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Flow vs CDC Crossmatch Interpretation — ESENeph MCQ

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HardTransplantationFlow vs CDC Crossmatch InterpretationESENeph

A kidney transplant recipient has a positive flow cytometric crossmatch but negative complement-dependent cytotoxicity (CDC) crossmatch. What does this mean?

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Correct answer: EThe flow cytometric crossmatch is more sensitive than CDC and can detect low-level donor-specific antibodies that are insufficient to fix complement; a positive flow/negative CDC crossmatch indicates lower-level DSA – transplantation may proceed with enhanced monitoring or desensitisation in some protocols

The CDC crossmatch detects complement-fixing antibodies (high-titre, clinically significant DSA that cause hyperacute rejection). The flow cytometric crossmatch is approximately 10-100x more sensitive, detecting lower-level DSA that may not fix complement. A positive flow/negative CDC result indicates low-level DSA. Clinical significance varies: some centres proceed with transplantation using enhanced immunosuppression and close DSA monitoring; others consider desensitisation. The virtual crossmatch (using Luminex single-antigen bead assays to predict compatibility) has largely supplemented physical crossmatching.

Reference: BTS 2018 – Sensitisation; NHSBT – Crossmatch Protocols