Taubert Anja, Hermosilla Carlos, Sühwold Anke, Zahner Horst
Institute of Parasitology, Justus Liebig University Giessen, Rudolf-Buchheim-Str. 2, D-35392 Giessen, Germany.
Vet Immunol Immunopathol. 2008 Dec 15;126(3-4):309-20. doi: 10.1016/j.vetimm.2008.09.003. Epub 2008 Sep 19.
Cellular immune responses against Eimeria bovis are highly specific and a key factor for the development of protection against challenge infections. In this study we investigate the cellular immune responses of E. bovis primary and challenge infected calves stimulated in vitro by E. bovis merozoite I-antigen. Primary infection was accompanied by an increase of IFN-gamma and IL-2 gene transcription in whole blood samples, peaking during prepatency (8-12 days p.i.) and declining thereafter, whereas IL-4 gene transcription was induced predominantly in patency. IL-10 mRNA was not influenced by E. bovis infection. Both CD4+ and CD8+ T cells were identified as source of IFN-gamma gene transcripts, whilst IL-2 and IL-4 gene transcription was enhanced mainly in CD4+ T cells. Increased levels of IFN-gamma transcripts and protein were also found in lymphocytes isolated from ileocaecal lymph node biopsy 8 days p.i., and in cell culture supernatants obtained from antigen-stimulated peripheral blood mononuclear cells (PBMC) at days 8 and 12 p.i., respectively. Challenge infections of calves influenced neither IFN-gamma nor IL-2 gene transcription in peripheral blood or in lymph node-derived lymphocytes. In contrast, IL-4 gene transcription was increased in lymphocytes isolated from draining lymph nodes. Besides antigen-specific reactions we also found an infection-triggered induction of the non-specific activation state of PBMC in the course of primary infection as measured by the intracellular IFN-gamma and IL-4 content of phorbol-12-myristate-13-acetate/ionomycin-stimulated PBMC. This may represent a new mechanism of immune cells of E. bovis-infected calves contributing to ongoing immune reactions.
针对牛艾美耳球虫的细胞免疫反应具有高度特异性，是抵御攻击感染形成保护的关键因素。在本研究中，我们调查了牛艾美耳球虫初次感染和再次感染的犊牛在体外受牛艾美耳球虫裂殖子I抗原刺激后的细胞免疫反应。初次感染伴随着全血样本中IFN-γ和IL-2基因转录的增加，在潜隐期（感染后8 - 12天）达到峰值，随后下降，而IL-4基因转录主要在发病期被诱导。IL-10 mRNA不受牛艾美耳球虫感染的影响。CD4⁺和CD8⁺ T细胞均被确定为IFN-γ基因转录本的来源，而IL-2和IL-4基因转录主要在CD4⁺ T细胞中增强。在感染后8天从回盲肠淋巴结活检分离的淋巴细胞中，以及在感染后第8天和第12天从抗原刺激的外周血单核细胞（PBMC）获得的细胞培养上清液中，也分别发现了IFN-γ转录本和蛋白水平的升高。犊牛的再次感染对外周血或淋巴结来源的淋巴细胞中的IFN-γ和IL-2基因转录均无影响。相反，从引流淋巴结分离的淋巴细胞中IL-4基因转录增加。除了抗原特异性反应外，我们还发现，通过佛波醇-12-肉豆蔻酸酯-13-乙酸盐/离子霉素刺激的PBMC的细胞内IFN-γ和IL-4含量测定，在初次感染过程中还存在感染引发的PBMC非特异性激活状态的诱导。这可能代表了牛艾美耳球虫感染犊牛的免疫细胞参与持续免疫反应的一种新机制。
