title: CTLA-4 blockade differentially influences the outcome of non-lethal and lethal Plasmodium yoelii infections.
abstract: An immune response against malaria has to be tightly controlled. The production of pro-inflammatory cytokines is required to control parasites but the same cytokines are also involved in severe malaria. We have shown that CTLA-4 expression during Plasmodium berghei malaria dampens the immune response. This strain provokes a pro-inflammatory immune response that is associated with the pathology of cerebral malaria. Accordingly a blockade of CTLA-4 during the blood-stage of P. berghei malaria leads to an exacerbation of disease. To analyze the effects of a CTLA-4 blockade in a malaria model which is not prone to immune pathology we employed P. yoelii infection. Blood-stage infection led to a rapid induction of CTLA-4 on T cells. Using the non-lethal P. yoelii strain Py17NL we found that a blockade of CTLA-4 resulted in an increased T cell activation and IFN-gamma production, which was accompanied by a lower peak parasitemia and earlier parasite clearance. In contrast, blockade of CTLA-4 during infection with a P. yoelii strain exhibiting a higher parasitemia induced markedly increased serum-levels of TNF-alpha, which was associated with severe inflammation and reduced survival.
authors.affiliation: Department of Immunology, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Str. 74, 20359 Hamburg, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Lepenies
authors.forename: Iris
authors.initials: I
authors.lastname: Gaworski
authors.forename: Susanne
authors.initials: S
authors.lastname: Tartz
authors.forename: Jean
authors.initials: J
authors.lastname: Langhorne
authors.forename: Bernhard
authors.initials: B
authors.lastname: Fleischer
authors.forename: Thomas
authors.initials: T
authors.lastname: Jacobs
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking / Q000276:immunology / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D015703:Antigens, CD / Q000187:drug effects / Q000276:immunology*; D000943:Antigens, Differentiation / Q000187:drug effects / Q000276:immunology*; D060908:CTLA-4 Antigen; D007249:Inflammation / Q000473:pathology; D007371:Interferon-gamma / Q000097:blood; D008213:Lymphocyte Activation; D008288:Malaria / Q000276:immunology* / Q000473:pathology / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D018512:Parasitemia; D010967:Plasmodium yoelii / Q000472:pathogenicity*; D013601:T-Lymphocytes / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D014774:Virulence
chemical_list: D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma