Investigation of the inflammatory mechanisms in alopecia areata.

We aimed to investigate the profile of the inflammatory infiltrate in lesional and nonlesional tissue in alopecia areata (AA) and look for possible associations between inflammatory mechanisms, neuropeptide expressions, and various clinical features. Twenty-four patch-type AA patients were included. Forty-eight lesional and nonlesional skin samples were stained immunohistochemically with antibodies for CD1a, CD3, CD4, CD8, CD20, CD57 (for natural killer cells), mast cell tryptase, nerve growth factor receptor (NGFR), and substance P (SP). Various clinical findings were recorded. Psychological distress levels and stress-related hormones were measured. Lesional skin showed statistically more CD3(+), CD8(+), and CD57(+) lymphocytes, mast cells, Langerhans cells, and more prominent immunoreactivities of NGFR and SP (P < 0.003). Most nonlesional skin showed CD3(+) and CD57(+) cells, mast cells, and NGFR(+) nerve fibers. NGFR and SP, and SP and perivascular mast cell infiltrates were correlated, whereas peribulbar mast cells and anagen follicle counts were inversely correlated in nonlesional skin (P < 0.05). Near half of the patients' distress levels were high. No relationship among biochemical, psychological, and clinical parameters could be shown. AA may involve the entire skin in which lesions occur as a result of local T cell-mediated cytotoxic inflammatory response initiated by Langerhans cells and mast cells activated via neuropeptides.