False-positive immunogenicity responses are caused by CD20+ B cell membrane fragments in an anti-ofatumumab antibody bridging assay.

Chen K, Page JG, Schwartz AM, Lee TN, Dewall SL, Sikkema DJ, Wang C.
Journal   J Immunol Methods
Analytes Measured  
Matrix Tested   Serum
Year   2013
Page Numbers  
Application   Immunogenicity
An electrochemiluminescent (ECL) bridging assay to detect anti-ofatumumab antibodies (ADA) in human serum samples was developed and validated. Using this assay format, clinical samples were first screened to identify potential ADA positive samples, which were then further tested by adding excess drug, confirming the positive signals as drug specific. However, when the method was implemented into clinical studies for ADA testing, a high positive rate was observed in the pre-dose samples collected from patients with chronic lymphocytic leukemia (CLL). Since the positive signals were not associated with ofatumumab (Ofa) treatment, and diminished after treatment, it was suspected that matrix interference might be responsible, resulting in false-positive responses. We performed a series of experimental investigations to identify, characterize, minimize or eliminate the possible false-positive responses. One possible source was identified to be CD20 (the target of Ofa) present on cell membrane fragments (CMFs). The false-positive responses caused by CD20+ CMFs could be reduced by solid-phase immunodepletion, ultracentrifugation, or inhibited by adding another anti-CD20 antibody (rituximab). As a consequence, the ADA method was modified to minimize the matrix interference caused by CD20+ CMFs and, then, validated for sample testing.

View Publications

Related Products

Rat BNP Kit
BNP | Rat
MSD GOLD 96-well Streptavidin SECTOR Plate Pack

Browse Our Products

By Analytes
By Applications
Customer Service/Orders

Scientific/Technical Support

Instrument Support

Company Headquarters