Activation of oral keratinocytes by mercuric chloride: relevance to dental amalgam-induced oral lichenoid reactions.
BACKGROUND
Despite the benefits of mercury-containing amalgam dental fillings there are growing concerns regarding the potential adverse health effects arising from exposure to mercury released from fillings. In some individuals this process may result in a local lichenoid reaction of the oral mucosa.


OBJECTIVE
The aim of this study was to investigate the possibility that mercury salts released from amalgam fillings might act directly on oral keratinocytes to induce changes that could promote the development of such lesions.


METHODS
In vitro experiments were performed in which normal oral and cutaneous keratinocytes were cultured in the presence of mercuric chloride (HgCl2). ICAM-1 expression and the release of cytokines was determined by enzyme-linked immunosorbent assay techniques. T-cell binding to HgCl2-pretreated keratinocytes was assessed using a colorimetric method.


RESULTS
Subcytotoxic concentrations of HgCl2 induced a concentration-related increase in ICAM-1 expression and consequent T-cell binding on oral, but not cutaneous, keratinocytes. HgCl2 also stimulated the release of low levels of tumour necrosis factor-alpha and interleukin-8 (but not RANTES), and inhibited the release of interleukin-1alpha by oral keratinocytes.


CONCLUSIONS
This study provides evidence that oral keratinocytes may play an integral part in initiating the pathogenesis of amalgam-induced lichenoid reactions.
Little
M C
MC
Dermatology Centre, University of Manchester, Hope Hospital, Salford, Manchester M6 8HD, U.K.
Watson
R E
RE
Pemberton
M N
MN
Griffiths
C E
CE
Thornhill
M H
MH
D002448:Cell Adhesion / Q000187:drug effects; D018929:Cell Culture Techniques; D016923:Cell Death / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism; D003723:Dental Amalgam / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D015603:Keratinocytes / Q000187:drug effects* / Q000276:immunology / Q000502:physiology; D017512:Lichenoid Eruptions / Q000139:chemically induced* / Q000276:immunology; D008627:Mercuric Chloride / Q000494:pharmacology*; D009061:Mouth Mucosa / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
D016207:Cytokines; D018799:Intercellular Adhesion Molecule-1; D008627:Mercuric Chloride; D003723:Dental Amalgam