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1 February 2008 Transcriptional Inhibition of Interleukin-12 Promoter Activity in Leishmania Spp.–Infected Macrophages
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To establish and persist within a host, Leishmania spp. parasites delay the onset of cell-mediated immunity by suppressing interleukin-12 (IL-12) production from host macrophages. Although it is established that Leishmania spp.-infected macrophages have impaired IL-12 production, the mechanisms that account for this suppression remain to be completely elucidated. Using a luciferase reporter assay assessing IL-12 transcription, we report here that Leishmania major, Leishmania donovani, and Leishmania chagasi inhibit IL-12 transcription in response to interferon-gamma, lipopolysaccharide, and CD40 ligand and that Leishmania spp. lipophosphoglycan, phosphoglycans, and major surface protein are not necessary for inhibition. In addition, all the Leishmania spp. strains and life-cycle stages tested inhibited IL-12 promoter activity. Our data further reveal that autocrine-acting host factors play no role in the inhibitory response and that phagocytosis signaling is necessary for inhibition of IL-12.

Asha Jayakumar, Robyn Widenmaier, Xiaojing Ma, and Mary Ann McDowell "Transcriptional Inhibition of Interleukin-12 Promoter Activity in Leishmania Spp.–Infected Macrophages," Journal of Parasitology 94(1), 84-93, (1 February 2008).
Received: 6 December 2006; Accepted: 1 June 2007; Published: 1 February 2008

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