流式细胞术鉴定人外周血滤泡辅助性T细胞

目的:用免疫荧光染色和流式细胞术(FCM)鉴定正常人外周血单个核细胞(PBMC)中滤泡辅助性T(Tfh)细胞, 以便对其功能进行进一步研究.方法:密度梯度离心法分离人PBMC, 采用不同荧光素标记的抗CXCR5、 CD4及CD19抗体进行染色FCM分析, 鉴定出表型为CD4+CXCR5+的T细胞亚群.结果:外周血可以检测到CD4+CXCR5+T细胞亚群, 占CD4+T淋巴细胞百分比为(11.09±0.38)%, MFI值为25.78±0.72, 低于B细胞膜表面CXCR表达水平(MFI值为99.6±8.1).结论:健康人外周血存在一定比例的Tfh细胞, 应用FCM可以成功鉴定Tfh细胞, 为进一步研究其功能提供了良好的技术平台.     

PD-L1 在胃癌患者手术前后外周血T 细胞和单核细胞上的表达及意义

目的:检测胃癌患者术前术后外周血细胞表面PD-L1的表达,探讨其表达改变及临床意义。方法:收集44例胃癌患者术前术后和18名健康志愿者外周血标本,流式细胞术检测CD3⁺ CD4⁺ T、CD3⁺ CD8⁺ T 细胞表面PD-1 和PD-L1 以及CD14⁺单核细胞表面PD-L1 的表达。结果:与健康志愿者相比,胃癌患者外周血CD4⁺ T 和CD8⁺ T 细胞表面PD-L1 表达无显著差异[(11.1±6.4)% vs (9.8±5.6)%,P =0.453 2;(13.9±12.0)% vs (12.0±7.1)%,P =0.558 9],而CD14⁺ 单核细胞表面PD-L1 表达水平显著增加[(29.2±16.7)% vs (17.5±9.7)%,P=0.007 3]。但胃癌患者术后CD4+ T 细胞和CD8⁺ T 细胞表面PD-L1 的表达均显著高于术前水平[(15.8±8.2)% vs (11.1±6.4)%,P= 0.001 5;(22.5±13.3)% vs (13.9±12.0)%,P =0.000 2],而术后外周血CD14+单核细胞PD-L1 表达水平并无显著变化[(33.8±17.3)% vs (29.2±16.7)%,P=0.082 8]。同时,胃癌患者手术前后外周血CD4⁺T 和CD8⁺T 细胞表面PD-1的表达无统计学差异[(25.6±9.9)% vs (26.9±8.9)%,P=0.505 5;(26.5±14.6)% vs (29.9±10.4)%,P=0.118 7]。结论:PD-L1 可作为监测原发性胃癌患者的免疫功能和预后评估的有效指标。     

子宫内膜异位症患者外周血CD4~+CD25~+Foxp3~+调节性T细胞的变化

观察子宫内膜异位症患者外周血单个核细胞CD4~+CD25~+Foxp3~+调节性T细胞的数量变化,初步探讨其意义。采用流式细胞术检测20例健康对照者(对照组)及46例子宫内膜异位症患者(疾病组临床r-AFS分期:Ⅰ～Ⅱ期26例,Ⅲ～Ⅳ期20例)外周血单个核细胞(PBMC)中CD4~+CD25~+Foxp3~+调节性T细胞数目,并计算CD4~+CD25~+Foxp3~+调节性T细胞占CD4~+T淋巴细胞的百分率;分析不同分期子宫内膜异位症患者外周血CD4~+CD25~+Foxp3~+调节性T细胞的变化。结果显示,与健康对照组相比,疾病组PBMC中CD4~+CD25~+Foxp3~+Treg占CD4~+T淋巴细胞的百分率及CD4~+CD25~+Foxp3~+Treg绝对数均明显升高(P<0.01,P<0.05);疾病组中,Ⅲ～Ⅳ期的PBMC中CD4~+CD25~+Foxp3~+Treg占CD4~+T淋巴细胞的百分比及CD4~+CD25~+Foxp3~+Treg绝对值较Ⅰ～Ⅱ期均明显升高(P<0.01,P<0.05)。提示子宫内膜异位症患者外周血CD4~+CD25~+Foxp3~+调节性T细胞数目和比例增多,可能存在自身免疫调节功能的紊乱,且与病程发展紧密相关。     

