title: Protection against malaria due to innate immunity enhanced by low-protein diet.
abstract: Mice were fed ad libitum with a normal diet (25% protein) or low-protein diets (0-12.5% protein) for a wk and then infected with a nonlethal or lethal strain of Plasmodium yoelii, that is, blood stage infection. The same diet was continued until recovery. Mice fed with a normal diet showed severe parasitemia during nonlethal infection, but survived the infection. They died within 2 wk in the case of lethal infection. However, all mice fed with low-protein diets survived without apparent parasitemia (there were small peaks of parasitemia) in cases of both nonlethal and lethal strains. These surviving mice were found to have acquired potent innate immunity, showing the expansion of NK1.1 -TCRint cells and the production of autoantibodies during malarial infection. Severe combined immunodeficiency (scid) mice, which lack TCRint cells as well as TCRhigh cells, did not survive after malarial infection of lethal strain of P. yoelii, even when low-protein diets were given. These results suggest that low-protein diets enhanced innate immunity and inversely decreased conventional immunity, and that these immunological deviations rendered mice resistant against malaria. The present outcome also reminds us of our experience in the field study of malaria, in which some inhabitants eventually avoided contracting malaria even after apparent malarial infection.
authors.affiliation: Department of Immunology, Niigata University School of Medicine, Japan.
authors.forename: Anoja
authors.initials: A
authors.lastname: Ariyasinghe
authors.forename: Sufi Reza M
authors.initials: SR
authors.lastname: Morshed
authors.forename: M Kaiissar
authors.initials: MK
authors.lastname: Mannoor
authors.forename: Hanaa Y
authors.initials: HY
authors.lastname: Bakir
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kawamura
authors.forename: Chikako
authors.initials: C
authors.lastname: Miyaji
authors.forename: Toru
authors.initials: T
authors.lastname: Nagura
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Kawamura
authors.forename: Hisami
authors.initials: H
authors.lastname: Watanabe
authors.forename: Hiroho
authors.initials: H
authors.lastname: Sekikawa
authors.forename: Toru
authors.initials: T
authors.lastname: Abo
mesh_terms: D000818:Animals; D018753:Diet, Protein-Restricted; D016130:Immunophenotyping; D008099:Liver / Q000166:cytology; D018655:Lymphocyte Count; D008214:Lymphocytes / Q000145:classification / Q000276:immunology; D008288:Malaria / Q000276:immunology* / Q000517:prevention & control*; D051379:Mice; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D018512:Parasitemia / Q000276:immunology / Q000517:prevention & control; D010967:Plasmodium yoelii / Q000276:immunology*; D013154:Spleen / Q000166:cytology; D013950:Thymus Gland / Q000166:cytology