Increased lymphocyte subpopulations and macrophages in the ovaries and oviducts of laying hens infected with Salmonella enterica serovar Enteritidis

Salmonella enterica serovar Enteritidis ( SE) is a causative agent for human food poisoning cases throughout the world. The ovaries and the oviducts of the laying hens are the major sites of SE colonization from which vertical transmission to eggs occurs. In this study, Salmonella-induced changes in T lymphocytes, B lymphocytes and macrophages in the ovaries and oviducts were assessed after primary and secondary experimental inoculations of laying hen with SE. Statistically significant increases in the numbers of T cells (both CD4(+) and CD8(+)) and macrophages were observed 7 to 14 days after primary inoculation, followed by a peak in B-cell numbers from the 14th day post-primary inoculation onwards in the secretory areas of the oviducts. The peak in lymphocyte numbers immediately preceded a decline in the rate of SE recovery from the reproductive tract beginning at day 14. The correlation of decreased Salmonella recovery with elevated lymphocyte and macrophage numbers strongly suggests that local cell-mediated immunity is involved in controlling SE injection in the ovaries and oviducts.