Age-related development and tissue distribution of T cell markers (CD4 and CD8a) in Chinese goose.

Aquatic birds play n critical role in the transmission and dissemination of many important pathogens such as avian influenza virus. The cell-mediated immunity is very important in eliminating the intracellular antigens. Expression of CD4 and CD8 on T cell surface is essential for cell-mediated immune defence and T-cell development. However, the ontogeny of T lymphocytes in waterfowl is scarce and fragmentary. To address these questions, here we report the development and tissues distribution of CD4 and CD8α in goose embryo, gosling and goose by immunocytochemistry assay using monoclonal antibodies. Moreover, the age-related mRNA level of goose CD4 and CD8α in different immune tissues were study by real time quantitative PCR. Our results suggested that the high expression of CD4 and CD8α were readily found in thymus, which peaked at the first week post-hatch. And the highest expression level of CD4 and CD8α were detected in bursa of Fabricius, caecal tonsils, spleen and intestine at the second week, after that the expression level were gradually decreased. Interestingly, the remarkably high expression of CD4 and CD8α in Harderian gland were detected at the first week, which is about hundreds times more than that in other tissues. Our findings demonstrated that the development and the distribution of CD4 and CD8α are partly changed in an age-related way. Moreover, the histological morphogenesis of immune tissues were also discussed. Our results may shed lights on the better understand of T-cell mediate immunity in goose.