Solutions to Avoid False Positives for Rituximab in Pre-Transplant Crossmatches

Area of Science:

• Immunology
• Transplantation Immunology

Background:

• Rituximab, an anti-CD20 immunotherapy, is widely used for B cell depletion.
• Its presence in sera can interfere with pre-transplant crossmatch assays, leading to false positive results in flow cytometry (FCXM) and complement-dependent cytotoxicity (CDCXM).
• Previous methods like pronase treatment to mitigate these interferences have shown limitations, including alteration of Human Leukocyte Antigen (HLA) molecules.

Observation:

• This study investigated the efficacy of a novel anti-rituximab monoclonal antibody (10C5) to prevent rituximab-induced false positives.
• Serum samples from ten patients treated with rituximab were utilized.
• Cells were incubated with sera pre-treated or not pre-treated with the 10C5 antibody.

Findings:

• Pre-incubation with the anti-rituximab antibody (10C5) at a 1:5 proportion successfully excluded false positives in both FCXM and CDCXM.
• This method prevented misinterpretation of crossmatch results, especially in patients with specific donor antibodies (DSA).
• Crucially, the 10C5 antibody did not affect HLA molecules.

Implications:

• The anti-rituximab antibody (10C5) offers a reliable method to ensure accurate pre-transplant crossmatch results in patients undergoing rituximab therapy.
• This approach enhances the safety and efficacy of organ transplantation by preventing erroneous immunological assessments.
• It provides a valuable alternative to existing methods, preserving HLA integrity for more precise donor-recipient matching.