IL-35对慢性阻塞性肺疾病患者Treg/Th17平衡的影响北大核心CSCD

目的:观察IL-35在慢性阻塞性肺疾病(COPD)患者外周血中的表达及其对CD4^(+)CD25^(+)CD127^(dim/-)Treg和辅助性T细胞17(Th17)的调控作用。方法:选取44例COPD患者和25例健康对照者,分离血浆和外周血单个核细胞(PBMC),ELISA检测血浆IL-35水平,流式细胞术检测PBMC中CD4^(+)CD25^(+)CD127^(dim/-)Treg和Th17水平,计算Treg/Th17。重组人IL-35刺激COPD患者PBMC,流式细胞术检测CD4^(+)CD25^(+)CD127^(dim/-)Treg和Th17比例,ELISA检测培养上清中IL-10、IL-17和IL-22水平,RT-PCR检测FoxP3和RORγt mRNA表达。磁力分选COPD患者PBMC中的CD4^(+)CD25^(+)CD127^(dim/-)Treg,重组人IL-35刺激后与自体PBMC共培养,CCK-8检测细胞增殖。结果:与对照组相比,COPD组血浆IL-35水平降低[(108.20±12.13)pg/ml vs(133.30±22.91)pg/ml,t=5.980,P<0.000 1],CD4^(+)CD25^(+)CD127^(dim/-)Treg比例降低[(4.71±1.00)%vs(6.07±1.03)%,t=5.362,P<0.000 1],Th17比例升高[(2.97±0.72)%vs(2.28±0.61)%,t=4.060,P=0.000 1],Treg/Th17降低(1.69±0.60 vs 2.86±0.91,t=6.279,P<0.000 1)。重组人IL-35刺激后,CD4^(+)CD25^(+)CD127^(dim/-)Treg比例升高(P=0.000 2),Treg/Th17升高(P=0.015 0),而Th17比例无明显变化(P=0.391 0),培养上清中IL-10水平升高[(145.10±24.40)pg/ml vs(123.50±24.11)pg/ml,t=4.520,P<0.000 1],而IL-17和IL-22水平均无明显变化(P>0.05),FoxP3 mRNA表达显著升高(1.27±0.19 vs 0.96±0.10,t=7.600,P<0.000 1),而RORγt mRNA表达无明显变化(P=0.447 0)。重组人IL-35刺激COPD患者分选的CD4^(+)CD25^(+)CD127^(dim/-)Treg免疫抑制活性增强。结论:IL-35主要通过提高CD4^(+)CD25^(+)CD127^(dim/-)Treg比例和活性影响Treg/Th17平衡,在COPD过程中可能发挥免疫保护作用。     

滤泡辅助性T细胞(Tfh)和激活B细胞在帕金森病患者外周血中的水平及意义

目的:探讨帕金森病(PD)患者外周血中滤泡辅助性T细胞(Tfh)和激活B细胞的水平变化及临床意义.方法:选择PD患者73人,健康对照25人.PD患者按照Hoehn-Yahr分期法(H-Y)分为Ⅰ～Ⅳ期.检测外周血单个核细胞(PBMC)中CD4+CXCR5+ICOS+Tfh细胞比例和CD83+CD19+B细胞的比例及Bc...     

CD161~+调节性T细胞降低风湿性心脏病大鼠瓣膜损伤的作用及机制

目的探讨CD161~+调节性T细胞(Treg)降低风湿性心脏病大鼠瓣膜损伤的作用及机制。方法流式细胞术分选CD161~-和CD161~+ Treg并进行培养, ELISA检测Treg培养上清液白细胞介素10(IL-10)和转化生长因子β(TGF-β)的含量; A组溶血性链球菌悬液与Freund完全佐剂混合后建立风湿性心脏病大鼠模型,分为对照组、 CD161~- Treg组、 CD161~+ Treg组。处理1周后,收集大鼠的心脏血和二尖瓣瓣膜。流式细胞术检测心脏血单个核细胞滤泡辅助性T(Tfh)细胞、 B细胞和浆细胞比例, HE染色检测瓣膜组织病理变化,免疫组织化学染色法检测瓣膜组织中B细胞和浆细胞数目, ELISA检测血清IL-21水平。结果 CD161~+ Treg分泌IL-10和TGF-β的能力显著高于CD161~-Treg。与注射CD161~- Treg的大鼠相比,注射CD161~+Treg能够显著降低瓣膜组织损伤,减少瓣膜组织B细胞和浆细胞的比例;且CD161~+Treg注射能够减少大鼠血液中Tfh细胞、 B细胞和浆细胞的比例,血清中IL-21含量降低。结论 CD161~+Treg通过抑制Tfh细胞和B细胞增殖分化,降低风湿性心脏病的瓣膜损伤。     

