Red cell antibodies resulting in false-positive complement-dependent cytotoxicity cross-match: A unique case

Area of Science:

• Nephrology
• Immunology
• Transplantation

Background:

• False-positive complement-dependent cytotoxicity cross-match (CDC XM) results can impede kidney donor selection.
• Accurate cross-matching is crucial for successful renal transplantation.

Observation:

• A patient awaiting renal transplant presented with a positive CDC XM despite negative donor-specific antibody (DSA) lysate XM.
• Indirect antiglobulin test (IAT) revealed a positive result, identifying anti-M alloantibody (IgG + IgM).

Findings:

• Treatment with therapeutic plasma exchange, intravenous immunoglobulin, and rituximab reduced CDC XM positivity and anti-M antibody titers.
• The renal transplant was successfully performed following desensitization therapy.

Implications:

• Red cell alloantibodies, such as anti-M, should be considered in the differential diagnosis of positive CDC XM.
• Donor-specific antibody (DSA) lysate XM is valuable for pre-transplant monitoring in complex cases.
• Establishing institutional protocols for managing discordant CDC XM and DSA lysate XM results is essential.