Functional study of the different haplotypes cDNA in the coding region of CⅡTA gene

Objective To study the function of 4 different haplotypes cDNA which are constructed by two non-homonymy single nueleotide polymorphism (SNP) sites C19170G (Leu45Val) and C30799G (Ala500Gly) in the coding region of human CⅡTA gene. Methods HeLa cells were transfeeted with eu-karyotic expression vectors containing four different haplotypes cDNA. C Ⅱ TA mRNA and HLA classⅡanti-gen (HLA-DR, DP, DQ) were respectively detected by RT-PCR and indirect cell immunofluoreseence tech-nique in the untransfected and transfeeted with four eukaryotic expression vectors and empty vectors HeLa cells. The quantity of HLA classⅡ antigen were analyzed by flow eytometry. Results No expression of CⅡTA mRNA and HLA class Ⅱ antigen were observed on original HeLa cells and empty vector transfected cells. CⅡTA mRNA expression was emerged, and the expression of HLA class Ⅱ antigen were observed in the HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA. And there were not significantly different with the levels of HLA class Ⅱ antigen expression among HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA ( P > 0.05 ). Con-dusion The SNP of Chinese at the sites C19170G(Leu45Val) and C30799G(Ala500Gly) in the coding site of C Ⅱ TA gene did not influence capability of CⅡTA trans-aetivating HLA class Ⅱgene expression.     

Functional study of the different haplotypes cDNA in the coding region of CⅡTA gene

Objective To study the function of 4 different haplotypes cDNA which are constructed by two non-homonymy single nueleotide polymorphism (SNP) sites C19170G (Leu45Val) and C30799G (Ala500Gly) in the coding region of human CⅡTA gene. Methods HeLa cells were transfeeted with eu-karyotic expression vectors containing four different haplotypes cDNA. C Ⅱ TA mRNA and HLA classⅡanti-gen (HLA-DR, DP, DQ) were respectively detected by RT-PCR and indirect cell immunofluoreseence tech-nique in the untransfected and transfeeted with four eukaryotic expression vectors and empty vectors HeLa cells. The quantity of HLA classⅡ antigen were analyzed by flow eytometry. Results No expression of CⅡTA mRNA and HLA class Ⅱ antigen were observed on original HeLa cells and empty vector transfected cells. CⅡTA mRNA expression was emerged, and the expression of HLA class Ⅱ antigen were observed in the HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA. And there were not significantly different with the levels of HLA class Ⅱ antigen expression among HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA ( P > 0.05 ). Con-dusion The SNP of Chinese at the sites C19170G(Leu45Val) and C30799G(Ala500Gly) in the coding site of C Ⅱ TA gene did not influence capability of CⅡTA trans-aetivating HLA class Ⅱgene expression.     

Functional study of the different haplotypes cDNA in the coding region of CⅡTA gene

Objective To study the function of 4 different haplotypes cDNA which are constructed by two non-homonymy single nueleotide polymorphism (SNP) sites C19170G (Leu45Val) and C30799G (Ala500Gly) in the coding region of human CⅡTA gene. Methods HeLa cells were transfeeted with eu-karyotic expression vectors containing four different haplotypes cDNA. C Ⅱ TA mRNA and HLA classⅡanti-gen (HLA-DR, DP, DQ) were respectively detected by RT-PCR and indirect cell immunofluoreseence tech-nique in the untransfected and transfeeted with four eukaryotic expression vectors and empty vectors HeLa cells. The quantity of HLA classⅡ antigen were analyzed by flow eytometry. Results No expression of CⅡTA mRNA and HLA class Ⅱ antigen were observed on original HeLa cells and empty vector transfected cells. CⅡTA mRNA expression was emerged, and the expression of HLA class Ⅱ antigen were observed in the HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA. And there were not significantly different with the levels of HLA class Ⅱ antigen expression among HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA ( P > 0.05 ). Con-dusion The SNP of Chinese at the sites C19170G(Leu45Val) and C30799G(Ala500Gly) in the coding site of C Ⅱ TA gene did not influence capability of CⅡTA trans-aetivating HLA class Ⅱgene expression.     

