Abstract: SA-PO1167
Mythbusters: Is Your ABO Titer Method Safe for Patients?
Session Information
- Transplantation: Clinical - Rejection, Recurrent Disease, Incompatibility
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Transplantation
- 1902 Transplantation: Clinical
Authors
- Jones, Shauna C., Mayo Clinic Hospital, Phoenix, Arizona, United States
- Adamski, Jill, Mayo Clinic, Phoenix, Arizona, United States
- Kinard, Theresa, Mayo Clinic, Phoenix, Arizona, United States
- Finegan, Karen, Mayo Clinic Hospital, Phoenix, Arizona, United States
- Lu, Qun, Mayo Clinic, Phoenix, Arizona, United States
Background
As transplantation of group A2 kidneys to group B patients becomes increasingly common, so does the practice of sending titers to reference labs, some of whom may not be performing their titers in a way that promises optimum patient safety and outcomes. ABO titer cutoff for transplant eligibility differs widely between institutions, largely due to differences in titration methods. Our study sought to refute the notion that a DTT-treated titer read at immediate spin (IS) is an accurate assessment of IgG titer and to suggest widespread adoption of more appropriate, traditional titer testing methods.
Methods
A method comparison study was performed by testing Anti-A titers of 10 group B kidney transplant candidates at immediate spin (IS), traditional tube method (tube AHG), DTT-treated IS (IS DTT), and DTT-treated tube method (AHG DTT). Dilution controls were performed for each patient.
Results
All IS and 9 of 10 AHG titers were reduced by DTT treatment. The amount of reduction varied, as shown in Table 1, suggesting that the proportion of ABO titer which is IgM vs. IgG varies individually. The highest AHG tube titer (256) was reduced down to an IS DTT titer of only 4. In this instance a patient with a high titer Anti-A would have been eligible to receive an A2 transplant at many institutions which use IS DTT titers.
Conclusion
Traditional titer methods which measure IgM and IgG provide a more comprehensive and clinically valuable view than DTT-treated titers. The practice of performing IS DTT-treated titers and reporting as IgG titer is misleading, with possibly harmful implications for patients. Titer performance must be standardized to prioritize patient outcome. Clinicians who refer ABO titers to reference labs should thoroughly assess the method being used to perform these titers and demand a method which ensures patient safety.
Table 1
| Patient | IS Tube | AHG Tube | IS DTT | AHG DTT | Δ IS (# of tubes) | Δ AHG (# of tubes) |
| 1 | 32 | 32 | 4 | 16 | -3 | -1 |
| 2 | 64 | 256 | 4 | 64 | -4 | -4 |
| 3 | 32 | 32 | 8 | 32 | -3 | 0 |
| 4 | 32 | 16 | 2 | 2 | -4 | -3 |
| 5 | 32 | 128 | 2 | 4 | -4 | -5 |
| 6 | 32 | 64 | 8 | 32 | -2 | -1 |
| 7 | 32 | 128 | 2 | 1 | -4 | -7 |
| 8 | 32 | 128 | 1 | 64 | -5 | -1 |
| 9 | 64 | 64 | 4 | 4 | -4 | -4 |
| 10 | 32 | 64 | 8 | 32 | -2 | -1 |