Immunoelectron microscopy study of superficial skin nerves in drug-induced acute urticaria.
BACKGROUND
Few studies have evaluated the ultrastructure of the superficial skin nerves in urticaria.


OBJECTIVE
The objective of this study was to describe findings in superficial skin nerves in cases of drug-induced acute urticaria.


METHODS
Seven patients with drug-induced acute urticaria were included in the study. Skin biopsies were obtained from the urticarial lesion and from the apparently normal skin. The 14 fragments collected were processed for immunogold electron microscopy using single stains for antitryptase and anti-FXIIIa antibodies, as well as double immunogold labeling for both.


RESULTS
Some sections showed mast cells in the process of degranulation. Following double immunogold staining, 10 nm (FXIIIa) and 15 nm (Tryptase) gold particles were found together throughout the granules in mast cells, indicating that tryptase and FXIIIa are located inside each one of the granules of these cells. Interestingly, we found strong evidence of the presence of tryptase and factor XIIIa in the superficial skin nerves of these patients, both in cases of urticarial lesions (wheals) and in the apparently normal skin.


CONCLUSIONS
Tryptase and FXIIIa are present in the superficial nerves of the skin in drug-induced acute urticaria. This is the first report of tryptase and FXIIIa expression in the superficial skin nerves of patients with urticaria. Tryptase may be participating in neural activation in these patients, while FXIIIa may be present in the nerves to guarantee the functional integrity of structures.
Dermatology Department, School of Medicine, São Paulo University, Brazil. prcriado@uol.com.br
Paulo Ricardo
PR
Criado
Roberta Fachini Jardim
RF
Criado
Cleusa F H
CF
Takakura
Carla
C
Pagliari
Mirian Nacagami
MN
Sotto
Cidia
C
Vasconcellos
D000328:Adult; D004342:Drug Hypersensitivity / Q000276:immunology / Q000473:pathology*; D026122:Factor XIIIa / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D010525:Peripheral Nerves / Q000648:ultrastructure; D012867:Skin / Q000201:enzymology / Q000294:innervation*; D053802:Tryptases / Q000378:metabolism; D014581:Urticaria / Q000139:chemically induced / Q000276:immunology / Q000473:pathology*
D026122:Factor XIIIa; D053802:Tryptases