Lot-to-lot variability in HLA antibody screening using a multiplexed bead-based assay
- This work was supported by the National Heart, Lung, and Blood Institute (Transfusion Medicine SCCOR P50HL081027; PT) and Retrovirus Epidemiology Donor Study-II (REDS-II).
Address reprint requests to: Manish J. Gandhi, MD, Division of Transfusion Medicine, Mayo Clinic, 200 1st Street SW, Rochester MN 55905; e-mail: Gandhi.firstname.lastname@example.org, email@example.com.
Identifying antibodies to HLA (anti-HLA) by solid-phase assays is used to screen blood donors to mitigate transfusion-related acute lung injury risk. Various cutoffs for detection assays have been proposed in the literature; however, these do not take into consideration lot-to-lot variability of commercially available assays.
Study Design and Methods
Samples from 93 nontransfused males were tested using five different lots of a multiplex bead-based anti-HLA detection kit. A subset of 17 samples was tested on 5 days using a single lot. An additional 96 samples from donations with varied anti-HLA levels were tested using kits from two different lots. Results were reported as a normalized background (NBG) ratio.
For the 93 nontransfused donors, NBG values generated using the reference lot were significantly higher than those obtained with three of the four comparator lots. However, for the 96 samples with low-, moderate-, and higher-level anti-HLA, Class I (CL-I) values were 1.4 times lower and Class II (CL-II) values were 1.2 times lower using the reference versus comparator lot. For CL-I antibodies the between-lot standard deviation (SD) was 1.36 (95% confidence interval [CI], 1.19-1.60), while the between-day SD was 1.27 (95% CI, 1.08-1.52). Similarly, for CL-II antibodies the between-lot SD was 0.81 (95% CI, 0.70-0.95), while the between-day SD was 0.50 (95% CI, 0.43-0.60).
There is interlot variability in the tested HLA detection assay as well as significant bias between lots. It may be reasonable to develop a new cutoff when a new lot is obtained.