Montefiore Medical Center Bronxville, New York, United States
Background/Case Studies: The detection of unexpected antibodies is dependent on the titer of the antibody as well as the strength of antigen expression on reagent red cells used for antibody detection testing (ADT). Two-cell ADT sets require less sample and are typically less expensive than their three-cell counterpart. Three-cell ADT sets typically include donors homozygous for a greater number of antigens compared to the two-cell ADT sets. This case report describes a delayed hemolytic transfusion reaction (DHTR) in a patient with sickle cell disease (SCD) due to an antibody specificity not identified on the two-cell ADT and details the subsequent investigation of weak antibody reactivity on multiple automated instruments using both two-cell and three-cell ADT sets.
Study
Design/Methods: 21 yo male patient with SCD and a history of anti-Jkb experienced a DHTR following transfusion of XM compatible RBCs. ADT was performed at two hospitals in our system on two different solid phase red cell adherence (SPRCA) instruments.
Results/Findings: Day 1 at hospital 1: Patient specimen was positive (anti-Jkb identified) on the Echo with a 3-cell ADT set via SPRCA but was negative in tube-PEG. Day 6 & 10 at hospital 2: Patient specimen was negative with a 2-cell ADT set via SPRCA on the NEO. Based on our hospital systems’ policy, they were transfused RBC units confirmed negative for C, E, K, and Jkb antigens. Eight days following an exchange transfusion, clinical and laboratory findings were highly suggestive of a DHTR. The patient’s samples were sent to a reference laboratory, where an anti-s was identified. Day 11 at hospital 2: Patient specimen was positive with a 3-cell ADT set via SPRCA on the Echo. Based on a review of the QC, maintenance records, and an inspection by manufacturer engineer, the instrument was ruled out as the cause of unexpected negative results and the 2-cell screen was identified as likely cause for not detecting the weakly reactive anti-s. Conclusions: Facilities should carefully consider the risks and benefits of using a 2-cell vs 3-cell ADT set – a decision that may have particularly important implications for detection of weak antibodies
Importance of research: The balance of analytic sensitivity and specificity in antibody detection techniques is a longstanding debate in Transfusion Medicine. Reagent cost, and financial impact thereof, adds an additional layer to decision making. Evaluation of reagents based on the hospital’s patient population and consideration of antigen dose on ADT sets, is key to that decision.
