Use of a cloud-based search engine of a centralized donor database to identify historical antigen-negative units in hospital inventories.

BACKGROUND: The provision of units with antigen-negative attributes is required for alloimmunized transfusion recipients and to avoid alloimmunization among patients on chronic transfusion support. Recent evidence confirms that the demand for antigen-typed units is increasing. STUDY DESIGN AND METHODS: A cloud-based search engine was designed by the blood center to find antigen-negative units. The service provided access to historical antigen information for units in hospital inventories. The hospital transfusion service was required to confirm the antigen phenotype. The results of 16 hospitals' use over 5 years were analyzed to determine trends and value of the service. The time commitment of the cloud-based query was compared to the hospital performing manual phenotyping with an outcome of at least one unit found with the desired antigen-negative attribute(s). RESULTS: Hospitals were located between 4 miles and 200 miles away from the blood center. A total of 6,081 queries were submitted over the 5 years, with an overall 50% success rate of finding at least one unit. Single antigen queries accounted for 67% of total searches, with two antigen queries and three or more antigen queries accounting for 24% and 9% of the units found, respectively. The cloud-based antigen query was most efficient for combined antigen frequencies <0.5 for two or more antigen-negative attributes. CONCLUSION: A cloud-based search engine provides hospitals with access to historical antigen information housed at the blood center. Future refinements may consider regulatory submission of a process to provide confirmed historical information through this cloud-based program.

Practical approaches and costs for provisioning safe transfusions during anti-CD38 therapy.

BACKGROUND: Anti-CD38 therapy causes interference with both the direct and the indirect antiglobulin tests. We describe the experience from an Immunohematology Reference Laboratory and model cost options for providing safe transfusions. STUDY DESIGN AND METHODS: Phenotyping, genotyping, and antibody identification orders were retrospectively reviewed in the setting of anti-CD38 therapy. The data were used to model the added cost of transfusion support. Four approaches were evaluated: 1) thiol-treated reagent red blood cells (RRCs) in antibody investigations with K- red blood cell (RBC) transfusions, 2) patient phenotyping or 3) genotyping with antigen-matched RBC transfusions, and 4) a combination of interval thiol-treated RRC antibody investigations with genotype antigen-matched RBC transfusions. RESULTS: Sixty-two patients were identified as receiving anti-CD38 therapy. Thiol-treated RRC antibody investigations (28/62 patients) were favored over genotyping (23/62) and combination testing (11/62). Patient phenotyping failed to detect useful antigen information on eight patients: seven Fyb silencing mutations and one partial e. A thiol-treated RRC antibody investigation was the least expensive testing method for the first transfusion, but four- and five-antigen-matched RBC transfusions were equal in cost within five and 21 transfusion events, respectively. CONCLUSION: Genotyping provided a more accurate antigen status than phenotyping patient RBCs. Patients requiring long-term transfusion support benefit from antigen matching when matching less than four antigens. Ultimately, the decision to genotype or use thiol-treated RRC antibody investigations will vary for each hospital blood bank.

Mass-scale donor red cell genotyping using real-time array technology.

Blood centers are in the unique position to evaluate large numbers of blood donations for antigen-negative blood types. The limitations with the use of hemagglutination, however, can be circumvented with red cell genotyping. The reagents used for genotyping are synthesized and can be designed for any of the known blood group antigen single nucleotide polymorphisms that are associated with blood group antigen expression. There is interest in the application of mass-scale red cell genotyping of blood donors to find rare phenotypes and rare combinations of antigens. When performed on donors who are predicted to donate again after testing, integrating the genotype information with existing donor data and demographics provides the blood center with real-time information to identify the common clinically relevant blood group antigens demanded by hospital transfusion services. This review outlines a red cell genotype methodology using TaqMan chemistry and existing algorithms and data handling to gain the full value of mass-scale red cell genotyping of blood donors.

Clinical and reference lab characteristics of patients with suspected direct antiglobulin test (DAT)-negative immune hemolytic anemia.

Clinical evidence of warm autoimmune hemolytic anemia is present in 1 percent to 10 percent of patients whose direct antiglobulin test (DAT) is negative. The clinical underpinnings associated with DAT-negative immune hemolysis are poorly understood, and the current study aimed to further define the clinical characteristics associated with this form of anemia. A 19-question survey, requesting clinical information about each patient, was retrospectively mailed to all referring labs that had sent patient samples for an enhanced DAT evaluation from January 2011 through June 2013. An enhanced DAT evaluation involved a standard DAT and DATs performed using gel, polyethylene glycol, and 4°C low-ionic strength saline wash. We obtained detailed clinical information from 57 patients with an enhanced DAT investigation. Eighteen of these 57 patients (31.6%) were found to have a positive DAT, 11 (19.3%) of which were found to have a positive enhanced DAT (2 were positive by enhanced methods methods and negative by standard methods). The reported mean nadir hemoglobin for all 57 patients was 7.8% g/dL (range 3.2-12.7), and lactate dehydrogenase was 827.8 U/L (range 136-6917). Thirty-seven (18.1%) presented with a haptoglobin <10 mg/dL, and 21 (48.8%) reported spherocytes on peripheral smear. About half of the respondents reported using steroids as treatment for the anemia, and 4 of the 18 DAT-positive respondents (23.5%) changed their treatment plan because of the reference laboratory results. One patient died as a result of the reported hemolytic anemia (2.0%). We conclude that immune hemolysis detected by enhanced DAT methods is relatively common, and enhanced DAT methods are valuable tools in the diagnosis and management of patients with DAT-negative hemolytic anemia.