Melan-A Positive cells significantly expressed in immune-targeted follicles of Alopecia Areata

Background: Alopecia areata is characterized by patchy hair loss that can extend to affect all body hair and about 2% of population are affected. Many hypotheses for etiopathogenesis exit but autoimmunity after the hair immune privilege collapse is a widely accepted theory. Objectives: The aim of this study is to examine the expression of Melan A within hair follicles of alopecia areata as one of the melanocytic markers, in order to correlate melanocyte existence to the induction of the disease. Methods: Cross sectioned hair follicles within alopecia areata specimens were examined by routine H&E and immunehistochemically for the Melan A marker in 16 alopecia areata patients. Results: Within the 82 examined alopecia areata follicles, 50 showed positive cellular expression of Melan A. Positive cells ranged from 1 to 20 per follicle. There was a significant increase in count of Melan A positive cell in immune-targeted follicles of alopecia areata with significant positive correlation. Conclusions: Melan A is clearly expressed in hair follicles of alopecia areata within bulbar region and the suprabulbar outer root sheath and the expression is significantly correlated to the immune mononuclear infiltrates that accompany the pathogenesis of the disease. This relevant finding may confirm that melanocytes carry the antigenic epitope required to initiate the organ specific autoimmunity in alopecia areata and also explain the regrowth of only white hair follicles in some cases with alopecia and the mysterious Thomas More syndrome.