单克隆抗体(McAb)与毒素蛋白结合的免疫毒素在体内、外能选择性地杀伤肿瘤细胞,但由于白喉和蓖麻毒素的一条多肽链上有两种活性作用未能分开,理想的强毒性与高特异性的制剂至今尚未问世。B链的两个特点是:(1)使A链得以进入靶细胞,从而使免疫毒素有效地杀伤靶细胞;(2)能与大多数具有受体的细胞结合,从而使免疫毒素在很大程度上对非靶细胞有毒性作用。本文报告白喉毒素(DT)B链经点突变,可阻断结 Monoclonal antibodies (McAbs) toxin-binding immunotoxins selectively kill tumor cells both in vitro and in vivo, but are insensitive to both actives on one of the polypeptide chains of diphtheria and ricin, ideally highly virulent And high-specific formulations have not yet come out. Two features of the B-chain are: (1) allowing the A-chain to enter the target cell so that the immunotoxin effectively targets the target cell; (2) binds to most of the receptor-bearing cells such that the immunotoxin is very large To the extent toxic to non-target cells. This article reports a point mutation in the B chain of diphtheria toxin (DT) that blocks the junction