天然及去糖基化蓖麻毒素A链免疫毒素在体外和体内被小鼠肝脏实质细胞和非实质细胞摄取的情况。

Uptake of native and deglycosylated ricin A-chain immunotoxins by mouse liver parenchymal and non-parenchymal cells in vitro and in vivo.

作者信息

Blakey D C, Skilleter D N, Price R J, Thorpe P E

机构信息

Drug Targeting Laboratory, Imperial Cancer Research Fund, London, U.K.

出版信息

Biochim Biophys Acta. 1988 Feb 22;968(2):172-8. doi: 10.1016/0167-4889(88)90005-5.

DOI:10.1016/0167-4889(88)90005-5

PMID:3257705

Abstract

The therapeutic activity of ricin A-chain immunotoxins is undermined by their rapid clearance from the bloodstream of animals by the liver. This uptake has generally been attributed to recognition of the mannose-terminating oligosaccharides present on ricin A-chain by receptors present on the non-parenchymal (Kupffer and sinusoidal) cells of the liver. However, we demonstrate here that, in the mouse, the liver uptake of a ricin A-chain immunotoxin occurs in both parenchymal and non-parenchymal cells in equal amounts. This is in contrast to the situation in the rat, where uptake of the immunotoxin is predominantly by the non-parenchymal cells. Recognition of sugar residues on the A-chain portion of the immunotoxin plays an important role in the liver uptake by both cell types in both species. However it is not the only mechanism since, firstly, an immunotoxin containing ricin A-chain which had been effectively deglycosylated with metaperiodate and cyanoborohydride was still trapped to a significant extent by hepatic non-parenchymal cells after it was injected into mice. Secondly, deglycosylation, while eliminating uptake of the free A-chain by parenchymal and non-parenchymal cells in vitro, only reduced the uptake of an immunotoxin by either cell type by about half. Thirdly, the addition of excess D-mannose or L-fucose inhibited the uptake of free A-chain by mouse liver cell cultures by more than 80% but only inhibited the uptake of the native A-chain immunotoxin by about half and had little effect on the uptake of the deglycosylated ricin A-chain immunotoxin. Recognition of the antibody portion of the immunotoxin by liver cells seems improbable, since antibody alone or an antibody-bovine serum albumin conjugate were not taken up in appreciable amounts by the cultures. Possibly attachment of the A-chain to the antibody exposes sites on the A-chain that are recognised by liver cells in vitro and in vivo.

摘要

蓖麻毒素A链免疫毒素的治疗活性因其在动物血液中被肝脏快速清除而受到削弱。这种摄取通常被认为是肝脏非实质细胞（库普弗细胞和窦状隙细胞）上的受体识别了蓖麻毒素A链上存在的甘露糖末端寡糖。然而，我们在此证明，在小鼠中，蓖麻毒素A链免疫毒素在肝脏实质细胞和非实质细胞中的摄取量相等。这与大鼠的情况相反，在大鼠中，免疫毒素的摄取主要发生在非实质细胞中。免疫毒素A链部分的糖残基识别在两种物种的两种细胞类型的肝脏摄取中都起着重要作用。然而，这不是唯一的机制，因为首先，用高碘酸盐和氰基硼氢化钠有效去糖基化的含蓖麻毒素A链的免疫毒素在注入小鼠后，仍被肝脏非实质细胞大量截留。其次，去糖基化虽然消除了游离A链在体外被实质细胞和非实质细胞的摄取，但仅使两种细胞类型对免疫毒素的摄取减少了约一半。第三，添加过量的D-甘露糖或L-岩藻糖可使小鼠肝细胞培养物对游离A链的摄取抑制超过80%，但仅使天然A链免疫毒素的摄取抑制约一半，对去糖基化蓖麻毒素A链免疫毒素的摄取影响很小。肝细胞似乎不太可能识别免疫毒素的抗体部分，因为单独的抗体或抗体-牛血清白蛋白偶联物在培养物中没有被大量摄取。可能是A链与抗体的连接暴露了A链上在体外和体内都能被肝细胞识别的位点。