Immunohistochemical evaluation of vitiliginous hair follicle melanocyte reservoir: is it retained?

Abstract

Vitiligo is an acquired depigmentaion of skin and hair. The presence of white hair within vitiligo lesions is considered a bad prognostic sign since these lesions are difficult to repigment. Melanocyte reservoir was not extensively studied in vitiliginous white hair. To evaluate pigment cell reservoir in vitiliginous black and white hair. Using immunohistochemical technique, skin biopsies from 30 vitiligo patients (including either black or white hair) and 10 age- and gender-matched healthy subjects were examined. Human Melanoma Black-45 (HMB-45) was used for detecting active melanocytes and Tyrosinase Related Protein 2 (TRP2) for detecting the whole melanocyte lineage including melanocyte stem cells (MelSC). About 61.1% of black hair was positive for HMB-45 and 83.3% was positive for TRP2. About 25% of white hair was positive for HMB-45 and 75% retained TRP2 positivity. Follicular HMB-45 expression and TRP2 expression percentage were significantly lower in white than black hair (P=0.05, 0.04 respectively). Epidermal HMB-45 and TRP2 expression percentages were significantly higher in lesions containing black rather than white hair (P<0.001, P=0.05 respectively). Black hair was significantly associated with histologically pigmented hair follicles (P=0.049), and with residual interfollicular melanin pigment (P=0.007). Melanocytes, either active (melanotic) or inactive (amelanotic which may include MelSC), are not totally absent from vitiliginous white hair. However, intact melanocyte reservoir was observed more in black than white hair. This may add avenues for future research about the possibility of white vitiliginous hair to repigment.