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Abstract

Blood Center/Blood Hospital-Based Donor Center

Oral Abstract - Blood Donor Testing

OA2-AM24-SN12 - The Effect of Age and Gender on Anti-A/B IgM Antibody Titers in O Rh(D) Positive Donors

Sunday, October 20, 2024
2:00 PM - 3:00 PM  
Location: 332
CE: Zero
Disclosure(s):
Samantha G. Ngamsuntikul, MD: No financial relationships to disclose
Background/Case Studies: Anti-A and anti-B antibodies pose a risk of acute hemolytic transfusion reactions in recipients with the corresponding antigen. Debate continues on the titer of anti-A and B and which antibody class, IgM or IgG, to test to ensure optimal safety. The US military uses a single titer cutoff of < 1:256 of IgM anti-A and B as safe in non-group O recipients. Our center has been providing low titer O positive whole blood (LTOWB) for pre-hospital use using the cutoff of < 1:256 for over six years. With the rest of the country’s increasing interest in starting their own LTOWB pre-hospital program, our center’s data on the effect of age and gender on isoagglutinin titers may help to create a targeted recruitment program.

Study

Design/Methods: In October 2017, our center started a LTOWB program by screening O Rh(D) positive male fixed-site donors with a history of 2 or more donations for isoagglutinin levels. In September 2022, O Rh(D) positive females with a similar donation history were added to our program if they had never been pregnant or had tested negative for HLA antibodies. Our program defines low titer as < 1:256 IgM Anti-A and Anti-B (IgM anti-A/B) antibodies, in concordance with the military protocol. Plasma from ethylenediaminetetraacetic acid (EDTA) samples was tested using saline (0.9%) diluent. Diluted plasma (50uL) was mixed with 50uL of commercially available A1 and B cells, incubated at room temperature for 5 minutes, centrifuged for 15 seconds at 3600 rpm, and read for agglutination.  Reactivity for either anti-A or anti-B at 1:256 constituted a positive result. Donor age and gender were retrieved from the blood establishment computer system.

Results/Findings:

Since October 2017, a total of 27,400 total titers have been performed in 18,086 unique donors. For donors tested on multiple occasions, a single high titer result constituted a high titer categorization for this data analysis. Table 1 shows the data stratified by gender and age. Using Fisher Exact, the prevalence of high titer IgM anti-A/B antibodies was statistically significantly lower in males compared to females and both genders show a statistically significant decrease in high titer prevalence with age.

Conclusions: In our center’s population, male donors over the age of 30 and female donors (who have never been pregnant or are negative for HLA antibodies) over the age of 50 are the best target populations to screen for LTOWB programs.