection as a cause of the blisters. In both cases, histology revealed subepidermal blisters with mixed inflammatory cell infiltrates containing neutrophils and eosinophils, direct immunofluorescence microscopy studies demonstrated IgG and C3 deposited at the dermoepidermal junctions of perilesional skin, and indirect immunofluorescence studies demonstrated circulating antibasement membrane IgG that bound the dermal side of salt-split skin. Extensive immunoblot and immunoprecipitation studies failed to reveal a consistent, identifiable autoantigen.


CONCLUSIONS
We describe only two cases. The autoantigen recognized by circulating autoantibodies was not identified.


CONCLUSIONS
Orf-induced immunobullous disease is a unique disease entity that is clinically and immunologically distinct from bullous pemphigoid, epidermolysis bullosa acquisita, and other known immunobullous conditions.
White
Kevin P
KP
Department of Dermatology and Dermatopathology, Oregon Health and Science University, Portland, Oregon 97239, USA.
Zedek
Daniel C
DC
White
Wain L
WL
Simpson
Eric L
EL
Hester
Eric
E
Morrison
Lynne
L
Lazarova
Zelmira
Z
Liu
Debra
D
Scagliarini
Alessandra
A
Kurtz
Stephen E
SE
White
Clifton R
CR
Yancey
Kim B
KB
Blauvelt
Andrew
A
D000328:Adult; D001327:Autoimmune Diseases / Q000276:immunology / Q000473:pathology / Q000503:physiopathology* / Q000821:virology*; D001485:Basement Membrane / Q000276:immunology; D003176:Complement C3 / Q000378:metabolism; D004279:DNA, Viral / Q000032:analysis; D004474:Ecthyma, Contagious / Q000150:complications*; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology / Q000378:metabolism; D008297:Male; D008826:Microbial Sensitivity Tests; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D009923:Orf virus / Q000235:genetics; D012867:Skin / Q000378:metabolism / Q000473:pathology*; D012872:Skin Diseases, Vesiculobullous / Q000276:immunology / Q000473:pathology / Q000503:physiopathology* / Q000821:virology*
D003176:Complement C3; D004279:DNA, Viral; D007074:Immunoglobulin G