Plasma half-lives and bioavailability of human monoclonal Rh D antibodies BRAD-3 and BRAD-5 following intramuscular injection into Rh D-negative volunteers

Abstract

SUMMARY Two human MoAbs, BRAD-3 (an IgG3 anti-D) and BRAD-5 (an IgG1 anti-D), were produced from Epstein-Barr virus (EBV)-transformed B lymphoblastoid cell lines grown in hollow fibre bioreactors. Six Rh D-negative male volunteers were injected intramuscularly with anti-D; two received BRAD-3 (approx. 1500μg, 2600IU), two were given BRAD-5 (300 μg, 2000 IU), and two had polyclonal anti-D immunoglobulin (500IU, approx. 100μg anti-D). Levels of anti-D in plasma samples taken up to 42 days later were measured by a sensitive AutoAnalyser method. The half life of BRAD-5 (mean 22·2 days) was greater, and that of BRAD-3 (mean 10·2 days) less than that of polyclonal anti-D (mean 15·6 days). The bioavailability (plasma uptake) of the MoAbs (mean 33·9%) was less than that of the polyclonal anti-D (mean 60·3%). BRAD-3 and BRAD-5 may be suitable for use in antenatal and post-natal prophylaxis against Rh D haemolytic disease of the newborn.