滤泡辅助性T细胞是系统性红斑狼疮潜在的治疗靶标

系统性红斑狼疮(systemic lupus erythematosus,SLE)是一种慢性自身免疫性疾病,其特征是B细胞过度活化产生致病性自身抗体,因而减少抗体产生是治疗SLE疾病的一种方式。滤泡辅助性T细胞(follicular T helper cells,Tfh)是CD4~+T细胞的一个亚群,辅助B细胞分化成长寿命浆细胞产生自身抗核抗体促发SLE疾病。本文就Tfh细胞参与SLE疾病的发展、参与Tfh细胞形成的因素以及Tfh细胞作为SLE强有力的治疗靶标进行概述。     

人滤泡辅助性T细胞(Tfh)上CD226分子的表达格局

目的:用免疫荧光染色和流式细胞术(FCM)分析鉴定人滤泡辅助性T(Tfh)细胞,对外周血和扁桃体来源的Tfh上CD226分子的表达格局进行研究,采用免疫组化染色的方法,检测异位淋巴组织来源的生发中心中CD226分子的表达情况.方法:采用密度梯度离心法分离人外周血PBMC;扁桃腺经研磨、200目滤网过滤获取扁桃腺细胞,对两种细胞采用不同荧光素标记的抗CXCR5、CD4及CD226抗体进行染色和FCM分析.常规制备类风湿性关节炎(RA)关节滑膜活检组织石蜡切片,采用免疫组化的方法分析CD226分子的表达格局.结果:外周血及扁桃腺Tfh细胞上可以检测到CD226分子,外周血Tfh上CD226阳性率为(91.88±0.52%),MFI值为201.49±6.2;扁桃腺Tfh上CD226表达阳性率为(90.81±0.69%),MFI值为230.81±8.4,表达密度稍高于其他CD4+T细胞.RA患者关节滑膜组织可以观察到异位生发中心(G,C),并检测到CD226分子的表达.结论:健康人外周血、扁桃腺及RA患者关节滑膜组织中存在不同比例的Tfh细胞,其膜上CD226分子的表达具有独特的格局,该结果为进一步研究其功能提供了思路.     

儿童癫痫患者T淋巴细胞活化并产生促炎因子

目的检测儿童癫痫患者外周T淋巴细胞活化状态以及细胞因子水平变化。方法选取20名儿童癫痫患者和19名健康对照儿童,采集外周血,分离外周血单个核细胞(PBMC),用细胞膜表面标记抗体流式细胞术检测T淋巴细胞表面共刺激分子CD69、CD25和细胞毒性T淋巴细胞相关蛋白4(CTLA4)的表达,用细胞内因子染色结合流式细胞术检测T细胞细胞因子γ干扰素(IFN-γ)、白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)和IL-17A的表达,利用细胞内因子染色结合流式细胞术检测调节性T淋巴细胞(Treg)表达IL-10的情况。结果与对照组相比,儿童癫痫患者外周血中T淋巴细胞表面高表达共刺激分子CD69、CD25和CTLA4,活化的CD4+T细胞高表达IFN-γ、TNF-α、IL-6和IL-17 A。在儿童癫痫患者高表达IL-10的Treg数目增加。结论儿童癫痫患者外周T淋巴细胞活化并产生细胞因子。     

滤泡辅助性T细胞及其可塑性的研究进展

初始T细胞受到抗原刺激后,在不同细胞因子的调控下,分化成不同的CD4+T细胞亚群,主要包括Th1、Th2、Th17、Treg和Tfh细胞。滤泡辅助性T细胞(follicular helper T cell,Tfh)是一类新的CD4+T细胞亚群,参与生发中心(germinal center,GC)形成,促使B细胞分化成浆细胞和记忆B细胞,进而在产生抗体的过程中发挥着重要作用。研究发现,Tfh细胞与其他辅助性T细胞在表达转录因子和产生细胞因子上具有重叠性,并且具有向其他CD4+T细胞亚群分化的潜能。本文主要综述Tfh细胞分化的相关分子以及表现Tfh细胞可塑性的证据。     

