Browsing by Author "Kamau, Timothy"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Cytokine Production in Whole Blood Cultures from a Fishing Community in an Area of High Endemicity for Schistosoma mansoni in Uganda: the Differential Effect of Parasite Worm and Egg Antigens
    (American Society for Microbiology, 2003-03) Jones, Frances M; Kimani, Gachuhi; Mwatha, Joseph K; Kamau, Timothy; Kazibwe, Francis; Kemijumbi, Jovanice; Kabatereine, Narcis B; Booth, Mark; Kariuki, Henry C.; Ouma, John H.; Vennervald, Birgitte J; Dunne, David W.; Oseph, Sarah J
    The human host is continuously exposed to the egg and the adult worm developmental stages of Schistosoma mansoni during chronic infections with the parasite. To assess the cytokine responses induced by these different costimulating stages and how they are influenced by host age and infection intensity, whole blood samples from a cross-sectional cohort of 226 members of a Ugandan fishing community who had been resident in an area with high transmission of S. mansoni for the previous 10 years or from birth were stimulated with S. mansoni egg antigen (SEA) or worm antigen (SWA). SWA-specific gamma interferon (IFN-_) production increased with age, and the levels of SWA- and SEA-specific interleukin 3 (IL-3) were weakly correlated with schistosome infection intensity. The production of most cytokines was little affected by age or infection intensity but was either SEA or SWA specific. One hundred thirty-two members of the cohort coproduced IL-5 and IL-13 specifically in response to SWA, whereas only 15 produced these cytokines, and at much lower levels, in response to SEA. IL-10, IL-4, and IFN-_ were also produced in response to SWA, whereas the response to SEA consisted almost exclusively of IL-10. Our results suggest that, in contrast to what has been described for the murine model of S. mansoni and during acute human infections, chronic intense exposure to and infection with S. mansoni in this cohort resulted in very low levels of response to SEA in vitro in the presence of a vigorousand mixed Th1-Th2 response to SWA.
  • Thumbnail Image
    Item
    Increases in Human T Helper 2 Cytokine Responses to Schistosoma mansoni Worm and Worm- Tegument Antigens Are Induced by Treatmentwith Praziquantel
    (Infectious Diseases Society of America, 2004-07-24) Joseph, Sarah; M., Frances; Klaudia Walter, Jones; Fulford, Anthony J.; Kimani, Gachuhi; Mwatha, Joseph. K; Kamau, Timothy; Kariuki, Henry C; Kazibwe, Francis; Tukahebwa, Edridah; Kabatereine, Narcis B.; Ouma, John H.; Vennervald, Birgitte J.; Dunne, David W.
    Levels of Schistosoma mansoni–induced interleukin (IL)–4 and IL-5 and posttreatment levels of immunoglobulin E recognizing the parasite’s tegument (Teg) correlate with human resistance to subsequent reinfection after treatment. We measured changes in whole-blood cytokine production in response to soluble egg antigen (SEA), soluble worm antigen (SWA), or Teg after treatment with praziquantel (PZQ) in a cohort of 187 individuals living near Lake Albert, Uganda. Levels of SWA-induced IL-4, IL-5, IL-10, and IL-13 increased after treatment with PZQ, and the greatest relative increases were seen in the responses to Teg. Mean levels of Teg-specific IL- 5 and IL-10 increased ∼10–15-fold, and mean levels of IL-13 increased ∼5-fold. Correlations between the changes in cytokines suggested that their production was positively coregulated by tegumentally derived antigens. Levels of SEA-, SWA-, and Teg-induced interferon-g were not significantly changed by treatment, and, with the exception of IL-10, which increased slightly, responses to SEA also remained largely unchanged. The changes in cytokines were not strongly influenced by age or intensity of infection and were not accompanied by corresponding increases in the numbers of circulating eosinophils or lymphocytes