Functional study of the different haplotypes cDNA in the coding region of CⅡTA gene

Objective To study the function of 4 different haplotypes cDNA which are constructed by two non-homonymy single nueleotide polymorphism (SNP) sites C19170G (Leu45Val) and C30799G (Ala500Gly) in the coding region of human CⅡTA gene. Methods HeLa cells were transfeeted with eu-karyotic expression vectors containing four different haplotypes cDNA. C Ⅱ TA mRNA and HLA classⅡanti-gen (HLA-DR, DP, DQ) were respectively detected by RT-PCR and indirect cell immunofluoreseence tech-nique in the untransfected and transfeeted with four eukaryotic expression vectors and empty vectors HeLa cells. The quantity of HLA classⅡ antigen were analyzed by flow eytometry. Results No expression of CⅡTA mRNA and HLA class Ⅱ antigen were observed on original HeLa cells and empty vector transfected cells. CⅡTA mRNA expression was emerged, and the expression of HLA class Ⅱ antigen were observed in the HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA. And there were not significantly different with the levels of HLA class Ⅱ antigen expression among HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA ( P > 0.05 ). Con-dusion The SNP of Chinese at the sites C19170G(Leu45Val) and C30799G(Ala500Gly) in the coding site of C Ⅱ TA gene did not influence capability of CⅡTA trans-aetivating HLA class Ⅱgene expression.     

Functional study of the different haplotypes cDNA in the coding region of CⅡTA gene

Objective To study the function of 4 different haplotypes cDNA which are constructed by two non-homonymy single nueleotide polymorphism (SNP) sites C19170G (Leu45Val) and C30799G (Ala500Gly) in the coding region of human CⅡTA gene. Methods HeLa cells were transfeeted with eu-karyotic expression vectors containing four different haplotypes cDNA. C Ⅱ TA mRNA and HLA classⅡanti-gen (HLA-DR, DP, DQ) were respectively detected by RT-PCR and indirect cell immunofluoreseence tech-nique in the untransfected and transfeeted with four eukaryotic expression vectors and empty vectors HeLa cells. The quantity of HLA classⅡ antigen were analyzed by flow eytometry. Results No expression of CⅡTA mRNA and HLA class Ⅱ antigen were observed on original HeLa cells and empty vector transfected cells. CⅡTA mRNA expression was emerged, and the expression of HLA class Ⅱ antigen were observed in the HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA. And there were not significantly different with the levels of HLA class Ⅱ antigen expression among HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA ( P > 0.05 ). Con-dusion The SNP of Chinese at the sites C19170G(Leu45Val) and C30799G(Ala500Gly) in the coding site of C Ⅱ TA gene did not influence capability of CⅡTA trans-aetivating HLA class Ⅱgene expression.     

Functional study of the different haplotypes cDNA in the coding region of CⅡTA gene

Objective To study the function of 4 different haplotypes cDNA which are constructed by two non-homonymy single nueleotide polymorphism (SNP) sites C19170G (Leu45Val) and C30799G (Ala500Gly) in the coding region of human CⅡTA gene. Methods HeLa cells were transfeeted with eu-karyotic expression vectors containing four different haplotypes cDNA. C Ⅱ TA mRNA and HLA classⅡanti-gen (HLA-DR, DP, DQ) were respectively detected by RT-PCR and indirect cell immunofluoreseence tech-nique in the untransfected and transfeeted with four eukaryotic expression vectors and empty vectors HeLa cells. The quantity of HLA classⅡ antigen were analyzed by flow eytometry. Results No expression of CⅡTA mRNA and HLA class Ⅱ antigen were observed on original HeLa cells and empty vector transfected cells. CⅡTA mRNA expression was emerged, and the expression of HLA class Ⅱ antigen were observed in the HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA. And there were not significantly different with the levels of HLA class Ⅱ antigen expression among HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA ( P > 0.05 ). Con-dusion The SNP of Chinese at the sites C19170G(Leu45Val) and C30799G(Ala500Gly) in the coding site of C Ⅱ TA gene did not influence capability of CⅡTA trans-aetivating HLA class Ⅱgene expression.     

