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Patient Blood Management

(P-PB-2) A Case Of Anti-Tca Alloantibodies: A Success Story In Bloodless Medicine

Sunday, October 20, 2024
12:00 PM - 1:00 PM  
Background/Case Studies: Anti-Tca antibody is a red cell alloantibody first reported in 1975 & 1979 on two black women (GT and DLC, who lend their last initials to the designation Tc). The IgG antibodies characterized a high-frequency antigen thought to be related to the Cromer group antigen. Prior reports suggest that anti-Tca can cause clinically significant hemolysis.

Study

Design/Methods: The patient sample was screened for antibodies according to our institutional procedure using Ortho Clinical Diagnostics Surgiscreen reagent red cells and ID-MTS Gel Cards on the Ortho Vision Swift Analyzer platform. Ultimate antibody identification and monocyte monolayer assay were performed at the American Red Cross Immunohematology Reference Laboratory in Philadelphia, PA.

Results/Findings:

A 73-year-old black woman with atrial fibrillation (on warfarin) and chronic kidney disease (CKD) was admitted to our institution for repair of an acute aortic dissection and received two units of crossmatched compatible red cells. Her antibody screen at that time was negative. She was readmitted one month later due to hypotension and anemia requiring blood transfusion. Antibody screen on readmission was positive, and an anti-Tca antibody was identified. MMA results showed 76.5% and 69.0% reactive monocytes versus two random donors with fresh complement, and 71.5% and 70.5% without fresh complement. As crossmatch compatible units could not be found in our inventory, a nationwide search for Tca negative units was triggered but was unsuccessful.

 

The Transfusion Service requested a consultation with Bloodless Medicine. Her anemia was thought to be multifactorial, encompassing her CKD, warfarin use, recent aortic dissection, and nutritional deficiencies in iron and vitamin B12. Blood draws were limited to 2-3 times per week, using pediatric collection vials when possible. Intramuscular cyanocobalamin supplementation was started at 1000 mcg per day, later tapered to 1000 mcg per week. An additional two doses of 200 mg of intravenous iron were administered. No specific indication was found for use of warfarin, which was discontinued and replaced with apixaban 2.5 mg twice per day. Following these interventions, her hemoglobin increased from 5.9 g/dL to 10.0 g/dL over 16 days (see Figure 1). She was discharged in stable condition.

Conclusions: Anti-Tca is a rare alloantibody which can be clinically significant and cause hemolysis. Patient Blood Management is necessary in treating patients with high frequency antigen antibodies, as compatible red cell units may not be available. In these scenarios, bloodless medicine strategies can be used to maintain satisfactory hemoglobin levels.