Minimal variation in anti-A and -B titers among healthy volunteers over time: implications for the use of out -of- group blood components.

Background: Using potentially out-of-group blood components, like low titer A plasma and O whole blood, in the resuscitation of trauma patients is becoming increasingly popular. However, very little is known whether the donors' anti-A and/or -B titers change over time and whether repeated titer measurements on the same donor are required to ensure that each donation produces a low titer product. Methods: The anti-A and/or -B titers were measured on 56 healthy adult volunteers (47 blood donors; 9 blood center personnel) every three months for 12 consecutive months using an automated solid phase analyzer. The results were expressed as log2 titer steps (e.g., titer 32 = 5 titer steps). Results: Minor variations in the average anti-A and/or -B titers were seen over time; the maximum individual SD in each group was 1.50 (IgG anti-A) or 1.00 (IgM anti-A, IgM and IgG anti-B). When the SDs for the 4 titer measurements from all 56 volunteers were combined as appropriate, the highest overall combined SD was 0.47 titer steps for IgG anti-A. This value corresponds to a 95% confidence interval for intra-individual variation in this antibody's titer over 12 months of 0.96 titer steps. Thus, based on one measurement, an IgG anti-A with a titer step of, for example, 6 would be expected to be in the range of titer step 5 to titer step 7 over the course of one year with 95% probability. Conclusion: The titers of anti-A and/or -B among healthy adults are stable over at least one year. This suggests that repeated titer measurements within a year on the same donor are not necessary if donations are made at >=3 month intervals. Level of evidence: 5 Study type: Diagnostic test (C) 2017 Lippincott Williams & Wilkins, Inc.

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