Characterization of melanocyte-specific autoantibodies in vitiligo-prone Smyth line chickens. (BA2P.128)

Abstract

Abstract Autoimmune vitiligo is characterized by the loss of pigment-producing melanocytes (MC) in the skin. The autoimmune vitiligo-prone Smyth line (SL) of chicken together with the parental Brown line (BL) and vitiligo-resistant Light Brown Leghorn (LBL) chickens constitutes an excellent animal model for this disorder. Although cell-mediated immunity has long been known to contribute to the etiopathology of SL vitiligo (SLV) the role of humoral immunity is less clear. We recently completed a time-course study examining levels of IgG specific to MC lysate in SL and control plasma. Results showed elevated (P<0.05) MC-lysate specific IgG levels in SL chickens 1-2 weeks prior to and throughout SLV development. To evaluate the binding characteristics of MC-specific IgG, primary MC isolated from growing feathers were incubated with IgG purified from the serum of SLV (birds with SLV) and control chickens. IgG binding was evaluated by indirect immunofluorescent staining and flow cytometry. Regardless of the source of MC (SL, BL, LBL), significant binding was only observed with SLV-IgG (mean fluorescence intensity increased approximately 100%). This effect was not observed when MC were incubated with IgG purified from egg yolk of SLV hens. Further characterization of autoantibodies from SLV chickens may provide insight into their role in the loss of MC in SLV. Studies evaluating such mechanisms as antibody-dependent cellular cytotoxicity and complement-mediated cytotoxicity are underway.