Fetal BM‐derived mesenchymal stem cells promote the expansion of human Th17 cells,but inhibit the production of Th1 cells

Th type 17 (Th17) cells have been identified as a proinflammatory T‐cell subset. Here, we investigated the regulation of human Th17 cells by fetal BM‐derived mesenchymal stem cells (FBM‐MSC). We cocultured FBM‐MSC with human PBMC or CD4⁺ T cells from healthy donors. FBM‐MSC significantly suppressed the proliferation of CD4⁺ T cells stimulated by PHA and recombinant IL‐2. Significantly higher levels of IL‐17 were observed in FBM‐MSC cocultured with either PBMC or CD4⁺ T cells than that in PBMC cultured alone or CD4⁺ T cells cultured alone. Flow cytometry analysis showed that the percentage of Th17 cells in coculture of FBM‐MSC and CD4⁺ T cells was significantly higher than that in CD4⁺ T‐cell cultured alone. FBM‐MSC did not express IL‐17 protein. Consistent with the augmentation of Th17 cells, significantly higher levels of IL‐6 and IL‐1 were observed in coculture of FBM‐MSC and CD4⁺ T cells than that in CD4⁺ T‐cell culture, while the levels of IL‐23 were similar between FBM‐MSC + PBMC coculture and PBMC alone, or FBM‐MSC + CD4⁺ T‐cell and CD4⁺ T‐cell alone. The presence of FBM‐MSC decreased the percentage of Th1 cells, but minimally affected the expansion of CD4⁺CD25⁺ T cells. In conclusion, our data demonstrate for the first time that FBM‐MSC promote the expansion of Th17 cells and decrease IFN‐γ‐producing Th1 cells. These data suggest that IL‐6 and IL‐1, instead of IL‐23, may be partly involved in the expansion of Th17 cells.     

胚胎骨髓来源间充质干细胞对人Th17细胞的免疫调节

背景：众多研究表明间充质干细胞能发挥免疫调节功能,抑制T细胞增殖。 目的：观察胚胎骨髓来源间充质干细胞对人Th17细胞的调节作用。 方法：将人胚胎骨髓间充质干细胞与正常人外周血单个核细胞或CD4⁺ T细胞以1∶10比例共培养4 d,以单个核细胞或CD4⁺T细胞单独培养为对照。应用实时定量PCR检测细胞白细胞介素17 mRNA表达,酶联免疫吸附试验检测细胞上清中白细胞介素17蛋白水平,流式细胞术检测Th17细胞数量。 结果与结论：胚胎骨髓来源间充质干细胞与单个核细胞共培养组白细胞介素17 mRNA表达水平明显高于单个核细胞组(P < 0.01)。与此一致的是,胚胎骨髓来源间充质干细胞与单个核细胞或CD4⁺T细胞共培养组细胞上清中白细胞介素17蛋白水平明显高于单个核细胞组、CD4⁺ T细胞组(P < 0.05,P < 0.01)。胚胎骨髓来源间充质干细胞与CD4⁺ T细胞共培养组Th17细胞数量明显高于CD4⁺ T细胞组(P < 0.01),但胚胎骨髓来源间充质干细胞本身并不表达白细胞介素17。表明胚胎骨髓来源间充质干细胞可促进人Th17细胞增殖。     

