HLA and ICAM-1 expression in alopecia areatain vivoandin vitro: the role of cytokines

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Abstract
To investigate the hypothesis that aberrant HLA and adhesion molecule expression in alopecia areata (AA) are secondary to local release of interferon-gamma (IFN-γ) or other cytokines. we have studied HLA ABC. -DQ. -DR and ICAM-1 expression by immunohistochemistry, and compared patterns of expression in lesional tissue sections with those observed in hair follicles maintained in short-term organ culture, both from normal individuals and non-lesional sites in AA patients. The organ cultures were supplemented with IFN-γ, tumour necrosis factor-alpha (TNE-α), and granulocyte-macrophage colony stimulating factor (GM-CSE). in a range of doses. In lesional AA tissue sections, there was close spatial correlation of ICAM-1 with HLA-DR; prominent staining being noted in the pre-cortical matrix and dermal papilla (DP) of lesional anagen follicles. In cultured follicles, dose-dependent induction of HLA class I. DR and ICAM-1 by IFN-γ, and HLA class I and ICAM-1, but not HLA-DR. by TNE-α was observed in follicular epithelium, mainly in the outer root sheath (ORS). The findings in these cultures were the same in follicles derived from normal individuals and AA patients. Cytokine-induced patterns of HLA and ICAM-1 expression observed in vitro in cultured follicles differed significantly from those observed in vivo in lesional tissue sections. In particular, IFN-γ failed to induce HLA-DR expression in the pre-cortical matrix and dermal papilla (DP), sites where this is usually observed in AA. The results suggest local cytokine release is not the sole determinant of aberrant HLA-DR expression in AA.

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