Functional study of the different haplotypes cDNA in the coding region of CⅡTA gene

Objective To study the function of 4 different haplotypes cDNA which are constructed by two non-homonymy single nueleotide polymorphism (SNP) sites C19170G (Leu45Val) and C30799G (Ala500Gly) in the coding region of human CⅡTA gene. Methods HeLa cells were transfeeted with eu-karyotic expression vectors containing four different haplotypes cDNA. C Ⅱ TA mRNA and HLA classⅡanti-gen (HLA-DR, DP, DQ) were respectively detected by RT-PCR and indirect cell immunofluoreseence tech-nique in the untransfected and transfeeted with four eukaryotic expression vectors and empty vectors HeLa cells. The quantity of HLA classⅡ antigen were analyzed by flow eytometry. Results No expression of CⅡTA mRNA and HLA class Ⅱ antigen were observed on original HeLa cells and empty vector transfected cells. CⅡTA mRNA expression was emerged, and the expression of HLA class Ⅱ antigen were observed in the HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA. And there were not significantly different with the levels of HLA class Ⅱ antigen expression among HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA ( P > 0.05 ). Con-dusion The SNP of Chinese at the sites C19170G(Leu45Val) and C30799G(Ala500Gly) in the coding site of C Ⅱ TA gene did not influence capability of CⅡTA trans-aetivating HLA class Ⅱgene expression.     

Functional study of the different haplotypes cDNA in the coding region of CⅡTA gene

Objective To study the function of 4 different haplotypes cDNA which are constructed by two non-homonymy single nueleotide polymorphism (SNP) sites C19170G (Leu45Val) and C30799G (Ala500Gly) in the coding region of human CⅡTA gene. Methods HeLa cells were transfeeted with eu-karyotic expression vectors containing four different haplotypes cDNA. C Ⅱ TA mRNA and HLA classⅡanti-gen (HLA-DR, DP, DQ) were respectively detected by RT-PCR and indirect cell immunofluoreseence tech-nique in the untransfected and transfeeted with four eukaryotic expression vectors and empty vectors HeLa cells. The quantity of HLA classⅡ antigen were analyzed by flow eytometry. Results No expression of CⅡTA mRNA and HLA class Ⅱ antigen were observed on original HeLa cells and empty vector transfected cells. CⅡTA mRNA expression was emerged, and the expression of HLA class Ⅱ antigen were observed in the HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA. And there were not significantly different with the levels of HLA class Ⅱ antigen expression among HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA ( P > 0.05 ). Con-dusion The SNP of Chinese at the sites C19170G(Leu45Val) and C30799G(Ala500Gly) in the coding site of C Ⅱ TA gene did not influence capability of CⅡTA trans-aetivating HLA class Ⅱgene expression.     

Functional study of the different haplotypes cDNA in the coding region of CⅡTA gene

Objective To study the function of 4 different haplotypes cDNA which are constructed by two non-homonymy single nueleotide polymorphism (SNP) sites C19170G (Leu45Val) and C30799G (Ala500Gly) in the coding region of human CⅡTA gene. Methods HeLa cells were transfeeted with eu-karyotic expression vectors containing four different haplotypes cDNA. C Ⅱ TA mRNA and HLA classⅡanti-gen (HLA-DR, DP, DQ) were respectively detected by RT-PCR and indirect cell immunofluoreseence tech-nique in the untransfected and transfeeted with four eukaryotic expression vectors and empty vectors HeLa cells. The quantity of HLA classⅡ antigen were analyzed by flow eytometry. Results No expression of CⅡTA mRNA and HLA class Ⅱ antigen were observed on original HeLa cells and empty vector transfected cells. CⅡTA mRNA expression was emerged, and the expression of HLA class Ⅱ antigen were observed in the HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA. And there were not significantly different with the levels of HLA class Ⅱ antigen expression among HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA ( P > 0.05 ). Con-dusion The SNP of Chinese at the sites C19170G(Leu45Val) and C30799G(Ala500Gly) in the coding site of C Ⅱ TA gene did not influence capability of CⅡTA trans-aetivating HLA class Ⅱgene expression.     

