Systematic identification of human anti-mouse antibody interference causing falsely elevated B-type natriuretic...

Area of Science:

• Clinical Chemistry
• Immunology
• Cardiology

Background:

• B-type natriuretic peptide (BNP) is a key biomarker for diagnosing heart failure.
• Immunoassays used for BNP testing are susceptible to interference from heterophilic antibodies.
• Such interference can result in false-positive findings and inappropriate clinical management.

Purpose of the Study:

• To investigate a case of markedly elevated BNP in a patient with an incongruent clinical presentation.
• To identify the cause of unexplained high BNP levels and establish a diagnostic workflow.
• To demonstrate the impact of human anti-mouse antibody (HAMA) interference on immunoassay results.

Main Methods:

• Stepwise investigation including serial dilution, cross-platform comparison, and heterophilic blocking reagent testing.
• Dose-dependent evaluation of purified mouse IgG and specific blocking reagents.
• Confirmation of interference through normalization of BNP levels.

Main Results:

• A 36-year-old female presented with significantly elevated BNP (2735.7 ± 54.3 pg/mL) inconsistent with her clinical status.
• Serial dilution showed non-linear recovery, and an alternative platform yielded normal results.
• Treatment with purified mouse IgG normalized BNP levels, confirming HAMA interference.

Conclusions:

• Heterophilic antibody interference, specifically HAMA, is a potential cause of unexplained elevations in clinical immunoassay results.
• A systematic approach is crucial for identifying and confirming immunoassay interference.
• Accurate diagnosis and avoidance of unnecessary interventions are facilitated by understanding and addressing assay interference.