Séguin R, Kasper L H
Department of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA.
J Infect Dis. 1999 Feb;179(2):467-74. doi: 10.1086/314601.
Dendritic cells (DC) are potent antigen-presenting cells that can stimulate T cell responses by secreting cytokines. During Toxoplasma gondii infection, host immunity is mediated by interferon-gamma, which is induced by interleukin-12 (IL-12). Whether T. gondii infection would stimulate human DC to produce IL-12 was determined. DC were generated from human peripheral blood mononuclear cells cultured with recombinant human granulocyte-macrophage colony-stimulating factor and recombinant human IL-4. DC secreted high levels of IL-12 in response to lipopolysaccharide but not to either live T. gondii tachyzoites or soluble antigen. However, IL-12 production in response to T. gondii was observed when DC were cocultured in contact with lymphocytes isolated from seropositive donors. Ligation of CD40:CD154 was partially essential for IL-12 secretion. These data demonstrate that signals obtained from contact with sensitized lymphocytes are critical for human DC to secrete IL-12 in response to T. gondii.
树突状细胞（DC）是强大的抗原呈递细胞，可通过分泌细胞因子刺激T细胞反应。在弓形虫感染期间，宿主免疫由干扰素-γ介导，而干扰素-γ由白细胞介素-12（IL-12）诱导产生。本研究确定了弓形虫感染是否会刺激人DC产生IL-12。DC由用人重组粒细胞-巨噬细胞集落刺激因子和人重组IL-4培养的人外周血单核细胞生成。DC对脂多糖有反应时会分泌高水平的IL-12，但对活的弓形虫速殖子或可溶性抗原均无反应。然而，当DC与从血清反应阳性供体分离的淋巴细胞共培养时，可观察到DC对弓形虫产生IL-12。CD40:CD154的连接对于IL-12分泌部分必需。这些数据表明，与致敏淋巴细胞接触获得的信号对于人DC响应弓形虫分泌IL-12至关重要。
