Involvement of granzyme B and granulysin in the cytotoxic response in lichen planus.
BACKGROUND
Lichen planus is an inflammatory dermatosis involving either skin and/or mucosal epithelial surfaces. A cell-mediated cytotoxicity response is the main suspected mechanism of this dermatosis. Granzyme B and granulysin are components of the cytoplasmic granules of cytotoxic T lymphocytes and natural killers. They are involved in cell-mediated apoptosis. This work studies the possible implication of granzyme B and granulysin in the cell-mediated cytotoxicity response in lichen planus.


METHODS
In situ expression of granzyme B and granulysin was studied by real-time reverse transcriptase polymerase chain reaction in 15 biopsies of lichen planus. The distribution and the phenotype of the inflammatory infiltrate and the expression of granzyme B were studied by immunohistochemistry in seven other biopsies of lichen planus.


RESULTS
Granzyme B and granulysin mRNA expression was one to two hundred times greater than in biopsies of normal skin. Immunohistochemical study revealed that the lymphohistiocytic infiltrate consisted mainly of CD4+ and CD8+ lymphocytes. Granzyme B+ cells were observed close to apoptotic keratinocytes.


CONCLUSIONS
Our results suggest a central role for cell-mediated cytotoxicity by the granule exocytosis pathway probably because of auto-cytotoxic T-cell clones in the pathogenesis of lichen planus.
Ammar
M
M
Laboratoire d'Immunologie, de Génétique et de Pathologie Humaine, Faculté des Sciences, Tunis, Tunisie. myriambensaid@yahoo.fr
Mokni
M
M
Boubaker
S
S
El Gaied
Amel
A
Ben Osman
A
A
Louzir
H
H
D000293:Adolescent; D000328:Adult; D015703:Antigens, CD / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics / Q000378:metabolism*; D017209:Apoptosis / Q000276:immunology; D002648:Child; D005260:Female; D053804:Granzymes / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D008010:Lichen Planus / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012867:Skin / Q000473:pathology; D018709:Statistics, Nonparametric; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C075005:GNLY protein, human; D012333:RNA, Messenger; D053804:Granzymes