An ELISA for quantification of murine IgG in rat plasma: Application to the pharmacokinetic characterization of AP-3, a murine anti-glycoprotein IIIa monoclonal antibody, in the rat

An enzyme-linked immunosorbent assay (ELISA) has been developed to determine concentrations of murine IgG in rat plasma. Specifically, the assay was developed to measure a murine anti-glycoprotein IIIa antibody (AP-3) in rat plasma to facilitate future investigations of AP-3 pharmacokinetics and pharmacodynamics in the rat. The working range of the assay is 15-100 ng ml^{- 1}, corresponding to a limit of quantification of 1.5 μg ml^-1 in rat plasma. The assay was validated with respect to accuracy, precision, and cross-reactivity with both pooled rat and mouse IgG. Intra-assay recoveries of AP-3 in rat plasma ranged from 93 to 103% with CV% values ranging from 5.2 to 8.5%. Inter-assay recoveries of the plasma AP-3 samples ranged from 107 to 119% with CV% values ranging from 17.7 to 25.1%. The assay has no appreciable cross reactivity with pooled rat IgG and full cross reactivity with pooled mouse IgG, making this an ideal assay to determine plasma pharmacokinetics of mouse antibodies in the rat. The assay was used to determine the pharmacokinetics of AP-3 in a Sprague-Dawley rat.