COMPARISON OF CYCLOSPORINE-G (NVA(2)-CYCLOSPORINE) CONCENTRATIONS MEASURED IN WHOLE-BLOOD BY MONOCLONAL FLUORESCENCE POLARIZATION IMMUNOASSAY, MONOCLONAL RADIOIMMUNOASSAY, AND HPLC

Two commercial monoclonal immunoassays for monitoring cyclosporin A we re used to measure whole-blood concentrations of the immunosuppressant cyclosporin G (CsG) in renal transplant patients. We performed a thre e-way comparison of these two immunoassays and HPLC. Although the two immunoassays agreed favorably, both the monoclonal fluorescence polari zation immunoassay and the monoclonal RIA yielded higher CsG results f or patients' specimens than did the liquid-chromatographic assay. The experimental data indicate that the observed differences are most like ly due to the cross-reactivity of CsG metabolites in the immunoassays.