Murthy J N, Yatscoff R W, Soldin S J
Department of Laboratory Medicine, Children's National Medical Center, Washington, DC, USA.
Clin Biochem. 1998 Apr;31(3):159-63. doi: 10.1016/s0009-9120(98)00007-1.
There is a controversy regarding the role of cyclosporine (CsA) metabolites in both immunosuppression and toxicity, and measurement of the parent drug is commonly recommended. High performance liquid chromatography (HPLC) is the method commonly used for specific measurement of the parent drug, but is very time consuming. Antibody techniques are available but vary in specificity. Mixed lymphocyte culture assay (MLC) is a functional bioassay for the measurement of CsA which measures both parent drug and active metabolites. Because it is time consuming and labor intensive, it is not practical to use the MLC to monitor patient's CsA levels. The objective of this study is to evaluate the degree of cross-reactivity or interference among two different CsA immunoassays [(Immunoassay: CYCLO-Trac-RIA, Monoclonal-TDX; and two radioreceptor assays (RRA) (52 kDa immunophilin and cyclophilin)] with seven cyclosporine metabolites (AM19, AM1c9, AM4n9, AM1, AM9, AM1c, AM4n). The results are compared with a previously published MLC assay for the same metabolites.
500 ng/mL of each of the CsA metabolites was assayed in spiked blood samples with both RRA using 52 kDa immunophilin and commercial cyclophilin and two commonly used commercial immunoassay procedures. The results were compared to those obtained with the previously published MLC assay.
The CYCLO-Trac-radioimmunoassay showed minimal cross-reactivity with all of the seven CsA metabolites tested and is more specific to parent CsA than the current Abbott monoclonal procedure for the measurement of CsA. However the cross-reactivity of the seven metabolites using the Abbott monoclonal assay matched closely with their pharmacological potency as measured in the MLC assay. The RRAs showed greater cross-reactivity for most of the CsA metabolites tested than that found in the immunoassay procedures.
环孢素（CsA）代谢产物在免疫抑制和毒性方面的作用存在争议，通常建议测定母体药物。高效液相色谱法（HPLC）是常用于特异性测定母体药物的方法，但耗时很长。有抗体技术可用，但特异性各不相同。混合淋巴细胞培养试验（MLC）是一种用于测定CsA的功能性生物测定法，可同时测定母体药物和活性代谢产物。由于耗时且劳动强度大，使用MLC监测患者的CsA水平并不实际。本研究的目的是评估两种不同的CsA免疫测定法[免疫测定法：CYCLO-Trac-RIA、单克隆-TDX；以及两种放射受体测定法（RRA）（52 kDa亲免素和亲环蛋白）]与七种环孢素代谢产物（AM19、AM1c9、AM4n9、AM1、AM9、AM1c、AM4n）之间的交叉反应程度或干扰情况。将结果与先前发表的针对相同代谢产物的MLC测定法进行比较。
用含有52 kDa亲免素和商业亲环蛋白的两种RRA以及两种常用的商业免疫测定程序，对加标的血样中每种500 ng/mL的CsA代谢产物进行测定。将结果与先前发表的MLC测定法所获结果进行比较。
CYCLO-Trac放射免疫测定法与所测试的所有七种CsA代谢产物的交叉反应极小，并且与当前用于测定CsA的雅培单克隆程序相比，对母体CsA更具特异性。然而，使用雅培单克隆测定法时，七种代谢产物的交叉反应与其在MLC测定法中测得的药理效力密切匹配。对于所测试的大多数CsA代谢产物，RRA显示出比免疫测定程序更大的交叉反应。