Functional study of the different haplotypes cDNA in the coding region of CⅡTA gene

Objective To study the function of 4 different haplotypes cDNA which are constructed by two non-homonymy single nueleotide polymorphism (SNP) sites C19170G (Leu45Val) and C30799G (Ala500Gly) in the coding region of human CⅡTA gene. Methods HeLa cells were transfeeted with eu-karyotic expression vectors containing four different haplotypes cDNA. C Ⅱ TA mRNA and HLA classⅡanti-gen (HLA-DR, DP, DQ) were respectively detected by RT-PCR and indirect cell immunofluoreseence tech-nique in the untransfected and transfeeted with four eukaryotic expression vectors and empty vectors HeLa cells. The quantity of HLA classⅡ antigen were analyzed by flow eytometry. Results No expression of CⅡTA mRNA and HLA class Ⅱ antigen were observed on original HeLa cells and empty vector transfected cells. CⅡTA mRNA expression was emerged, and the expression of HLA class Ⅱ antigen were observed in the HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA. And there were not significantly different with the levels of HLA class Ⅱ antigen expression among HeLa cells transfected with eukaryotic expression vectors containing four different haplotypes cDNA ( P > 0.05 ). Con-dusion The SNP of Chinese at the sites C19170G(Leu45Val) and C30799G(Ala500Gly) in the coding site of C Ⅱ TA gene did not influence capability of CⅡTA trans-aetivating HLA class Ⅱgene expression.     

088 MHCⅡ类分子反式激活因子（CⅡTA）的研究进展

ＭＨＣⅡ分子反式激活蛋白（ＣＴＡ，ｃｌａｓｓⅡ 的发现是近年来国际免疫学研究的一项重大突破，ＣⅡＴＡ及其突变体在免疫调节和免疫治疗中具有诱人前景。本文对ＣⅡＴＡ的结构，功能及其反式激活ＭＨＣⅡ类分子的机制作一综述，并对ＣⅡＴＡ及其突一的应用前景作一简要介绍。     

广东汉族人群HLA Ⅰ、Ⅱ基因多态性及单倍型分析

目的 检测广东汉族人群HLA-A、B、Cw、DRB1基因频率，分析该人群HLAⅠ、Ⅱ等位基因多态性及其单倍型特点。方法 骨髓移植供者160人，抗凝血提取DNA，半量全自动聚合酶链反应-单链构象多态分型检测HLA-A、B、Cw、DRB1基因型。结果 在低分辨水平分别检出HLA-A、B、Cw及DRB1等位基因12、23、11、13个。统计分析呈现显著连锁不平衡的HLA-A-B单倍型9个，B-Cw单倍型20个，A-Cw单倍型7个，HLA-A-DRB1单倍型8个，B-DRB1单倍型9个，Cw-DRB1单倍型10个。结论 广东汉族群体HLA-基因具有较为丰富的多态性，其双座位连锁不平衡单倍型具有地区性遗传特征。     

小鼠pIV启动子调控CⅡTA突变体重组腺病毒表达选择性抑制MHC Ⅱ类分子的表达

目的：观察受CⅡTA-pIV启动子驱动的MHCⅡ类分子反式激活因子突变体（CⅡTAm）重组腺病毒对MHCⅡ类分子表达的选择性抑制作用，并探讨其相关机制。方法：构建了N-端酸性氨基酸区缺失了118aa的CⅡTA突变体及其CⅡTA-pIV启动子驱动的重组腺病毒Ad-pⅣ-CⅡTAm，将Ad-pIV-CⅡTAm或对照腺病毒Ad-GFP感染小鼠内皮细胞株SVEC细胞和转染巨噬细胞株J774细胞，并以IFN-γ刺激。用RT-PCR检测野生型和突变型CⅡTA mRNA的表达，用流式细胞术检测MHCⅡ类分子在细胞表面的表达。结果：成功构建CⅡTA-pIV启动子调控下的CⅡTA突变体基因重组腺病毒表达载体Ad-pIV-CⅡTAm；该腺病毒介导的CⅡTA突变体mRNA在SVEC和J774细胞内的表达受到IFN-7的上调，同时抑制这些细胞上诱导型和组成型MHCⅡ类分子的表达。结论：Ad-pIV-CⅡTAm重组腺病毒是一种WN-γ调控型表达载体，可有效地抑制受感染细胞上MHCⅡ类分子的表达。     

