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- Nylen, S, et al.
(författare)
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Differential induction of cellular responses by live and dead Leishmania promastigotes in healthy donors
- 2001
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Ingår i: Clinical and experimental immunology. - : Oxford University Press (OUP). - 0009-9104 .- 1365-2249. ; 124:1, s. 43-53
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Tidskriftsartikel (refereegranskat)abstract
- The most effective protection against human leishmaniasis has been achieved following vaccination with live promastigotes. Killed promastigotes + BCG can protect, albeit to a lower degree. To explore what mechanisms may be involved in these differences, the ability of live and dead promastigotes to induce immune responses were evaluated in vitro. The data showed that live and dead promastigotes differ in their ability to induce proliferation and cytokine production. Cytokine gene expression of Th1 related cytokines (IL-12, IFNγ and TNFα) in adult PBMC was more evident to live than to heat killed promastigotes. This was coupled with significantly higher number of IFNγ secreting cells induced by live than killed promastigotes. However, α-IL-12 antibodies did not block the IFNγ response induced by live promastigotes. Proliferative responses were variable. In contrast to adult PBMC no IFNγ secreting MNC could be detected in cord blood. However, in these cells the live promastigotes consistently induced higher proliferative response compared to dead. Implications of these findings are discussed.
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- Nylen, S, et al.
(författare)
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Live Leishmania promastigotes can directly activate primary human natural killer cells to produce interferon-gamma
- 2003
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Ingår i: Clinical and experimental immunology. - : Oxford University Press (OUP). - 0009-9104 .- 1365-2249. ; 131:3, s. 457-467
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Tidskriftsartikel (refereegranskat)abstract
- Natural killer (NK) cells have been implicated in the natural protection and healing of leishmaniasis by their ability to secrete the macrophage activating cytokine interferon (IFN)γ. Previous studies have demonstrated that early production of interleukin (IL)-12 triggers IFNγ secretion by NK cells. Here we report that live Leishmania promastigotes (the form that is injected by the vector) can directly induce human peripheral blood NK cells from healthy donors to IFNγ secretion in the absence of IL-12 and professional antigen presenting cells. Killing of promastigotes abolishes this property. This novel mechanism of activation of the innate immune response may be relevant for establishment of infection and thus also the design of vaccines against leishmaniasis.
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