In situ characterization of leucocyte subpopulations after infection with Eimeria tenella in chickens

Abstract

We characterized the leucocyte subpopulations after infection with Eimeria tenella in both naive and immune chickens. Immunocytochemical staining was used to characterize the cells in situ, so that the interaction between host and parasite could be studied. More leucocytes were detected in the lamina propria of immune chickens, and leucocytes infiltrated the ceca more rapidly than in naive chickens, but the infiltration was less pronounced than in naive chickens. In naive chickens, most infiltrated leucocytes were macrophages and T cells. Two days after inoculation the number of CD4+ cells had increased greatly. In immune chickens, mainly T cells (CD4+ and CD8+) infiltrated the lamina propria, and in contrast to naive chickens, the number of CD8+ cells exceeded the number of CD4+ cells. Furthermore, we characterized which cells contained a parasite and which cells were detected next to the parasites, because these cells are probably involved in the arrested development of the parasites. In naive chickens, sporozoites were significantly more often located within or next to macrophages than in immune chickens. In immune chickens, sporozoites were significantly more often located within or next to CD3+, CD8+, and TCR2+ cells. In conclusion, the marked increase of CD4+ cells after primary infection suggests that these cells are involved in the induction of the immune response, whereas the increase of CD8+ cells after challenge infection suggests that these cells act as effector cells.

Analysis of Chicken Mucosal Immune Response toEimeria tenellaandEimeria maximaInfection by Quantitative Reverse Transcription-PCR

“…The inflammation observed in Eimeria-infected intestine is associated with an infiltration of macrophages and T cells (38), accompanied by edema and a thickening of the mucosa (27). IL-1␤ is a powerful proinflammatory cytokine secreted by many different cell types, with stimulated macrophages being the main producer.…”

Ups and Downs of Mucosal Cellular Immunity against Protozoan Parasites

“…Eimeria infections induce changes in the intestinal intraepithelial population (7,23). Growth of the parasite in the intestinal epithelium leads to the development of the host immune response and CD8 ϩ cells, which increased in number after challenge infection, seem to act as effector cells in acquired immunity (93).…”

Eimeria tenellaInfection Induces Local Gamma Interferon Production and Intestinal Lymphocyte Subpopulation Changes

“…Several investigations have indicated that cecal tonsil lymphocytes may be involved in the intestinal immune response to Eimeria. For example, during E. tenella infection, an increased number of leukocytes (43) and lymphoid nodules were found in the base of cecal tonsils, accumulating as dense aggregates of lymphocytes containing irregularly scattered lymphoid tissues and germinal centers (8). Cecal tonsil lymphocytes exhibit considerable heterogeneity in surface phenotype and presumably in function (22).…”