Gorvel J P, Vivier I, Naquet P, Brekelmans P, Rigal A, Pierres M
Centre de Biochimie et de Biologie Moléculaire du CNRS, Marseille, France.
J Immunol. 1990 Apr 15;144(8):2899-907.
We previously characterized a dimeric, Mr = 115,000, developmentally regulated mouse T cell-activating molecule (THAM). We show in this report that the THAM-specific mAb H194-112 exhibits strong reactivity with several nonlymphoid tissues including polarized enterocytes from small intestine, kidney cortical tubuli, and liver bile ductuli, as well as kidney glomeruli and lung alveoloar pneumocytes. Both the tissue distribution and the structural features of THAM made it likely that this molecule belongs to the ectoenzyme family. This was confirmed by the following experimental evidence: 1) the H194-112+ molecules from enterocyte brush borders (BB) or M14.T thymoma cells were recognized by several antisera specific for intestinal aminopeptidase N (AP-N); 2) mAb H194-112 was found to immunodeplete the AP-N activity from both thymic or enterocyte BB detergent extracts; 3) the hydrophilic, Mr = 115,000 form obtained by papain treatment of thymoma or enterocyte BB could be immunopurified on H194-112 column and exhibited, after hypotonic elution, strong enzymatic activity on the AP-N substrates (i.e., leucyl or alanyl beta-derivatives); 4) mAb H194-112 was found to inhibit the AP-N activity when assayed on alanyl but not leucyl beta-naphthylamide substrate; and 5) preincubation of AP-N with mAb H194-112 prevented the inhibiting effects of bestatin and D,L-methionyl hydroxamate on AP-N activity. These data add a new member to the list of functional ectoenzymatic markers of lymphoid cells (i.e., CD10, CD13, CD26, CD55, and CD73). In view of the known immunomodulating properties of bestatin, one may speculate that the T cell-activating effects of mAb H194-112 is related to an impairment of a surface enzymatic function regulating lymphoid cell activation.
我们之前鉴定了一种二聚体、分子量为115,000、受发育调控的小鼠T细胞激活分子（THAM）。我们在本报告中表明，THAM特异性单克隆抗体H194-112与几种非淋巴组织具有强反应性，包括来自小肠的极化肠上皮细胞、肾皮质小管、肝胆小管，以及肾小球和肺泡肺细胞。THAM的组织分布和结构特征都表明该分子可能属于外切酶家族。以下实验证据证实了这一点：1）肠上皮细胞刷状缘（BB）或M14.T胸腺瘤细胞中的H194-112 +分子被几种针对肠氨肽酶N（AP-N）的抗血清识别；2）发现单克隆抗体H194-112可从胸腺或肠上皮细胞BB去污剂提取物中免疫去除AP-N活性；3）通过木瓜蛋白酶处理胸腺瘤或肠上皮细胞BB获得的亲水性、分子量为115,000的形式可在H194-112柱上进行免疫纯化，在低渗洗脱后，对AP-N底物（即亮氨酰或丙氨酰β-衍生物）表现出强酶活性；4）发现单克隆抗体H194-112在检测丙氨酰但不是亮氨酰β-萘酰胺底物时可抑制AP-N活性；5）AP-N与单克隆抗体H194-112预孵育可防止苯丁抑制素和D，L-甲硫氨酰异羟肟酸对AP-N活性的抑制作用。这些数据为淋巴细胞功能性外切酶标志物（即CD10、CD13、CD26、CD55和CD73）列表增添了一个新成员。鉴于苯丁抑制素已知的免疫调节特性，有人可能推测单克隆抗体H194-112的T细胞激活作用与调节淋巴细胞激活的表面酶功能受损有关。
