Development of an Abbott ARCHITECT cyclosporine immunoassay without metabolite cross-reactivity.
OBJECTIVE
We investigated the mechanism by which the ARCHITECT cyclosporine (CsA) chemiluminescent microparticle immunoassay (CMIA) eliminates cross-reactivity to CsA metabolites AM1 and AM9, despite its use of a monoclonal antibody which shows cross-reactivity in fluorescence polarization immunoassays.


METHODS
The CMIA was accomplished by incubating an extracted blood sample with magnetic microparticles coated with a very low amount of anti-CsA antibody. After a wash step the microparticles were incubated with a chemiluminescent CsA tracer, followed by a second wash step and measurement of chemiluminescence. The reagent concentrations of salt and detergent were optimized to maximize CsA binding and minimize metabolite interference.


RESULTS
Elimination of CsA metabolite cross-reactivity was shown using purified metabolites and blood samples containing native CsA metabolites. The CMIA demonstrated precision and sensitivity acceptable for use in a clinical setting.


CONCLUSIONS
We conclude that it is possible to eliminate CsA metabolite immuno-cross-reactivity by careful assay design.
Brate
Elaine M
EM
Abbott Diagnostics, Abbott Park, IL 60064, USA.
Finley
David M
DM
Grote
Jonathan
J
Holets-McCormack
Shelley
S
Ozaeta
Pan F
PF
Pacenti
David
D
Peart
Joan E
JE
Piktel
Ryan E
RE
Ramsay
Carol S
CS
Rupprecht
Kevin R
KR
Saldana
Sylvia C
SC
Spring
Thomas G
TG
Tetin
Sergey Y
SY
Trudeau
Beth C
BC
Wang
Phil
P
Xie
Helen
H
D000911:Antibodies, Monoclonal; D003429:Cross Reactions; D016572:Cyclosporine / Q000097:blood* / Q000378:metabolism; D006801:Humans; D007118:Immunoassay / Q000379:methods* / Q000592:standards; D008163:Luminescent Measurements; D012680:Sensitivity and Specificity
D000911:Antibodies, Monoclonal; D016572:Cyclosporine