中国近交系猪到人异种移植靶抗原研究

THE XENOANTIGENICITY OF CHINESE INBRED- L INE PIGS

目的 研究人血清对近交系猪组织的结合情况及猪组织内 α-半乳糖残基 (α- Gal)的分布。方法 采取近交系中国版纳小耳猪 4头及近交系五指山猪 1头的心、肝、脾、肺、肾、胰、小肠、胸腺、皮肤、淋巴结及各级血管组织 ,分别以中国正常人 A、B、O和 AB型血清及 BSI- B4为一抗或亲和物 ,用亲和免疫组织化学方法观察各型人血清对上述各组织的结合和组织内 α- Gal的分布情况。并用 α-半乳糖基酶 (α- GT)消化后 ,重复上述实验。结果 两种近交系猪组织的血清结合及 α- Gal分布情况相似。A、B、O和 AB型血清与被测两种猪的各部位组织结合无明显差异 ,主要为各级血管内皮细胞及部分实质细胞。BSI- B4与血清结合的部位相似。软骨、外周神经、肌肉未见血清及 BSI- B4结合。经 α- GT消化后 ,人血清和 BSI- B4与两种猪组织的结合反应除少数部位存在差异外 ,反应消失。结论 对猪进行基因改造时可不考虑其抗原强弱及分布问题。α- Gal是近交系猪的主要靶抗原 ,但不排除存在 α- Gal以外的靶抗原 ,通过对近交系猪基因改造克服排斥反应是较好的策略。

Objective The m ajor obstacle in pig to human transplantation is acute and hyperacute rejec- tion(HAR) triggered mainly byα- galactosyl residues(α- Gal) in donor.Since the inbred- line Banna pig(IBNP) and Wuzhishan pig(IWZSP) are highly inbred and may be the potential donor for xenotransplantation,it is im portant to investigate the reaction between human serum and inbred- line pig tissues as well as the distribution ofα- Gal in these tissues.Methods Samples from heart,liver,spleen,lung,kidney,pancreas,sm all intestine,thym us, skin,lym ph node and blood vessels at all levels were collected from four8to11- month- old male IBNPs and one I- WZSP.Affinity- imm unohistochem istry assays were conducted following routine procedures on paraffin sections with normal human sera of blood type A,B,O,AB and BSI- B4(α- Gal specific binding lectin) as the primary anti- bodies or affinity reagents.Sections digested byα- galactosidase were also examined as control.Results Parallel results were obtained from these pig tissues stained against human sera and BSI- B4.There was no significant dif- ference both in the antigens recognized by sera of different blood types or BSI- B4and in the distribution ofα- Gal. The strongestα- Gal positive staining was appeared in vascular endothelial cells at all levels and partial parenchym a cells.However,tissues of cartilage,peripheral nerve and muscle were negative.After digested byα- Galactosi- dase,all sam ples were negative against BSI- B4and human sera exceptfew positions thatshowed differentstaining. Conclusion The distribution of targetantigen is sim ilar in various tissues of the two kinds of pigs.Thoughα- Gal is the major xenoantigen in IBNP and IWZSP,there m ay be some unknown antigens related to pig to hum an trans- plantation..Possibly the level and distribution of antigen expression in pig tissues are not the first affair to be con- sidered,and these pigs should be genetically m odified in order to eliminate rejection in pig to hum an xenotrans- plantation.