PROFILES OF PULP INFILTRATING LYMPHOCYTES AT VARIOUS TIMES THROUGHOUTFEATHER REGENERATION IN SMYTH LINE CHICKENS WITH VITILIGO

Smyth line (SL) chickens develop a spontaneous, autoimmune, posthatch loss of pigment cells (vitiligo) in regenerating feather tissue. Smyth line vitiligo (SLV) is associated with lymphocyte infiltrations prior to and throughout the development of the disorder, It was the purpose of this study to determine the type, relative amounts, and proportion s of pulp-infiltrating lymphocytes at various times throughout the gro wth of regenerating feathers. Feathers were plucked from 8-week-old ch ickens with and without SLV. Feather pulp cell suspensions were prepar ed when the regenerating feathers were 2, 3, 4, and 6 weeks of age. Ce lls were fluorescently labeled using a panel of mouse monoclonal antib odies specific for chicken lymphocytes. Both T and B cells infiltrated the feather pulp of chickens with SLV. T cell levels remained elevate d throughout the 6 weeks of feather growth, while B cell levels steadi ly declined to control levels over the same time. The pulp-infiltratin g cells were primarily T cells with an alpha beta T cell receptor expr essing the V beta 1 gene (TCR2(+)). The ratio between CD4(+) and CD8() cells was 1.42 and 0.75 in 2- and 6-week-old regenerating feathers f rom chickens with autoimmune SLV, respectively. In non-vitiliginous ch ickens this ratio was always near 1. These data suggest that TCR2(+) T cells play an important role in SLV, CD4(+) cells may play a recruiti ng/activating role, whereas CD8(+) cells may have cytotoxic activity s pecifically directed against melanocytes. Additionally, this is the fi rst report demonstrating the infiltration of B cells into the feather pulp of vitiliginous chickens. These B cells may directly/indirectly c ontribute to melanocyte destruction in SLV.