Analysis of splenic and thymic lymphocyte subpopulations in chickens infected with Salmonella enteritidis.

Lymphocytes expressing CD3, CD4, CD8, pan lymphocyte, IgA, IgG and IgM cell surface antigens were assessed by in the spleen and thymus of chickens following infection with Salmonella enteritidis using flow cytometric analysis. At 6 days post primary infection and 2 days post secondary infection with S. enteritidis, the percentages of IgA+ and IgM+ lymphocytes in the spleen were significantly increased (P < 0.05). At 2 days post secondary infection with S. enteritidis, the percentage of CD4+ T lymphocyte in the spleen and CD8+ T lymphocyte percentage in the thymus were significantly increased (P < 0.05). These results indicate that S. enteritidis infection induces changes in the spleen and thymus that reflect the dynamics of the host protective immune response.