Törnevik Y, Jacobsson B, Britton S, Eriksson S
Department of Biochemistry I, Karolinska Institute, Stockholm, Sweden.
AIDS Res Hum Retroviruses. 1991 Sep;7(9):751-9. doi: 10.1089/aid.1991.7.751.
Azidothymidine (AZT) inhibits the replication of human immunodeficiency virus and it is the only drug so far licensed for treatment of acquired immunodeficiency syndrome (AIDS). A prerequisite for its antiviral activity is phosphorylation by cellular nucleoside kinases to the mono-, di-, and triphosphate levels. This study determined the capacity of isolated peripheral blood mononuclear cells (PBMC), resting or mitogen stimulated, from 36 different people of whom 5 were HIV+, to phosphorylate and accumulate intracellular AZT nucleotides. We found a large variation in the amount of products formed between PBMC treated at different times from the same individual as well as between the PBMC from different individuals. Resting PBMC showed the largest interindividual variation and their levels of AZT nucleotides were about 60-150-fold lower than in activated PBMC. The intracellular half lives of azidothymidine mono-, di-, and triphosphates, constituting, on the average, 96-99.2, 0.7-1.8, and 0.4-2.7% of total nucleotides at 0.08-1.6 microM AZT, respectively, were also determined. In mitogen-stimulated PBMC it was approximately 2.5 +/- 0.6 h for all the azidothymidine metabolites. The half-life for intracellular azidothymidine monophosphate in resting PBMC from two individuals was determined to 1.5 +/- 0.2 h. There appeared to be no significant difference in the AZT metabolism in PBMC from HIV-positive or-negative persons. A relative decrease in the intracellular formation of AZTDP and AZTTP from AZTMP was observed at concentrations of AZTMP above 1 microM. This fact may explain why lowering the doses of AZT still gives therapeutically efficient levels of the active metabolite AZTTP.
叠氮胸苷（AZT）可抑制人类免疫缺陷病毒的复制，是目前唯一被批准用于治疗获得性免疫缺陷综合征（艾滋病）的药物。其抗病毒活性的一个先决条件是被细胞核苷激酶磷酸化为单磷酸、二磷酸和三磷酸水平。本研究测定了来自36个不同个体（其中5人为HIV阳性）的分离外周血单个核细胞（PBMC），无论是静息状态还是经丝裂原刺激后，磷酸化并在细胞内积累AZT核苷酸的能力。我们发现，同一人在不同时间处理的PBMC之间以及不同个体的PBMC之间，形成的产物量存在很大差异。静息PBMC表现出最大的个体间差异，其AZT核苷酸水平比活化PBMC低约60 - 150倍。还测定了叠氮胸苷单磷酸、二磷酸和三磷酸在细胞内的半衰期，在0.08 - 1.6 microM AZT时，它们分别平均占总核苷酸的96 - 99.2%、0.7 - 1.8%和0.4 - 2.7%。在丝裂原刺激的PBMC中，所有叠氮胸苷代谢产物的半衰期约为2.5±0.6小时。测定了两名个体静息PBMC中细胞内叠氮胸苷单磷酸的半衰期为1.5±0.2小时。HIV阳性或阴性个体的PBMC中AZT代谢似乎没有显著差异。在AZTMP浓度高于1 microM时，观察到从AZTMP到AZTDP和AZTTP的细胞内形成相对减少。这一事实可能解释了为什么降低AZT剂量仍能产生治疗有效的活性代谢产物AZTTP水平。
