title: Apoptotic deletion of Th cells specific for the 19-kDa carboxyl-terminal fragment of merozoite surface protein 1 during malaria infection.
abstract: Immunity induced by the 19-kDa fragment of merozoite surface protein 1 is dependent on CD4+ Th cells. However, we found that adoptively transferred CFSE-labeled Th cells specific for an epitope on Plasmodium yoelii 19-kDa fragment of merozoite surface protein 1 (peptide (p)24), but not OVA-specific T cells, were deleted as a result of P. yoelii infection. As a result of infection, spleen cells recovered from infected p24-specific T cell-transfused mice demonstrated reduced response to specific Ag. A higher percentage of CFSE-labeled p24-specific T cells stained positive with annexin and anti-active caspase-3 in infected compared with uninfected mice, suggesting that apoptosis contributed to deletion of p24-specific T cells during infection. Apoptosis correlated with increased percentages of p24-specific T cells that stained positive for Fas from infected mice, suggesting that P. yoelii-induced apoptosis is, at least in part, mediated by Fas. However, bystander cells of other specificities also showed increased Fas expression during infection, suggesting that Fas expression alone is not sufficient for apoptosis. These data have implications for the development of immunity in the face of endemic parasite exposure.
authors.affiliation: Cooperative Research Center for Vaccine Technology, Queensland Institute of Medical Research, Royal Brisbane Hospital, Queensland, 4029 Australia.
authors.forename: J
authors.initials: J
authors.lastname: Wipasa
authors.forename: H
authors.initials: H
authors.lastname: Xu
authors.forename: A
authors.initials: A
authors.lastname: Stowers
authors.forename: M F
authors.initials: MF
authors.lastname: Good
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis; D017209:Apoptosis; D002460:Cell Line; D002478:Cells, Cultured; D000939:Epitopes / Q000276:immunology; D005260:Female; D005452:Fluoresceins / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D008213:Lymphocyte Activation; D008288:Malaria / Q000276:immunology*; D020066:Merozoite Surface Protein 1 / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010967:Plasmodium yoelii / Q000276:immunology*; D013388:Succinimides / Q000737:chemistry; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000637:transplantation; D019014:fas Receptor / Q000378:metabolism
chemical_list: C087165:5-(6)-carboxyfluorescein diacetate succinimidyl ester; D000913:Antibodies, Protozoan; D000939:Epitopes; D005452:Fluoresceins; D005456:Fluorescent Dyes; D020066:Merozoite Surface Protein 1; D013388:Succinimides; D019014:fas Receptor