Risk Assessment

A prospective wet crossmatch is often not possible in the time available prior to a cardiothoracic transplant. In the UK, instead of a wet crossmatch, a virtual crossmatch risk stratification based on the British Transplant Society (BTS) guidelines is carried out based on Luminex defined Donor Specific Antibodies (DSA) as follows:

• No DSA = Level I Standard Risk
• DSA < 2000 MFI = Level II Low Risk
• DSA > 2000, < 5000 = Level III Intermediate Risk. Low risk of hyperacute rejection but significant risk of early rejection and antibody mediated graft damage. Immediate pre-transplant antibody reduction may be considered when feasible
• DSA > 5000, = Level IV High Risk

A CDC test result if available would also be used as part of the risk stratification. Luminex Pos. CDC Neg. with cumulative DSA less than 10000 would not be considered a contraindication in most transplant units provided no individual DSA was greater than 5000 MFI.

A retrospective Flow crossmatch (and potentially also a CDC crossmatch) is carried out post-transplant and a Luminex SAB test on the day of transplant sample to help with post-transplant risk stratification.

Cumulative DSA MFI more than 5000

A cumulative DSA MFI of more than 5000 but less than 10000 would not be considered a contraindication to transplantation in most transplant units provided no individual DSA was greater than 5000. MFI Depending on the clinical urgency and logistical practicality, a prospective wet crossmatch may be undertaken to aid risk assessment if possible. A prospective Luminex SAB test may be required depending on the date bled of the last test (greater than 3 months since last sample) and any sensitising events since that sample.