外周血循环滤泡辅助性T 细胞及IL-21 在银屑病中的表达及意义

目的:探讨外周血循环滤泡辅助性T 细胞(Follicular helper T cells,Tfh)及相关细胞因子IL-21 在银屑病患者中的表达水平及其与疾病活动度的关系。方法:收集38 例银屑病患者及32 例健康对照者,流式细胞术检测外周血循环CD4+CXCR5+ Tfh 和CD4+ CXCR5+ ICOS+ Tfh 细胞比例以及Th17 细胞比例;ELISA 检测血清IL-21 浓度;分析这些指标间及与银屑病疾病活动度评分PASI 间的相关性。结果:与健康对照者相比,银屑病患者外周血循环CD4+ CXCR5+ Tfh 和CD4+ CXCR5+ ICOS+Tfh 细胞比例更高,血清IL-21 浓度和Th17 细胞比例亦显著高于对照组(P<0.05);IL-21 浓度与CD4+ CXCR5+ Tfh 和CD4+CXCR5+ ICOS+ Tfh 细胞比例均显著正相关,而与Th17 细胞比例间无显著相关性(P>0.05);且CD4+ CXCR5+ ICOS+ Tfh 细胞比例和血清IL-21 与银屑病疾病活动度PASI 评分显著正相关,而CD4+ CXCR5+ Tfh 则与之无显著相关性(P>0.05)。结论:银屑病患者外周血循环Tfh 比例、IL-21 浓度上调与银屑病患者疾病活动度密切相关,提示Tfh 可能参与银屑病的发生发展过程,这一效应可能是通过分泌高水平IL-21 实现;IL-21 浓度与Tfh 细胞比例相关,而与Th17 细胞比例无相关性提示银屑病患者IL-21可能主要由Tfh 细胞分泌。     

Telomere shortening and decreased replicative potential, contrasted by continued proliferation of telomerase-positive CD8+CD28(lo) T cells in patients with systemic lupus erythematosus

To evaluate whether the immune system of systemic lupus erythematosus (SLE) patients shows features of premature aging, we compared telomere length and proliferative potential of SLE peripheral blood mononuclear cells (PBMC) (N = 90) to those of controls (N = 64). SLE samples showed accelerated loss of telomeric DNA (P = 0.00008) and higher levels of senescent (< or =5 kb) telomeric DNA (P = 0.00003). Viability cell counts and CFSE tracking in 6-week-old cell cultures indicated that SLE PBMC (CD8+ and CD4+ T cells) underwent fewer mitotic cycles and had shorter telomeres than controls (P = 0.04). However, a CD8(+)CD28(lo) T cell subset expanded preferentially in SLE-derived bulk cultures (P = 0.0009), preserved telomeric DNA (P = 0.01 vs entire CD8+), and displayed telomerase activity [2.1 telomerase arbitrary units (TAU) vs 0.5 TAU in CD8+CD28(hi) cells and 0.3 TAU in bulk PBMC; P = 0.05]. These T cell anomalies could be due to chronic in vivo stimulation of the immune system and may contribute to the immune dysregulation found in SLE.     

Human blood CXCR5(+)CD4(+) T cells are counterparts of T follicular cells and contain specific subsets that differentially support antibody secretion

Although a fraction of human blood memory CD4(+) T cells expresses chemokine (C-X-C motif) receptor 5 (CXCR5), their relationship to T follicular helper (Tfh) cells is not well established. Here we show that human blood CXCR5(+)CD4(+) T cells share functional properties with Tfh cells and appear to represent their circulating memory compartment. Blood CXCR5(+)CD4(+) T cells comprised three subsets: T helper 1 (Th1), Th2, and Th17 cells. Th2 and Th17 cells within CXCR5(+), but not within CXCR5(-), compartment efficiently induced naive B cells to produce immunoglobulins via interleukin-21 (IL-21). In contrast, Th1 cells from both CXCR5(+) and CXCR5(-) compartments lacked the capacity to help B cells. Patients with juvenile dermatomyositis, a systemic autoimmune disease, displayed a profound skewing of blood CXCR5(+) Th cell subsets toward Th2 and Th17 cells. Importantly, the skewing of subsets correlated with disease activity and frequency of blood plasmablasts. Collectively, our study suggests that an altered balance of Tfh cell subsets contributes to human autoimmunity.     

