Evaluation of the Relationship between Alopecia Areata and Viral Antigen Exposure.

Background: Alopecia areata (AA) is an autoimmune disease characterized by non-scarring alopecia with T-cell infiltration at the affected hair follicle.

Objective: Our aim was to study the potential link between hepatitis B virus (HBV) antigen exposure and AA.

Methods: Two pediatric patients with AA following hepatitis B vaccination were identified in a general dermatology clinic. A bioinformatics analysis and an electronic medical record (EMR) database query were performed at the University of Rochester Medical Center to identify patients with AA, coexisting viral infections, vaccinations, or interferon (IFN) therapy in order to determine if the presence of AA and these conditions was higher than in AA patients without these associated conditions or therapy.

Results: An increased frequency of AA among those who received the HBV surface protein antigen [odds ratio (OR) 2.7, p < 0.0001] was identified, and an independent analysis revealed an increased frequency of AA in those receiving IFN-β treatment (OR 8.1, p < 0.05). One potential antigenic target identified was SLC45A2, a melanosomal transport protein important in skin and hair pigmentation. The longest potential vaccine peptide fragment match (8-mer) was to a segment of natural killer (NK) cell inhibitory receptors, KIR3DL2 and KIR3DL1. Predictive modeling of major histocompatibility complex (MHC)-peptide binding demonstrated potential binding of this peptide to MHC relevant to AA.

Limitations: The results will need to be verified in additional patient databases allowing analysis of temporal relationships, and with molecular experiments of the identified antigens.

Conclusions: Our data confirm associations between viral infection and IFN treatment with AA. It establishes that the hepatitis B surface protein antigen has shared epitopes with human killer immunoglobulin-like receptors.