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.

T he video clip is a demonstration of how hospital transfusion service staff uses an online cloud-based search engine to find blood with desired antigennegative attributes. This blood center-developed tool, termed Antigen Query, provides hospital transfusion services the ability to look up historical antigen-negative data on the blood in their inventory. The functionality largely relies on mass-scale red cell genotyping of blood. 1,2The process begins with entering patient demographics into an online form. Next, staff scans ISBT 128 unit numbers to create an online worksheet that is sent electronically to the blood center. Completing and submitting the prompts takes approximately 5 minutes. The algorithm used by the blood center identifies those units with antigen-negative attributes. An electronic table is then returned to the user that displays the antigen information. The search identifies the units with antigen-negative attributes up to the desired number of units requested. If the search is unsuccessful or only partially successful, another search can be performed using other units or an order can be placed directly with the blood center. Units with antigen-positive attributes are displayed to exclude them from additional antigen-negative searches.

BACKGROUND: The provision of units with antigennegative 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 hospitalsʼ 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.From the

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. Immunohematology 2015;31:69-74.

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 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 (88.1%) 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. Immunohematology 2015;31:108–115.