Flow cytometric analysis of T lymphocyte subpopulations in large-bodied turkey lines and a randombred control population

To investigate the effect of BW selection on immune cell populations of turkeys, T lymphocyte subpopulation analyses were conducted using peripheral blood from lines selected for increased BW and a randombred control population. The lines used included an experimental line (F) selected long-term for increased 16 wk BW, a randombred control line (RBC2) that served as the base population of the F line, and sire lines (A and B) from each of two major commercial turkey breeders. The peripheral blood lymphocytes were isolated and stained with mouse anti-chicken CD4 and CD8alpha antibodies in flow cytometric analysis. The polymorphism of CD8alpha in the F and A lines detected with the CT8 monoclonal antibody (mouse anti-chicken CD8alpha antibody) did not appear to be associated with BW and shank parameters. The present results showed that the F line had a significantly larger CD4+CD8- T cell subpopulation than did the RBC2 line at both ages, and this population proportion in the F line was also larger than that for one commercial sire line at 24 wk of age. There were no differences in other T cell subsets. The BW selection may have resulted in changes in T lymphocyte subpopulations and, therefore, may have affected disease resistance. The increased susceptibility to infectious diseases in the F line may be associated with the higher CD4+CD8- T cell subpopulation and the CD8alpha polymorphism.