Some epidermolysis bullosa acquisita sera react with epitopes within the triple-helical collagenous domain as indicated by immunoelectron microscopy.
BACKGROUND
Epidermolysis bullosa acquisita (EBA) autoantibodies recognize epitopes predominantly within the N-terminal noncollagenous (NC)-1 domain of type VII collagen. Recently, some EBA cases with reactivity to other domains, i.e. the triple-helical (T-H) collagenous domain and the NC-2 domain, have been reported.


OBJECTIVE
To investigate the ultrastructural localization of epitopes for sera from five patients with EBA that were unreactive by immunoblotting with the NC-1, NC-2 and collagenous domains of type VII collagen.


METHODS
Immunogold postembedding indirect immunoelectron microscopy was performed using normal human skin and type VII collagen-deficient skin as substrates.


RESULTS
Postembedding indirect immunoelectron microscopy revealed that the five EBA sera showed immunoreactivity in the dermis, mainly located 0-400 nm below the lamina densa. IgG labelling was not observed in type VII collagen-deficient skin from a patient with recessive dystrophic epidermolysis bullosa. The distribution histogram found in this study was different from those of sera that reacted with the NC-1 and/or NC-2 domains, and was similar to those of sera reacting with the T-H collagenous domain.


CONCLUSIONS
Our results suggest that epitopes within the T-H collagenous domain of type VII collagen are recognized by IgG antibodies from some EBA sera. These antibodies appear to be found in patients with inflammatory-type EBA.
Ishii
N
N
Department of Dermatology, Kurume University School of Medicine, 67 Asahimachi, Kurume, Fukuoka 830-0011, Japan. norito@med.kurume-u.ac.jp
Yoshida
M
M
Ishida-Yamamoto
A
A
Fritsch
A
A
Elfert
S
S
Bruckner-Tuderman
L
L
Hashimoto
T
T
D000328:Adult; D001323:Autoantibodies; D024143:Collagen Type VII / Q000276:immunology*; D016107:Epidermolysis Bullosa Acquisita / Q000276:immunology*; D018604:Epitope Mapping; D005260:Female; D006801:Humans; D008297:Male; D016253:Microscopy, Immunoelectron
D001323:Autoantibodies; D024143:Collagen Type VII