Subjects-Incidence, Species Specificity, and Effects on a Two-SiteAssay for CreatineKinase-MBIsoenzyme

With a two-site CK-MB assay, we screened serum samples from 1008 blood donors for the presence of antibodiesto mouse monoclonalImmunoglobulin.These antibodies were capable of cross-linkingthe labeled antibodywith the solid-phase antibody in the two-site assay, thus generating a falselyhighapparentCK-MB concentration.In 92 (9.12%) of the blood donors tested, apparentCK-MB concentrationsof 10-1000 ug/L decreased to <3 pg/L when re-assayed with non-immunemouse serum (10 mL/L) includedin the assay reagent.We testedthe abilityof non-immunesera fromother animal species to lower the concentrationof apparent CK-MB in 58 of the 92 samples. Bovine and ovine serum were almost as effective as mouse serum; feline, canine, and rabbitserumwere lesseffective.Of the samples tested, 12% (1.1 % of the originalpopulationscreened)showedapparen