HLA AND ICAM-1 EXPRESSION IN ALOPECIA-AREATA IN-VIVO AND IN-VITRO - THE ROLE OF CYTOKINES

To investigate the hypothesis that aberrant HLA and adhesion molecule expression in alopecia areata (AA) are secondary to local release of i nterferon-gamma (IFN-gamma) or other cytokines, we have studied HLA AB C, -DQ, -DR and ICAM-1 expression by immunohistochemistry, and compare d patterns of expression in lesional tissue sections with those observ ed in hair follicles maintained in short-term organ culture, both from normal individuals and non-lesional sites in AA patients. The organ c ultures were supplemented with IFN-gamma, tumour necrosis factor-alpha (TNF-alpha), and granulocyte-macrophage colony stimulating factor (GM -CSF), in a range of doses. In lesional AA tissue sections, there was close spatial correlation of ICAM-1 with HLA-DR; prominent staining be ing noted in the pre-cortical matrix and dermal papilla (DP) of lesion al anagen follicles. In cultured follicles, dose-dependent induction o f HLA class I, DR and ICAM-1 by IFN-gamma, and HLA class I and ICAM-1, but not HLA-DR, by TNF-alpha was observed in follicular epithelium, m ainly in the outer root sheath (ORS). The findings in these cultures w ere the same in follicles derived from normal individuals and AA patie nts. Cytokine-induced patterns of HLA and ICAM-1 expression observed i n vitro in cultured follicles differed significantly from those observ ed in vivo in lesional tissue sections. In particular, IFN-gamma faile d to induce HLA-DR expression in the pre-cortical matrix and dermal pa pilla (DP), sites where this is usually observed in AA. The results su ggest local cytokine release is not the sole determinant of aberrant H LA-DR expression in AA.