Identifying D-positive donors using a second automated testing platform

Area of Science:

• Transfusion Medicine
• Immunohaematology
• Blood Donor Screening

Background:

• Variability in D antigen expression necessitates reliable methods for classifying blood donors with variant RHD alleles.
• Current automated testing may be insufficient for accurate D antigen typing, potentially leading to alloimmunization risks.

Purpose of the Study:

• To evaluate the efficacy of the Immucor Gamma Galileo automated platform in confirming D- results from the Beckman Coulter PK7300 system.
• To estimate the number of alloimmunization cases preventable in women under 50 by implementing dual automated testing.

Main Methods:

• Comparison of D antigen testing results between PK7300 and Galileo automated platforms for first-time blood donors.
• Discordant samples were further analyzed using serologic tube methods, RHD genotyping (BLOODchip), and sequencing.
• Estimation of alloimmunization prevention based on transfusion data and known alloimmunization rates.

Main Results:

• Of 15,441 first-time donors with concordant D- results, five showed D+ on Galileo. One was a false positive; four had positive serologic tests and were C+.
• Further RHD genotyping identified weak D types 67, 9, and two novel variants among the four discordant donors.
• The addition of Galileo testing was estimated to prevent approximately one case of alloimmunization every 5-6 years in women under 50.

Conclusions:

• Adding a second automated serologic testing platform (Galileo) shows a very low yield in preventing alloimmunization in the target population.
• Current D antigen testing strategies appear adequate for most blood donors, with limited benefit from an additional automated platform for this specific outcome.