Serum granulysin as a possible key marker of the activity of alopecia areata

BackgroundAlopecia areata (AA) is an organ-restricted autoimmune condition of the hair follicles (HFs) that presents as nonscarring hair loss. A collapse of immunoprivilege for cell-mediated cytotoxicity and following attacks by cytotoxic T cells to anagen HFs are considered to play a major role in the pathogenesis of AA. However, there has been no useful marker for the activity of AA to date.ObjectiveThe aim of this study is to examine whether granulysin, which is known to reflect the activity of cytotoxic immune responses, is related to the disease activity of AA.MethodsWe evaluated serum granulysin levels in acute and chronic AA patients compared to healthy controls in the perspective of bald skin areas, prognosis, and co-existence of other allergic diseases. In addition, immunohistochemical analysis for granulysin-, CD4-, CD8-, and CD56-positive cells in the lesional skin of acute and chronic AA patients was performed.ResultsSerum granulysin levels were significantly elevated in both acute and chronic AA patients (p = 0.00081 and p = 0.0012, respectively). Intriguingly, serum granulysin levels were significantly associated with the broader bald skin areas (Spearman's r = 0.59, p = 0.017), and poorer prognosis in acute AA patients (p = 0.0080). They were also associated with co-existence of allergic disorders in AA patients (p = 0.026). Immunohistochemical staining demonstrated that perifollicular granulysin-bearing cells were mainly detected in acute AA lesions with dense lymphocytic infiltration, and that these granulysin-bearing cells were consistent with CD8+ T cells.ConclusionThe serum granulysin level may be a useful and novel marker for the disease activity in the acute phase of AA.