(P-TS-104) Three Cases of Neonatal Red Cell Antibody Formation in Patients with Severe Immune Dysregulation at a Single Institution

Patients < 4 months of age do not typically produce antibodies directed towards red blood cell (RBC) antigens. However, sporadic cases of neonatal auto- and alloimmunization have been reported. Here, we describe 3 cases of RBC antibody formation in patients < 4 months of age.

Study

Design/Methods:

Cases are from a single pediatric tertiary care institution. Antibody screens/panels used gel and PEG-IAT methods.

Results/Findings:

Of 1492 patients < 4 months of age receiving RBC transfusions from July 2018 to April 2024, 3 (0.2%) had de novo RBC antibodies.

Case 1 is a 2-month-old who presented with acute liver failure likely due to giant cell hepatitis and autoimmune hemolytic anemia (AIHA). Initial gel screen was positive in all screening cells with a positive autocontrol (AC). Testing at immunohematology reference laboratory (IRL) found a positive DAT (3+ polyspecific, 3+ anti-IgG, 1+ anti-C3) and elution showed a panagglutinin consistent with warm autoantibody. Underlying alloantibodies were excluded using the patient’s alloadsorbed plasma. Maternal antibody screen was negative. AIHA initially treated with steroids post-liver transplant.

Case 2 is a 3-month-old transferred from an outside hospital (OSH) for treatment of infantile autoimmune enterocolitis, hyperinflammatory state due to NLRC4 mutation, and hemophagocytic lymphohistiocytosis (HLH). At OSH the prior month, the patient had negative antibody screens and received several RBC transfusions. Maternal antibody screen was negative. Initial gel screen/panel showed non-specific reactivity.  IRL work-up revealed a positive DAT (2+ polyspecific, 2+ anti-IgG, negative anti-C3) with negative eluate; antibody identification showed an antibody of undetermined specificity. Underlying alloantibodies were excluded by gel and PEG-IAT methods. The patient had no laboratory evidence of hemolysis, received 1 RBC aliquot, and required no further transfusions or antibody screens.

Case 3 is a 3-month-old who transferred from an OSH for familial HLH treatment. At the OSH, patient had a negative antibody screen and received 1 RBC and 1 platelet transfusion. Admission antibody screen was negative and the patient received 1 RBC transfusion. 7 days later, antibody screen was positive with anti-Jka antibody and remained positive with anti-Jka for the next month with no lab evidence of hemolysis. Phenotypically, patient and mother were Jka-negative. Maternal antibody screen was negative. HLH initially treated with emapalumab and steroids. Patient received Jka-negative RBCs for remainder of treatment course including stem cell transplant from mother.

Conclusions:

The multiple etiologies for anemia make hemolysis evaluation challenging in these cases. In disorders with immune dysregulation such as HLH and giant cell hepatitis with AIHA, de novo antibody formation may be seen in neonates, and transfusion services may consider more frequent evaluation for red cell antibodies.