In vivo red cell destruction by anti-Lu6

Blood doping in athletes--detection of allogeneic blood transfusions by flow cytofluorometry

Athletes may undergo blood transfusion to increase their red cell mass and the oxygen carrying capacity of their blood in order to confer a competitive advantage. Allogeneic transfusions are normally mismatched at one or more minor blood group antigens. The most sensitive and accurate method known to detect this form of blood doping is flow cytometry. Low percentages of antigen-positive and antigen-negative red blood cells (RBCs) can be quantitated using suitable specific alloantibodies and careful analysis. By testing blood samples taken at various times, a reduction in the percentage of a minor population of RBCs will indicate transfusion has occurred.

Molecular bases of the antigens of the Lutheran blood group system

BACKGROUND

Lutheran is a complex blood group system consisting of 18 identified antigens. There are four pairs of allelic antigens, whereas others are independently expressed antigens of a high frequency. Lutheran antigens are carried by the Lutheran glycoproteins, which are a product of a single gene LU.

STUDY DESIGN AND METHODS

Genomic DNA from 21 individuals of 12 Lutheran phenotypes was used for PCR amplification of selected LU exons that were directly sequenced and compared to control DNA of a common Lutheran phenotype.

RESULTS

Lutheran phenotypes were mostly caused by single-nucleotide polymorphisms within LU, resulting in single amino acid changes. The following mutations were observed: in LU:-4, G524A, Arg175Gln; in LU:-5, G326A, Arg109His; in LU:-6,9, C824T, Ser275Phe; in LU:-8,14, T611A, Met204Lys; in LU:-13, three point mutations (C1340T, Ser447Leu, C1671T silent mutation for Ser557 and A1742T, Gln581Leu); in LU:-16, C679T, Arg227Cys; in LU:-17, G340A, Glu114Lys; and in LU:-20, C905T, Thr302Met. Two LU:-12 samples had differing results: one individual had a deletion 99GCGCTT, Arg34 and Leu35, whereas the second LU:-12 sample had a point mutation G419A, Arg140Gln.

CONCLUSION

The results revealed the genetic background of 11 Lutheran antigens and suggested their placement on the Lutheran glycoprotein.

An automatable format for accurate immunohematology testing by flow cytometry

BACKGROUND

Current immunohematology testing methods have limitations including cost, throughput, and adaptability to automation. Furthermore, current automated and semiautomated workstations cannot accommodate many other tests relevant to blood transfusion.

STUDY DESIGN AND METHODS

Authentic clinical samples from hospitalized patients were tested for ABO group, D type, and presence of RBC alloantibodies by column agglutination technology (CAT), standard tube methods, and a recently developed flow cytometry (FC) technique. Included were challenging samples with rouleaux, autoantibodies, mixed-field reactions, and weak antibodies. Antibody staining of RBCs for FC was initially performed in test tubes and subsequently in microtiter filter plates interfaced with a vacuum manifold.

RESULTS

When antibody staining was performed in tubes, FC testing determined the correct ABO group and D type for 99.1 percent of 222 clinical samples, as compared to accuracies of 91.9 percent for CAT and 95.0 percent for standard tube testing. FC testing also detected 99.5 percent of clinically relevant RBC alloantibodies in 239 patient samples, as compared to 98.9 percent for CAT and 94.7 percent for LISS-IAT. Using the FC filter plate technique, 104 of 109 samples (95.4%) were correctly typed for ABO and D (the remaining five samples were read as "no type determined" due to RBC and serum testing discrepancies), and RBC alloantibodies of the IgG and IgM classes were correctly identified in 98.3 percent of samples.

CONCLUSIONS

Optimized FC testing methods that are comparable in accuracy to standard CAT and tube methods are described. When used with filter plates, this methodology should allow rapid and cost-effective immunohematology testing of both patient and donor samples in an automated workstation format. The same workstation should support automation of other pretransfusion assays that can be analyzed by FC.

The rare Lu:-6 phenotype in Israel and the clinical significance of anti-Lu6

BACKGROUND

Lu6 is a high-incidence antigen of the Lutheran blood group. Examples of anti-Lu6 are rare and are of uncertain clinical significance.

CASE REPORT

Three patients were encountered in whom anti-Lu6 was detected on pretransfusion screening. The patients were all Iranian Jews and were not known to be related. In vitro studies to ascertain the potential clinical significance of the antibody using the monocyte monolayer assay (MMA) were negative in two patients. The third patient received a two-unit transfusion of incompatible Lu6 RBCs with no signs of hemolysis. However, after the transfusion, the MMA and a chemiluminescence test were positive, whereas a chromium survival study was normal. Thus, the antibody may have changed in its clinical significance.