MHCⅡ类分子反式激活因子(CⅡTA)的研究进展

MHCⅡ类分子反式激活蛋白 (CⅡTA ,classⅡtransactivator)的发现是近年来国际免疫学研究的一项重大突破 ,CⅡTA及其突变体在免疫调节和免疫治疗中具有诱人前景。本文对CⅡTA的结构、功能及其反式激活MHCⅡ类分子的机制作一综述 ,并对CⅡTA及其突变体的应用前景作一简要介绍。     

CⅡTA锤头状核酶的克隆及其体外活性

通过CⅡTA核酶抑制HeLa细胞表面MHC Ⅱ类分子的表达.设计并合成针对人类CⅡTA的核酶Rz464,通过体外转录和切割实验鉴定其活性.将Rz464亚克隆到真核表达载体pIRES2-EGFP(pRz464),并稳定转染HeLa细胞株,流式细胞术检测MHC Ⅱ类抗原表达,RT-PCR检测CⅡTA mRNA水平.结果表明,Rz464与CⅡTA靶序列体外切割产物电泳见预期切割条带.pRz464+HeLa细胞与对照组比较,HLA-DR、DP、DQ抗原诱导型表达分别降低了79.21%、90.31%及48.30%;同时CⅡTA的诱导型mRNA含量明显减少.Rz464通过切割CⅡTA mRNA,进而阻止了后者调控的MHC Ⅱ类分子的表达.     

基于标签单核苷酸多态性单倍型和单倍域的构建及其在关联研究中的应用

人类基因组中单倍型(haplotype)和单倍域(haplotype block)的结构提供了人类进化的宝贵信息,并成为发现人类复杂疾病易感基因的有效策略。一个单倍域可分割成多个具有有限单倍型多样性的离散的区域,代表每个区域结构特征的少量标签单核苷酸多态性(tag single nucleotide polymorphism,tSNP)可使绝大部分单倍型相互区分开来。因此,标签SNP在单倍型和单倍域的构建和关联研究中具有重要地位。构建单倍型和单倍域的方法分为两类,分别是基于大家系中基因分型数据和基于统计学的算法。通过系统回顾几种单倍型和单倍域的构建方法,了解它们在不同的疾病模型或根据不同的分割标准,进行关联研究的检验效能,客观评价每种方法的优、缺点、应用前景及其在关联研究中的应用。随着国际人类基因组单倍型图的完成和单倍型构建统计学运算规则的完善,融合数学、物理学、计算机科学等学科的单倍型构建方法将对人类遗传学、复杂疾病易感基因的定位和克隆鉴定等生命科学的相关领域产生深远的影响。     

ESR1基因单核苷酸多态性及单倍型与精神分裂症的关联研究

目的 探索雌激素受体1 (estrogen receptor 1,ESR1)基因rs2234693、rs9340799和rs3798759位点单核苷酸多念性(single nucleotide polymorphisms,SNPs)及其单倍型与精神分裂症(schizophrenia,SZ)发病之间的相关性.方法 应用聚合酶链反应-限制性片段长度多态性技术对333例SZ患者和315名正常对照rs2234693、rs9340799和rs3798759位点进行基因分型,应用x2检验对SZ组和对照组等位基因、基因型和单倍型频率进行分析.结果 rs2234693、rs9340799位点两组间基因型频率及等位基因分布差异均无统计学意义(P＞0.05).SZ组rs3798759位点GG基因型频率及G等位基因频率均高于健康对照组(P＜0.01).性别分层分析提示,女性SZ患者rs3798759位点TG、GG基因型频率及G等位基因频率均高于健康女性(P＜0.05).单倍型C-A-G和C-G-G在SZ组的分布频率高于对照组(P＜0.05).结论 rs3798759位点突变可能为女性精神分裂症发生的风险因子,C-A-G和C-G-G单倍型可能为精神分裂症的遗传风险单倍型.     

