T lymphocytes and altered keratinocytes express interferon-gamma and interleukin 6 in lichen planus.
Lichen planus is assumed to represent a delayed hypersensitivity reaction, in the course of which cytokines control the proliferation and differentiation of cytotoxic T lymphocytes which attack the epidermis and cause apoptosis of undifferentiated keratinocytes. Since interferon-gamma and interleukin 6 are known to be markedly generated in lichen planus, we investigated the cellular localization of these cytokines in affected skin/oral mucosa biopsy specimens using in situ hybridization for interferon-gamma and in situ reverse transcription-polymerase chain reaction for interleukin 6 mRNA. In the upper subepithelial connective tissue interferon-gamma mRNA was noted within proliferating CD3+ T lymphocytes. In this tissue compartment interleukin 6 mRNA was detected in infiltrating CD4+ and CD8+ T lymphocytes. In the epithelium, expression of interferon-gamma mRNA and interleukin 6 mRNA was observed in the basal and suprabasal keratinocytes of altered skin/oral mucosa. In contrast, normal skin did not reveal any interferon-gamma or interleukin 6 expression, although a few CD4+ and CD8+ T lymphocytes were noted in the dermis as well as the epidermis. These findings indicate that in lichen planus the proinflammatory cytokines interferon-gamma and interleukin 6 are produced not only by activated T lymphocytes but also by altered keratinocytes, and suggest that stimulated keratinocytes may amplify the course of lichen planus.
Fayyazi
A
A
Department of Pathology, Georg-August University, Göttingen, Germany.
Schweyer
S
S
Soruri
A
A
Duong
L Q
LQ
Radzun
H J
HJ
Peters
J
J
Parwaresch
R
R
Berger
H
H
D001706:Biopsy; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007371:Interferon-gamma / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D015603:Keratinocytes / Q000378:metabolism*; D008010:Lichen Planus / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012867:Skin / Q000378:metabolism / Q000473:pathology; D013601:T-Lymphocytes / Q000378:metabolism*
D015850:Interleukin-6; D012333:RNA, Messenger; D007371:Interferon-gamma