2020 Revised grading criteria for human leukocyte antigen crossmatching test
| Category | Crossmatching methods | Grades for negative response | Grades for positive response |
|---|---|---|---|
| CDC | |||
| 1 | CDC consensus positive (80%) | Unacceptable | Acceptable |
| 2 | CDC consensus negative (90%) and FCM negative consensus | Acceptable | Unacceptable |
| 3 | CDC consensus negative (90%) and FCM positive (≥10%) | Acceptable | Code 505 |
| 4 | No consensus | Code 505 | Code 505 |
| FCM | |||
| A | FCM consensus positive (80%) | Unacceptable | Acceptable |
| B | FCM consensus negative (90%) and DSA negative | Acceptable | Unacceptable |
| C | FCM consensus negative (90%) and DSA positive (>50%) | Acceptable | Code 505 |
| D | No consensus | Code 505 | Code 505 |
Abbreviations: CDC, complement dependent cytotoxicity; FCM, flow cytometry; Code 505, not graded; DSA, donor-specific antibody.