CⅡTA M1-RNA对MHCⅡ类分子表达的抑制作用

目的探讨MHCⅡ类分子转录激活因子（CⅡTA）的M1-RNA对细胞表面MHCⅡ类分子表达的抑制。方法M1-RNA是核糖核酸酶P的催化活性单位，设计并克隆针对CⅡTA第452、629位点的M1-RNA（分别为M1-452-GS、M1-629-GS）及其相应的CⅡTA靶基因，分别插入pUC19、pGEM-7zf（＋）载体，进行细胞外切割活性筛选。将细胞外切割作甩明显的M1-629-GS亚克隆入psNAV载体（psNAV-M1-629-GS，pA629）并稳定转染ECV304细胞株，流式细胞术检测经典的MHCⅡ（HLA-DR、-DP、-DQ）类抗原表达，RT-PCR检测CⅡTA的mRNA水平。结果pA629阳性ECV304细胞株与对照组比较，HLA-DR、-DP抗原表达分别降低了89．21％及92．31％；同时CⅡTA的mRNA含量降低（P〈0．05）。结论CⅡTA的M1-RNA（M1-629-GS）降低了自身mRNA含量，从而阻止其调控的MHCⅡ类分子的表达。     

反义CⅡTA基因转移对MHCⅡ类分子表达的抑制作用

主要组织相容性复合体 (ＭＨＣ)Ⅱ类分子可将外源性抗原提呈给Ｔ辅助细胞。ＭＨＣⅡ类的组成型表达仅限于“专职性”抗原提呈细胞 ,但细胞因子如ＩＦＮ γ可引起诱导型Ⅱ类分子表达。无论是组成型还是诱导型Ⅱ类分子表达 ,ＭＨＣⅡ类分子转录活化因子 (ＣⅡＴＡ)都是绝对必需的。近年的研究提示ＣⅡＴＡ是控制ＭＨＣⅡ类基因表达的主宰调节者 ,决定着ＭＨＣⅡ类分子的存在与否及表达程度。因此 ,ＣⅡＴＡ是干预ＭＨＣⅡ类分子抗原提呈作用的理想靶点。反义技术是基因治疗中很有前途的策略 ,用反义核酸抑制靶基因的转录或翻译 ,从而阻断或减…     

腺病毒介导CⅡTA突变体基因转移抑制MHCⅡ类分子表达的体外研究

目的:构建携带小鼠MHCⅡ类分子反式激活因子(MHC class Ⅱ molecule transactivator,CⅡTA)突变体基因的腺病毒,并观察腺病毒介导该基因的表达情况以及表达产物的体外功能.方法:采用常规分子生物学方法从IFN-γ诱导后的BALB/c小鼠腹腔巨噬细胞中获得Ⅳ型CIITAcDNA;利用重叠延伸PCR法构建CIITA突变体基因,并克隆入表达载体pIRES;采用pAdEasy-1系统获得具有感染能力的、携带CIITA突变体基因的缺陷型重组腺病毒(Ad-CIITAm)和空载对照病毒(Ad-GFP),并经大量扩增、纯化及滴度测定;将Ad-CⅡTAm和Ad-GFP分别感染HeLa细胞和Raji细胞,流式细胞术观察对诱导型和组成型HLA-DR分子表达的影响.结果:成功克隆了小鼠CⅡTA突变体基因,并构建了携带小鼠CⅡTA突变体基因的重组腺病毒Ad-CⅡTAm;经流式细胞术证实感染Ad-CⅡTAm的Hela和Raji细胞较感染Ad-GFP的细胞,其表面HLA-DR分子的表达均受到明显的抑制.结论:本实验证实了重组腺病毒介导表达的小鼠CⅡTA突变体在体外能够有效地抑制MHCⅡ类分子的表达.