Autocytotoxic T-cell clones in lichen planus

Area of Science:

• Immunology
• Dermatology
• Cell Biology

Background:

• Lichen planus (LP) is an inflammatory condition affecting skin and mucous membranes.
• The precise mechanisms of keratinocyte damage in LP are not fully understood.
• T cells play a crucial role in immune responses, including cytotoxic functions.

Purpose of the Study:

• To investigate the in vitro cytotoxic activity of T cells from LP patients against autologous keratinocytes.
• To identify the T cell subsets responsible for keratinocyte lysis in LP lesions.
• To elucidate the mechanism by which T cells induce keratinocyte death in LP.

Main Methods:

• Culture and cloning of T cells and keratinocytes from LP lesions and normal skin.
• Immortalization of keratinocytes using human papillomavirus 16 (HPV16) E6/E7 genes.
• Assessment of T cell cytotoxic activity against keratinocytes and B cells.
• Blocking experiments using anti-MHC class I antibodies.

Main Results:

• Lesional T cell lines and clones exhibited significantly higher cytotoxicity against autologous lesional keratinocytes compared to non-lesional T cells.
• Most cytotoxic LP T cell clones were CD8+, while non-cytotoxic clones were CD4+.
• CD8+ LP T cell clones demonstrated dose-dependent killing of keratinocytes, but not B cells.
• Cytotoxicity was partially inhibited by anti-MHC class I antibodies, suggesting antigen recognition.

Conclusions:

• CD8+ T cells in LP lesions are cytotoxic towards autologous keratinocytes.
• These CD8+ cytotoxic T cells likely recognize antigens presented by MHC class I molecules on keratinocytes.
• The findings support a model where CD8+ cytotoxic T cells contribute to keratinocyte lysis in LP lesions.