CONCLUSION

Although anti-Lu6 does not appear to be a clinically significant RBC antibody in all circumstances, transfusion of Lu6 RBCs in patients with anti-Lu6 should be performed cautiously.

Flow cytometric determination of RBC survival in autoimmune hemolytic anemia

BACKGROUND

In cases of warm autoimmune hemolytic anemia (WAIHA), crossmatch incompatible RBCs are most often used for transfusion. The determination of the in vivo survival of transfused and autologous RBCs in WAIHA is helpful in the assessment of the efficacy of transfusion and other therapeutic interventions.

CASE REPORT

A 38-year-old man presented with acute WAIHA, thrombocytopenia, and neutropenia. Steroids and IVIG therapy were ineffective, and the patient received RBCS: Because of increasing hemolysis and persisting thrombocytopenia, splenectomy was performed, resulting in partial remission. Further improvement was achieved by immunosuppressive therapy.

MATERIALS AND METHODS AND RESULTS

Survival of transfused and autologous RBCs was determined, using a flow cytometric method based on the determination of different blood group antigens of patient and donor RBCS: The survival of autologous and transfused RBCs before splenectomy was determined on two consecutive days. The life span of autologous RBCs remained rather stable at 69 and 64 hours on Days 10 and 11, respectively, whereas the life span of transfused RBCs decreased from 186 hours to 25 hours. After splenectomy, the life span of transfused RBCs almost normalized: 43 days at postsplenectomy Day 3 and 87 days at postsplenectomy Day 69.

CONCLUSION

Flow cytometry was successfully used to determine changing hemolytic activity during the clinical course of WAIHA. Additionally, the survival of transfused RBCs could be measured, which may be helpful to judge for the compatibility of allogeneic RBCS: Thus, we were able to show the therapeutic inefficacy of steroids and immunoglobulins, and quick improvement after splenectomy.

Comparison of flow cytometric assays with isotopic assays of (51)chromium-labeled cells for estimation of red cell clearance or survival in vivo

BACKGROUND

A comparison was made between flow cytometric and conventional radioisotopic assays in the determination of the clearance or survival of small volumes of (51)chromium-labeled D+ red cells after injection into volunteers.

STUDY DESIGN AND METHODS

Four clearance studies were performed using 4 mL of autologous D+ cells coated with anti-D at two concentrations (5 or 10 microg anti-D/mL red cells) transfused to two subjects at separate times. Five survival studies were carried out using 5 mL of frozen-thawed D+ cells transfused to five D- subjects with no detectable anti-D. Sequential blood samples were taken for gamma counting and flow cytometry. Several methods were used to stain the transfused red cells, and the data were analyzed by using three flow cytometers.

RESULTS

The determination of red cell clearance or survival by radioactivity measurements gave results consistent with published data. However, none of the flow cytometric assays exhibited the necessary sensitivity or accuracy in quantitation of the rare events to provide reliable data for the calculation of the initial clearance rate, the red cell half-life, or the mean cell lifespan, although rough estimates of red cell clearance were obtained in some subjects. This inability to accurately enumerate rare fluorescence-labeled cells was due mainly to the presence of "background" events, which were a considerable problem in some samples, when the coating level of anti-D was less than 3000 molecules of IgG per cell.

CONCLUSION

Flow cytometry may enable the crude estimation of the percentage of small volumes (<5 mL) of transfused D+ red cells, but in this study it was found that this method was not sufficiently accurate to determine the initial clearance rate, red cell half-life, or mean cell lifespan. If the proportion of transfused cells in the recipient is about 0.2 percent or less, the use of radioisotopes for labeling cells for quantitative in vivo red cell clearance or survival data should remain the method of choice.

Significance of anti-LU8 in pregnancy

Anti-LU8, an antibody defining a high-frequency antigen in the Lutheran system, was identified in the serum of a gravida 4 para 0 pregnant women who had never been transfused. The antibody consisted of both an IgM and an IgG1 component and was nonreactive in the antibody-dependent cell-mediated cytotoxicity (ADCC) assay. The red cells of the mother and 3 siblings of the patient typed as LU:8,14 and were incompatible with the patient's serum. The baby was born at term with a negative direct antiglobulin test and typed as LU:8,14. There was no clinical evidence of haemolytic disease of the newborn.