Monitoring of cyclosporin A levels with radioimmunoassay in renal transplant recipients: Comparison of monospecific and nonspecific assays

M. K. Lai*, K. Y. Tzen, Y. C. Ou, Chiu-Ching Huang, S. H. Chu, C. K. Chuang, H. W. Chen, C. S. Chen

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

Abstract

Patients receiving cyclosporin A (CsA) therapy should be monitored carefully in order to avoid side effects and maintained immunosuppression. Radioimmunoassay is one of the most commonly used methods of monitoring CsA levels. The decision to use whole blood vs plasma or monospecific vs nonspecific monoclonal antibodies for the measurement of CsA levels has been a controversial issue. In this study, CsA levels in the whole blood and plasma were measured simultaneously with INCSTAR specific monoclonal antibodies in 20 renal transplant recipients (group A). There was a significant correlation between the CsA levels in the whole blood and plasma (R2 = 0.7379, p < 0.00001). However, at the therapeutic limit, the correlation was not good. The whole blood/plasma CsA concentration ratios were not correlated with the hematocrits of the patients. In another group of 20 renal transplant recipients (group B), CsA levels in whole blood and plasma were measured simultaneously with INCSTAR nonspecific monoclonal antibodies. There was a significant correlation between the CsA levels in whole blood and plasma (R2 = 0.6714, p < 0.00001). The whole blood/plasma ratios were significantly correlated with the hematocrits (R2 = 0.5457, p = 0.0002). The later finding could be due to the extensive cross-reactivity of nonspecific monoclonal antibodies with CsA metabolites, which are almost exclusively bound to the erythrocytes. The hematocrits in renal transplant recipients usually show significant change over a period of time. The plasma levels may be more stable in such cases. However, measurement of whole blood levels also has several advantages, mainly from a technical aspect. Until a better assay technique is available, serial follow-up of the CsA level with clinical correlation and strict quality control in the laboratory seem to be more important issues than the controversy over whether to use whole blood vs plasma or monospecific vs nonspecific assays for CsA monitoring.

Original languageEnglish
Pages (from-to)948-952
Number of pages5
JournalJournal of the Formosan Medical Association
Volume92
Issue number11
StatePublished - 1993
Externally publishedYes

Keywords

  • cyclosporin A
  • radioimmunoassay
  • renal transplantation

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