Plasmodium falciparum sexual stage antigens: immunogenicity and cell-mediated responses.
Antibody and cell-mediated immune responses to the transmission-blocking target antigens of Plasmodium falciparum, Pfs 48/45, were determined in infected non-immune patients and in immune individuals from an endemic area. Characterization of the B cell epitopes with monoclonal antibodies showed that there were five regions identifiable but there could be interactions between them causing either competitive or enhancing effects. Sera from infected non-immune patients contained antibodies that would compete with one or more of the mAbs to the different epitopes. Immune responsiveness to purified Pfs 48/45 in P. falciparum-immune adults measured as lymphoproliferation, production of interferon-gamma, or as Pfs 48/45-specific antibody was very limited. This did not appear to be due to MHC class II restriction, to diversity in structure of the parasite antigens or to a failure of immunological memory. The antibody-response data were more consistent with down-regulation of immunity as a result of prolonged exposure to infection.
Targett
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GA
Department of Medical Parasitology, London School of Hygiene and Tropical Medicine, U.K.
Harte
P G
PG
Eida
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S
Rogers
N C
NC
Ong
C S
CS
D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal; D000913:Antibodies, Protozoan / Q000032:analysis; D000953:Antigens, Protozoan / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D002648:Child; D015536:Down-Regulation; D000939:Epitopes / Q000276:immunology; D005854:Germ Cells / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D007156:Immunologic Memory; D008285:Major Histocompatibility Complex / Q000276:immunology; D008288:Malaria / Q000276:immunology; D010963:Plasmodium falciparum / Q000276:immunology*; D015800:Protozoan Proteins / Q000276:immunology*; D012008:Recurrence
D000911:Antibodies, Monoclonal; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D000939:Epitopes; D015800:Protozoan Proteins; C064783:sexual stage specific protein, Plasmodium