T cell phenotype and intracellular IFN- γproduction in peritoneal exudate cells and gut intraepithelial lymphocytes during acute Toxoplasma gondii infection in mice

Abstract

Although there are many reports on the splenic (systemic) T cell response afterToxoplasma gondii infection, little information is available regarding the local T cellresponses of peritoneal exudate cells (PEC) and gut intraepithelial lymphocytes (IEL)following peroral infection with bradyzoites. Mice were infected with 40 cysts of the 76Kstrain of T. gondii, and then sacrificed at days 0, 1, 4, 7 and 10 postinfection (PI). Thecellular composition and T cell responses of PEC and IEL were analyzed. The total numberof PEC and IEL per mouse increased after infection, but the ratio of increase was higher inIEL. Lymphocytes were the major component of both PEC and IEL. The relative percentagesof PEC macrophages and neutrophils/eosinophils increased significantly at day 1 and 4 PI,whereas those of IEL did not change significantly. The percentage of PEC NK1.1 and γδTcells peaked at day 4 PI (p < 0.0001), and CD4 and CD8 α T cells increased continuouslyafter infection. The percentages of IEL CD8 αand γδT cells decreased slightly at first, andthen increased. CD4 and NK1.1 T cells of IEL did not change significantly after infection.IFN-γ-producing PEC NK1.1 T cells increased significantly from day 1 PI, but the other Tcell subsets produced IFN- γabundantly thereafter. The proportion of IEL IFN- γ-producingCD8 αand γδT cells increased significantly after infection, while IEL NK1.1 T cells hadsimilar IFN-γproduction patterns. Taken together, CD4 T cells were the major phenotypeand the important IFN- γ-producing T cell subsets in PEC after oral infection with T. gondii,whereas CD8 α T cells had these roles in IEL. These results suggest that PEC and IELcomprise different cell differentials and T cell responses, and according to infection routethese factors may contribute to the different cellular immune responses.