人白细胞抗原DQ单体型对特发性1型糖尿病免疫病因分型的意义

目的 通过对临床特征、锌转运体8自身抗体（ZnT8A）、分泌干扰素γ的谷氨酸脱羧酶65反应性T细胞（GAD65-IFN-γ-T细胞）检测情况的比较,探讨人白细胞抗原（HLA） DQ单体型对初诊特发性1型糖尿病免疫病因分型的价值.方法 将2000年3月至2011年12月收治的52例自发酮症或酮症酸中毒起病,谷氨酸脱羧酶抗体（GADA）、蛋白酪氨酸磷酸酶抗体（IA-2A）及胰岛素自身抗体（IAA）均阴性,且依赖胰岛素治疗的湖南省汉族新发1型糖尿病患者纳入本研究.放射配体法检测锌转运体8自身抗体（ZnT8A）,酶联免疫斑点技术（ELISPOT）检测GAD65-IFN-γ-T细胞,聚合酶链反应（PCR）直接测序法测定HLA-DQ基因型.将研究对象分为HLA-DQ易感单体型携带组和HLA-DQ易感单体型不携带组,并以1年为间隔随访3年.比较两组起病初期的临床特征、ZnT8A及GAD65-IFN-γ-T细胞检测情况,随访时胰岛自身抗体的变化.两组间计数资料比较采用x2检验.结果 52例初诊特发性1型糖尿病患者中5例ZnT8A阳性,阳性率9.6％;16例ZnT8A阴性且接受GAD65-IFN-γ-T检测的患者中,2例GAD65-IFN-γ-T阳性,阳性率12.5％.与HLA-DQ易感单体型不携带组相比,携带组起病初期酮症程度更严重（Z=-2.84,P＜0.05）,空腹C肽水平更低（x2 =0.38,P＜0.05）.起病初期,携带组中1例患者GAD65-IFN-γ-T细胞检测呈阳性反应（1/5）,而不携带组未检测到该细胞呈阳性患者.随访时,携带组中1例患者ZnT8A和IA-2A由阴转阳（1/18）,不携带组中未有检测到抗体转阳患者.结论 部分特发性1型糖尿病患者体内存在ZnT8A和GAD65-IFN-γ-T细胞；携带HLA-DQ易感单体型的特发性1型糖尿病患者,较不携带者更加具有自身免疫倾向.胰岛自身免疫是部分初诊特发性1型糖尿病的病因,可能通过HLA-DQ单体型介导.

Role of human leukocyte antigen DQ haplotypes for immunoetiologic classification of idiopathic type 1 diabetes

Objective To investigate the role of human leukocyte antigen （HLA） DQ haplotype for immunoetiologic chassification of idiopathic type 1 diabetes by comparison of clinical features,zinc transporter 8 autoantibodies （ZnT8A）,glutamic acid decarboxylase 65 （GAD65）-reactive interferon-γ-secreting T cells （GAD65-IFN-γ-T cells）.Methods Fifty-two patients of Han People of Hunan Province origin with newly onset idiopathic type 1 diabetes were enrolled in this study from March 2000 to December 2011.The criteria for enrolment included： new-onset,unprovoked ketosis or ketoacidosis at onset; negative glutamic acid decarboxylase antibody（GADA）,protein tyrosinephosphatase antibody （IA-2A） and insulin autoantibody（IAA）; permanent insulin deficiency.ZnT8A were detected in all patients with radioligand assay.GAD65-IFN-γ-T cells were tested by enzyme linked immune spot （ELISPOT） in ZnT8A-negative patients.HLA-DQA1 and DQB1 alleles were identified with polymerase chain reaction （PCR） sequencebased genotyping （SBT）.According to the situation of HLA-DQ susceptible haplotypes,patients with HLADQ genotyping were categorized into two groups,and were all visited annually for 3 consecutive years.Comparisons were made between the two groups in their clinical characteristics,ZnT8A and GAD65-IFN-γ-T cell status.Compare of qualitative data between two groups was progressed by using chi-square test.Results In this study group,ZnT8A was positive in 5 cases out of 52 （9.6％）,and GAD65-IFN-γ-T cells were positive in 2 cases out of 16 patients with ZnT8A negative （12.5％）.More severe diabetic ketoacidosis （DKA） （Z =-2.84,P ＜ 0.05） and lower fasting C protein （FCP） levels （x2 =0.38,P ＜ 0.05） at onset were observed in patients with HLA-DQ susceptible haplotypes.During the onset,GAD65-IFN-γ-T cells was positive in 1 patient carrying HLA-DQ susceptible haplotypes and there was none in patients with nonsusceptible HLA-DQ haplotypes.Islet autoantibodies （ZnT8A and IA-2A） turned positive in 1 patient with HLA-DQ susceptible haplotypes（1/18）,while none was observed in patients with non-HLA-DQ susceptible haplotypes during the 3-year visit.Conclusions ZnT8A and GAD65-IFN-γ-T cells exist in some patients with idiopathic type 1 diabetes.The patients with idiopathic type 1 diabetes carry HLA-DQ susceptible haplotypes,compared with those without HLA-DQ haplotypes,present a autoimmune tendency.It implies that islet autoimmunity,to some extent,could be an etiology of idiopathic type 1 diabetes,which is probably mediated by HLA-DQ hapalotype.