Effect of selection for delayed amelanosis on immune response in chickens. 1. Antibody production

Effect of genetic selection for group productivity and longevity on immunological and hematological parameters of chickens

A line of White Leghorn chickens was selected for high group productivity and longevity resulting in improved survival and feather score as well as reduced cannibalism and flightiness. Improvements in survival might have also been due to improved immunity. The present study was designed to test the hypothesis that selection for high (HGPS) and low (LGPS) group productivity and survivability also altered immune and hematological parameters. The LGPS line was an intense reverse selected line of the HGPS line at the eighth generation of development. Hens were randomly assigned to individual cages at 17 wk of age. Blood samples were collected from the hens at 21 wk of age. Subsets of T lymphocytes (CD4+, CD8+, and gammadelta cells) were measured using flow cytometry. Concentrations of plasma IgG were quantified with western blot analysis and immunoprecipitation assay. Hematological parameters were collected from blood smears. The HGPS hens had significantly higher percentages of blood lymphocytes and CD4+:CD8+ ratios of circulating T cells (P < 0.01) and tended to have more, but not significantly, gammadelta T cells (P = 0.07) than the LGPS hens. In contrast, the LGPS hens exhibited eosinophilia and heterophilia and greater heterophil:lymphocyte ratios (P < 0.01). The concentrations of plasma IgG were also significantly higher in the LGPS hens (P < 0.01). These results suggest that genetic selection for group productivity and longevity also alters the immunological and hematological systems of hens. The line difference in regulation of T cells, leukocytes, and production of IgG may suggest that different genes or modes of gene action are involved.

The detection of melanocyte autoantibodies in the Smyth chicken model for vitiligo

Smyth line (SL) chickens are phenotypically characterized by a posthatch depigmentation (vitiligo) of the feathers. The destruction of melanocytes in the feather follicle as well as in other tissues such as the choroid is genetically determined. Previous studies have shown that bursectomy or treatment with immunosuppressive agents decreases the incidence and severity of SL depigmentation (1). These observations implicate a role for the immune system, specifically the humoral component, in melanocyte destruction. In this study we show that there are circulating melanocyte-specific autoantibodies in the sera of depigmented SL chicks which are not present in sera from Light Brown Leghorn (LBL) control chicks. By immunoblots and by immunoprecipitation of radiolabeled melanocyte proteins, SL autoantibodies were shown to bind to multiple melanocyte proteins between 65 and 80 kDa. These proteins are not detected in SL fibroblasts. By immunoblotting, the incidence of autoantibodies for these 65- to 80-kDa proteins was determined to be 95% in depigmented SL chicks (n = 20), 0% in normally pigmented SL chicks (n = 8), and 5% in LBL chicks (n = 20). Melanocyte autoantibodies are detectable in the sera of affected chicks at or several weeks prior to the expression of depigmentation. This information, plus previously published data, implicate melanocyte autoantibodies in the depigmentary phenomenon of vitiligo observed in Smyth line chickens.