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 P(k) 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 METHODS: Patient RBCs and plasma were examined by standard serology and flow cytometry. Glycosphingolipids (GSLs) from patient, P(k) , 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-PP1 P(k) , were tested against a panel of GSLs by HPTLC immunostaining. RESULTS: The 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, P(k) , 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 (P(k) ) 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 P(k) individuals, but not anti-PP1 P(k) , autoanti-P, or normal controls. CONCLUSIONS: We 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.

Rh discrepancies caused by variable reactivity of partial and weak D types with different serologic techniques.

BACKGROUND: RhD discrepancies between current and historical results are problematic to resolve. The investigation of 10 discrepancies is reported here. STUDY DESIGN: Samples identified were those that reacted by automated gel technology and were negative with an FDA-approved reagent. Reactivity with a commercially available panel of monoclonal anti-D was performed. Genomic DNA was evaluated for RHD alleles with multiplex RHD exon polymerase chain reaction (PCR), weak D PCR-restriction fragment length polymorphism, and RHD exon 5 and 7 sequence analyses. RESULTS: The monoclonal anti-D panel identified two samples as DVa, yet possessed the DAR allele. Two weak D Type 1 samples had a similar monoclonal anti-D profile, but only one reacted directly with one of two FDA-approved anti-D. Only two of four weak D Type 2 samples reacted directly with one FDA-approved anti-D, and their D epitope profile differed. CONCLUSIONS: The monoclonal anti-D reagents did not distinguish between partial and weak D Types 1 and 2. Weak D Types 1 and 2 do not show consistent reactivity with FDA-approved reagents and technology. To limit anti-D alloimmunization, it is recommended that samples yielding an immediate-spin tube test cutoff score of not more than 5 (i.e., < or =1+ agglutination) or a score of not more than 8 (i.e., < or =2+ hemagglutination) by gel technology be considered D- for transfusion and Rh immune globulin prophylaxis. That tube test anti-D reagents react poorly with some Weak D Types 1 and 2 red cells is problematic, inasmuch as they should be considered D+ for transfusion and prenatal care. Molecular tests that distinguish common partial and Weak D types provide the solution to resolving D antigen discrepancies.

Case report and literature review: transient Inab phenotype and an agglutinating anti-IFC in a patient with a gastrointestinal problem.

BACKGROUND: The Inab phenotype is a rare deficiency of all Cromer antigens. These antigens are carried on the decay-accelerating factor (DAF, CD55) molecule that is attached to the red blood cell (RBC) membrane by a glycosylphosphatidylinositol (GPI) anchor. Although typically inherited, an acquired and transient form of the Inab phenotype also exists. A patient with the triad of transient Inab phenotype, a direct-agglutinating anti-IFC, and gastrointestinal (GI) abnormalities is reported. CASE REPORT: An 18-month-old boy with gastroesophageal reflux disease requiring a feeding tube, milk and soy intolerance, and severe growth retardation, as well as vision and hearing deficits from cytomegalovirus infection, was identified when pretransfusion testing revealed a potent panagglutinin (titer > 2000 at 4 degrees C). This antibody did not react with Dr(a-) and IFC RBCs, and the autocontrol was negative. The patient's RBCs lacked CD55 by flow cytometric techniques but had normal levels of CD59 and antigens such as Yt(a) and Emm, carried on GPI-linked proteins, thus excluding paroxysmal nocturnal hemoglobinuria. Several months after initial detection, the anti-IFC was virtually undetectable and his cells reacted weakly with anti-IFC, anti-Dr(a), and anti-CD55. RBCs from the propositus' parents and brother demonstrated normal CD55 and CD59 expression. CONCLUSION: This is the first example of a direct-agglutinating anti-IFC. The cause of the transient depression in CD55 protein (and thus Cromer system antigens) and appearance of anti-IFC remains unknown, as does the relationship between the patient's GI system abnormalities and these serologic findings.

Persistence of cefotetan on red blood cells.

BACKGROUND: Cefotetan can cause severe immune hemolytic anemia that may persist long after the drug is discontinued. To study the binding of cefotetan to RBCs, patients who received cefotetan were followed and tested for the presence of antibody to cefotetan. STUDY DESIGN AND METHODS: Patients receiving cefotetan were identified from pharmacy and nursing records. Blood samples obtained for routine hematology tests were analyzed. Cefotetan binding to patients' RBCs was tested using a previously characterized high-titer anticefotetan serum by gel technique. To determine the minimum amount of drug necessary for binding to occur, RBCs were incubated with serial dilutions of cefotetan at pH 7.4. RESULTS: Sixty patients receiving 1 to 25 g i.v. (median, 2 g) of cefotetan were followed for 1 to 123 days (median, 18 days). All were initially positive, for cefotetan on RBCs. Positivity persisted for up to 98 days after the last dose of drug. Fifteen patients became negative during follow-up. The first negative sample occurred at Day 30 to 123. Using the midpoint between the last positive and first negative to estimate of the duration of positivity, we estimate that cefotetan remains RBC-bound for 16.5 to 92 days (median, 67.5 days). During the follow-up period, five patients developed anticefotetan detectable in the serum. Twenty patients receiving other cephalosporin antibiotics showed no specific reactivity of their RBCs with anticefotetan. In vitro studies showed a minimum necessary drug concentration of 1 micromol/L at physiologic pH, which was not significantly altered by RBC pretreatment with ficin, sialydase, or DTT. CONCLUSIONS: Cefotetan is tightly bound to RBCs after intravenous administration and remains detectable for weeks after the last dose. Antibodies to cefotetan may occur in about 8 percent of patients receiving the drug. The minimum necessary concentration for RBC binding is low compared to an estimated plasma concentration of 240 micromol/L from a single i.v. dose of 1 g.