A hemolytic anti‐LKE associated with a rare LKE‐negative, “weak P” red blood cell phenotype: alloanti‐LKE and alloanti‐P recognize galactosylgloboside and monosialogalactosylgloboside (LKE) antigens

Background“Weak P” is a rare red blood cell (RBC) phenotype, characterized by a global decrease in Pk and P antigens. We now describe a second weak P individual who also typed LKE‐negative (LKE‐N) and possessed a clinically significant anti‐LKE.Study Design and MethodsPatient RBCs and plasma were examined by standard serology and flow cytometry. Glycosphingolipids (GSLs) from patient, Pk, and LKE‐strong (LKE‐S) RBCs were isolated and analyzed by high‐performance thin‐layer chromatography (HPTLC). To confirm antibody specificity, patient serum and 30 human polyclonal controls, including alloanti‐P and anti‐PP1Pk, were tested against a panel of GSLs by HPTLC immunostaining.ResultsThe patient typed P1+, P+, and LKE‐N and possessed a “P‐like” panagglutinin. In a two‐stage indirect antiglobulin test, the patient's plasma caused hemolysis of LKE‐S cells but not p, Pk, or LKE‐N cells. Clinically, transfusion of P+ RBCs compatible by a prewarmed technique had shortened RBC survival with laboratory evidence of hemolysis. Analysis of the patient's isolated RBC GSLs showed a 30% relative decrease in Gb3 (Pk) and Gb4 (P) and a 90% decrease in monosialogalactosylgloboside (MSGG, LKE), accompanied by increased lactosylceramide (CDH), paragloboside, and GM3. On HPTLC immunostaining, the patient's plasma strongly bound MSSG with weak binding to galactosylgloboside (Gb5). Binding to MSGG, Gb5, and Gb4 was also observed with some examples of alloanti‐P from Pk individuals, but not anti‐PP1Pk, autoanti‐P, or normal controls.ConclusionsWe describe the first example of a clinically significant anti‐LKE in the setting of a rare weak P background. Human alloanti‐LKE and some alloanti‐P recognized Gb5 and MSGG.