Liu Jie, Ruckwardt Tracy J, Chen Man, Johnson Teresa R, Graham Barney S
Vaccine Research Center, NIAID, National Institutes of Health, 40 Convent Dr., Bethesda, MD 20892-3017, USA.
J Virol. 2009 May;83(10):4934-41. doi: 10.1128/JVI.02140-08. Epub 2009 Mar 4.
CD4 T cells have been shown to play an important role in the immunity and immunopathogenesis of respiratory syncytial virus (RSV) infection. We identified two novel CD4 T-cell epitopes in the RSV M and M2 proteins with core sequences M(213-223) (FKYIKPQSQFI) and M2(27-37) (YFEWPPHALLV). Peptides containing the epitopes stimulated RSV-specific CD4 T cells to produce gamma interferon (IFN-gamma), interleukin 2 (IL-2), and other Th1- and Th2-type cytokines in an I-A(b)-restricted pattern. Construction of fluorochrome-conjugated peptide-I-A(b) class II tetramers revealed RSV M- and M2-specific CD4 T-cell responses in RSV-infected mice in a hierarchical pattern. Peptide-activated CD4 T cells from lungs were more activated and differentiated, and had greater IFN-gamma expression, than CD4 T cells from the spleen, which, in contrast, produced greater levels of IL-2. In addition, M(209-223) peptide-activated CD4 T cells reduced IFN-gamma and IL-2 production in M- and M2-specific CD8 T-cell responses to D(b)-M(187-195) and K(d)-M2(82-90) peptides more than M2(25-39) peptide-stimulated CD4 T cells. This correlated with the fact that I-A(b)-M(209-223) tetramer-positive cells responding to primary RSV infection had a much higher frequency of FoxP3 expression than I-A(b)-M2(26-39) tetramer-positive CD4 T cells, suggesting that the M-specific CD4 T-cell response has greater regulatory function. Characterization of epitope-specific CD4 T cells by novel fluorochrome-conjugated peptide-I-A(b) tetramers allows detailed analysis of their roles in RSV pathogenesis and immunity.
已证明CD4 T细胞在呼吸道合胞病毒（RSV）感染的免疫及免疫发病机制中发挥重要作用。我们在RSV的M和M2蛋白中鉴定出两个新的CD4 T细胞表位，其核心序列分别为M(213 - 223)（FKYIKPQSQFI）和M2(27 - 37)（YFEWPPHALLV）。含这些表位的肽段以I - A(b)限制性模式刺激RSV特异性CD4 T细胞产生γ干扰素（IFN - γ）、白细胞介素2（IL - 2）及其他Th1和Th2型细胞因子。荧光染料偶联肽 - I - A(b)Ⅱ类四聚体的构建揭示了RSV感染小鼠中RSV M和M2特异性CD4 T细胞反应呈分层模式。与来自脾脏的CD4 T细胞相比，来自肺脏的肽激活CD4 T细胞更具活性且分化程度更高，IFN - γ表达水平更高，而脾脏来源的CD4 T细胞则产生更高水平的IL - 2。此外，M(209 - 223)肽激活的CD4 T细胞比M2(25 - 39)肽刺激的CD4 T细胞更能降低M和M特异性CD8 T细胞对D(b)-M(187 - 195)和K(d)-M2(82 - 90)肽段反应中的IFN - γ和IL - 2产生。这与以下事实相关：对初次RSV感染产生反应的I - A(b)-M(209 - 223)四聚体阳性细胞中FoxP3表达频率远高于I - A(b)-M2(26 - 39)四聚体阳性CD4 T细胞，表明M特异性CD4 T细胞反应具有更强的调节功能。通过新型荧光染料偶联肽 - I - A(b)四聚体对表位特异性CD4 T细胞进行表征，能够详细分析它们在RSV发病机制和免疫中的作用。
