No activation of urokinase plasminogen activator by anti-desmoglein 3 monoclonal IgG antibodies in cultured human keratinocytes.
BACKGROUND
Although pemphigus vulgaris (PV)-IgG has been shown to activate urokinase plasminogen activator (uPA) in cultured keratinocytes, activation of uPA is thought to have no primary role in PV-acantholysis, because PV-IgG is still pathogenic in uPA- and tissue-PA-knockout mice.


OBJECTIVE
To determine if PV-IgG-induced uPA activation is due to specific antibody against Dsg3, we examined whether or not pathogenic monoclonal anti-Dsg3 antibody can activate uPA, because PV-IgG is thought to contain antibodies against unknown antigens besides Dsg3.


METHODS
We stimulated cultured normal human and DJM-1 keratinocytes with monoclonal anti-Dsg3 IgG1 antibodies (pathogenic AK23, AK19 and nonpathogenic AK18, AK20), negative control monoclonal mouse IgG1 and positive control PV-IgG. Cells were treated with IgGs over a time course of 24h, and uPA-protein content and activity in the culture medium were determined by enzyme-linked immunosorbent assay (ELISA) and chromogenic assay, respectively.


RESULTS
The uPA-protein content in samples treated with or without pathogenic, nonpathogenic, control monoclonal mouse IgG1s and PV-IgGs increased continuously up to 24h, with no differences between samples, suggesting a spontaneous secretion. In contrast, uPA activity in the culture medium of cells treated with PV-IgG increased dramatically, whereas that of cells treated with all AK-IgGs and control monoclonal mouse IgG1 did not increase at all.


CONCLUSIONS
These results suggest that PV-IgG-dependent uPA activation is not related to anti-Dsg3 antibody activity, which is an essential factor in PV-IgG acantholysis, and that it may be due to other antigens than Dsg3 or unknown factors contained in PV-IgG fraction.
Yamamoto
Yukari
Y
Department of Dermatology, Gifu University School of Medicine, Yanagido 1-1, Gifu City 501-1194, Japan.
Aoyama
Yumi
Y
Shu
En
E
Tsunoda
Kazuyuki
K
Amagai
Masayuki
M
Kitajima
Yasuo
Y
D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D002478:Cells, Cultured; D003470:Culture Media / Q000378:metabolism; D051184:Desmoglein 3 / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D015603:Keratinocytes / Q000201:enzymology / Q000276:immunology*; D010392:Pemphigus / Q000276:immunology* / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000276:immunology* / Q000378:metabolism
D000911:Antibodies, Monoclonal; D003470:Culture Media; C071894:DSG3 protein, human; D051184:Desmoglein 3; D007074:Immunoglobulin G; D014568:Urokinase-Type Plasminogen Activator