Noninterchangeability of specific radioimmunoassay and monoclonal antibody fluorescent polarization immunoassay in cyclosporine measurements.
This study compares cyclosporine (CsA) concentrations in whole blood from patients receiving bone marrow (n = 10), renal (n = 48), heart (n = 50) or liver (n = 50) transplants, as measured by monoclonal antibody flurorescence polarization immunoassay (FPIA) and specific 125I-radioimmunoassay (RIA). The FPIA overestimated CsA by an average of 25%. Results were higher for all indications: FPIA/RIA ratios were 1.17 for bone marrow, 1.23 for renal and 1.27 for both heart and liver transplants, and these values were significantly different from 1.0. The percentage of overestimation was higher at low CsA concentrations (< or = 100 micrograms/L) than at high CsA concentrations (> or = 400 micrograms/L). In all indications, results by both methods correlated well (r > 0.96) but slopes and intercepts were different from 1.0 and 0.0, respectively, and these parameters varied greatly between the grafted populations. These findings obtained with the two methods could not be attributed to matrix effect because the mean FPIA/RIA ratio for spiked control samples was 1.0. The discrepancy between the FPIA and RIA could be explained by the lower specificity of the monoclonal antibody contained in the FPIA kit. These results suggest that FPIA is not as accurate as RIA and that the two methods are not interchangeable in CsA level measurement.
Laboratoire de Pharmacologie Clinique, Faculté de Médecine, Rennes, France.
D
D
Pape
L
L
Vernillet
E
E
Bellissant
D
D
Bentue-Ferrer
H
H
Allain
D000911:Antibodies, Monoclonal; D016026:Bone Marrow Transplantation; D016572:Cyclosporine / Q000097:blood* / Q000627:therapeutic use; D005454:Fluorescence Polarization; D006084:Graft Rejection / Q000517:prevention & control; D016027:Heart Transplantation; D006801:Humans; D007166:Immunosuppressive Agents / Q000097:blood* / Q000627:therapeutic use; D016030:Kidney Transplantation; D016031:Liver Transplantation; D011786:Quality Control; D011863:Radioimmunoassay; D012044:Regression Analysis; D015203:Reproducibility of Results
D000911:Antibodies, Monoclonal; D007166:Immunosuppressive Agents; D016572:Cyclosporine