Ex vivo killing of primary melanocytes by syngeneic mononuclear cells from active, autoimmune vitiligo lesions in Smyth chickens (BA7P.152)

Abstract

Abstract In humans autoimmune vitiligo is characterized by the loss of pigment-producing melanocytes in the skin. The vitiligo-prone Smyth line (SL) chicken together with the MHC-matched parental Brown line (BL) and vitiligo-resistant Light Brown Leghorn line of chickens constitute a spontaneous, non-transgenic animal model for this disorder. Cell-mediated immunity (CMI) is known to contribute to the etiopathology of vitiligo. Furthermore, CMI was demonstrated in vivo in vitiliginous SL chickens based on the delayed wattle response (DWR) to melanocyte lysates. Immunohistochemical analysis of DWR-positive tissue revealed extensive T cell infiltration indicative of a CMI response. In order to examine CMI in SL vitiligo (SLV) ex vivo we developed a co-culture assay using primary effector and target cells from growing feathers (the target tissue). Mononuclear cells (MNCs) were harvested from feathers of chickens with active SLV and BL controls. Target cells (melanocytes) were isolated from pigmented feathers prior to development of SLV. To detect melanocyte-specific death a modified flow cytometric method of Lee-MacAry et al (2001) was used. Regardless of whether melanocytes were isolated from chickens that did or did not eventually develop SLV, co-culture with MNCs from SLV chickens resulted in greater melanocyte death compared to controls. Use of this ex vivo system with sorted MNCs from active, autoimmune SLV lesions will help identify roles of individual subsets in melanocyte death.