美沙拉嗪对DSS诱导小鼠溃疡性结肠炎模型Th1、Th17及Treg细胞亚群的影响

 目的:观察葡聚糖硫酸钠（DSS）诱导小鼠溃疡性结肠炎（UC）模型中辅助性T细胞（Th1、Th17亚群）及调节性T细胞（Treg）细胞亚群的变化,探讨美沙拉嗪（MSLZ）治疗UC的免疫学机制。方法: 采用流式细胞分析术检测DSS诱导的小鼠UC模型结肠组织及外周血单个核细胞中白细胞介素17（IL-17）、γ-干扰素（IFN-γ）及核转录因子Foxp3的表达,并检测MSLZ预治疗对小鼠UC 模型Th1、Th17和Treg亚群的影响。结果: 在DSS诱导的小鼠UC模型中,其外周血单个核细胞（PBMC）中CD3+T细胞高表达IL-17、IFN-γ及Foxp3,肠黏膜单个核细胞（LPMC）中CD3+T细胞高表达IFN-γ和Foxp3,但IL-17的表达与对照组无差异。进一步发现UC模型小鼠LPMC中Th17、Th1和Treg均显著高于对照组,但PBMC中只有Treg高于对照组。MSLZ预治疗能显著下调UC 模型小鼠PBMC和LPMC中Th17、Th1和Treg细胞亚群。结论: DSS诱导的小鼠 UC模型中CD4+T细胞亚群Th1、Th17及Treg细胞显著升高,提示CD4+T细胞亚群在UC发病中起重要作用,美沙拉嗪可能通过调节Th1、Th17及Treg细胞亚群发挥抗炎及治疗UC作用。     

调节性T细胞和人类系统性红斑狼疮关系的研究进展

系统性红斑狼疮(SLE)是一种自身免疫系统疾病、可累及全身各个系统、脏器和组织,调节性T细胞(Tr)在其发生发展中发挥了重要的作用.目前所知的Tr具有免疫抑制的作用,包括两个亚群--CD4+Tr(CD4+CD25+Tr、Tr1和Th3细胞)和CD8+Tr(Ts细胞和CD8+CD25+T细胞).全面了解Tr和人类SLE的关系是在此领域发展新的免疫学治疗方法的基础.     

滤泡辅助性T细胞的研究进展

滤泡辅助性T细胞（Tfh）是最近发现的CD4^＋辅助性T淋巴细胞亚群,其作用是辅助B细胞的抗体产生.其发生、分化和功能均独立于以往的Th1、Th2和Th17细胞,是体液免疫反应的关键.转录因子Bcl-6和Blimp-1在Tfh细胞的分化中起着关键的、相互拮抗的作用,调节趋化因子受体、表面分子和细胞因子等表达,这些因子对Tfh细胞募集和B细胞辅助功能非常重要.     

Interferon-α regulates abnormally increased expression of RSAD2 in Th17 and Tfh cells in systemic lupus erythematosus patients

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that often involves abnormal activation of regulatory IFN genes and regulation of B cells by CD4⁺ T cells. Radical S-adenosyl methionine domain containing 2 (RSAD2) is a viral suppressor protein regulated by type I IFN, and it has been proven to play an important regulatory role in SLE. However, the mechanism by which RSAD2 participates in the pathogenesis of SLE is unclear. In this study, we observed higher expression levels of RSAD2 in CD4⁺ T-cell subsets from the peripheral blood of SLE patients than in those from healthy controls by bioinformatics analysis and validation experiments. We analyzed the expression of RSAD2 in CD4⁺ T cells of patients with SLE and other autoimmune diseases. In addition, we found that the expression of RSAD2 in CD4⁺ T cells might be regulated by IFN-α, and RSAD2 significantly affected the differentiation of Th17 cells and T follicular helper (Tfh) cells. Our findings underlined that RSAD2 may promote B-cell activation by promoting the differentiation of Th17 and Tfh cells in SLE patients, a process that is regulated by IFN-α.     

Regulatory T cells and T helper 17 cells in viral infection

CD4⁺ T cells are the central element of the adaptive immune responses and protect the body from a variety of pathogens. Starting from naive cells, CD4⁺ T cells can differentiate into various effector cell subsets with specialized functions including T helper (Th) 1, Th2, Th17, regulatory T (Treg) and T follicular helper (Tfh) cells. Among them, Tregs and Th17 cells show a strong plasticity allowing the functional adaptation to various physiological and pathological environments during immune responses. Although they are derived from the same precursor cells and their differentiation pathways are interrelated, the terminally differentiated cells have totally opposite functions. Studies have shown that Tregs and Th17 cells have rather complex interplays in viral infection: Th17 cells may contribute to immune activation and disease progression while Tregs may inhibit this process and play a key role in the maintenance of immune homoeostasis, possibly at the cost of compromised viral control. In this review, we take respiratory syncytial virus (RSV), hepatitis B virus (HBV)/hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections as examples to discuss these interplays and their impacts on disease progression in viral infection.