Search

Background: Kell is a complex blood group system comprising 35 antigens. Kell antigens are absent from rare red cells of the Ko (null) phenotype and expressed only weakly in the Kmod phenotype. Molecular analysis of three uncommon KEL alleles elucidated the obscure pattern of inheritance of Kell antigens in one family., Materials and Methods: Standard serological methods were employed. All exons, flanking intronic sequence and introns 15 and 16 of KEL were sequenced from genomic DNA. cDNA was obtained from erythroid cells cultured from progenitor cells isolated from peripheral blood., Results: The Kmod propositus was heterozygous for two KEL mutations: c.2107G>A, p.Gly703Arg and a synonymous mutation, c.1719C>T, in the codon for p.573Gly. Sequencing of cDNA revealed that c.1719C>T caused skipping of exon 16, resulting in a silent allele. Her KEL:3,-4 brother was heterozygous for KEL*03/04 and c.1719C/T., Conclusion: A synonymous mutation caused complete exon skipping, despite being located 16 bases downstream of the 3′ splice site, resulting in a null KEL allele. The combined effects of two mod alleles, one responsible for KEL3 expression and the other for p.Gly703Arg, were probably responsible for an unexpected KEL:3,-4 phenotype.

Objective: To evaluate neonatal outcome in Kell haemolytic disease compared to Rh D haemolytic disease., Study Design: Retrospective study of all (near)-term neonates with Kell (n=34) and Rh D haemolytic disease (n=157) admitted to our centre between January 2000 and December 2008. We recorded the need for exchange transfusion and top-up transfusions up to 3 months of age., Results: Neonates in the Kell group required less days of phototherapy than neonates in the Rh D group [2.4 vs. 4.1 days, respectively (P<0.01)]. The percentage of neonates requiring an exchange transfusion was lower in the Kell group than in the Rh D group [6% (2/34) and 62% (98/157), respectively (P<0.01)]. The percentage of neonates in the Kell group and Rh D group requiring a top-up transfusion was 62% (21/34) and 72% (113/157), respectively (P=0.20). The median number of top-up transfusions per neonate in the Kell group and Rh D group was 1 [interquartile range (IQR) 0-2] and 2(IQR 0-2), respectively (P=0.07)., Conclusion: Neonates with Kell haemolytic disease require less phototherapy and less exchange transfusions compared to neonates with Rh D haemolytic disease, but an equal number of top-up transfusions., (© 2010 The Author(s). Vox Sanguinis © 2010 International Society of Blood Transfusion.)

Background and Objectives: Antibodies to antigens in the Kell blood group system, especially anti-KEL1, are involved in both haemolytic disease of the newborn and foetus and haemolytic transfusion reactions. Correct typing results are important and discrepancies between serologic and genetic typing must be resolved. Here, we describe the investigation of three healthy individuals who were initially phenotyped as KEL:1,-2., Materials and Methods: Antigen typing was performed by standard serological techniques and by flow cytometric analysis. The KEL*01/02 polymorphism was tested by an allele-discrimination TaqMan assay as well as by PCR with allele-specific primers and PCR-RFLP. DNA sequencing of the KEL coding region was also performed., Results: Two KEL*02N alleles with mutated splice sites around exon 8 were identified: intron 7 -1g>c (novel) and intron 8 +1g>t (previously reported in one case of K(0)). In the third sample, a missense mutation in exon 8, 787G>A (novel) predicting Gly263Arg, was detected on a KEL*02 allele and associated with dramatically weakened KEL2 antigen expression., Conclusion: Resolution of discrepant phenotype/genotype results identified silencing mutations in or around exon 8. A combination of molecular and serologic methods has the potential to improve the quality of test results and was required to ensure both the accurate KEL2 antigen status and KEL*01 zygosity of these individuals.

Background and Objectives: Kell haemolytic disease in pregnancies has been suggested to be associated with decreased fetal platelet counts. The aim of this study was to evaluate the incidence and clinical significance of fetal thrombocytopenia in pregnancies complicated by Kell alloimmunization., Materials and Methods: In this retrospective cohort study, fetal platelet counts were performed in 42 pregnancies with severe Kell alloimmunization prior to the first intrauterine blood transfusion. Platelet counts from 318 first intrauterine transfusions in RhD alloimmunized pregnancies were used as controls., Results: Fetal thrombocytopenia (platelet count < 150 x 10(9)/l) was found in 4/42 (10%) in the Kell group and in 84/318 (26%) in the RhD group. None of the fetuses in the Kell alloimmunized pregnancies, including 15 with severe hydrops, had a clinically significant thrombocytopenia defined as a platelet count < 50 x 10(9)/l. In the RhD alloimmunized pregnancies, 2/230 (1%) of the non-hydropic fetuses and 7/30 (23%) of the severely hydropic fetuses had a clinically significant thrombocytopenia., Conclusion: In contrast to fetuses with severe anaemia and hydrops due to RhD alloimmunization, fetuses with severe anaemia due to Kell alloimmunization are generally not at risk for substantial thrombocytopenia.

Background and Objectives: Kell antigens are encoded by the KEL gene on the long arm of chromosome 7. Kx antigen is encoded by the XK gene on the short arm of the X chromosome. Kell and Kx proteins in the red cell membrane are covalently linked by a disulphide bond. The McLeod phenotype is characterized by weakened expression of antigens in the Kell blood group system, absence of Km and Kx antigens, and acanthocytosis. It has an X-linked mode of inheritance with transmission through carrier females. Some males with the McLeod syndrome also have chronic granulomatous disease (CGD). It is generally believed that patients with non-CGD McLeod may develop anti-Km but not anti-Kx, but that those with CGD McLeod can develop both anti-Km and anti-Kx., Materials and Methods: We present serological data, DNA genotyping and gene sequencing, monocyte monolayer assay and neutrophil oxidative burst test from a patient with the McLeod phenotype without clinical evidence of CGD., Results: We report here the second example of a patient with non-CGD McLeod who developed anti-Kx in addition to anti-Km. Sequencing of our patient's XK gene confirmed the presence of a mutation resulting in a premature stop codon and lack of Kx protein in the red cell membrane, which is consistent with the diagnosis of McLeod syndrome. Neutrophil oxidative burst test was normal, indicating that our patient did not have CGD. The challenge of providing 10 compatible blood units for multiple surgeries was met., Conclusion: The second case of a rare entity, a patient with non-CGD McLeod who developed anti-Kx and anti-Km, was managed successfully with a combination of autologous donations and procurement of compatible units from national and international sources.

Background and Objectives: The molecular basis of two Kell blood group antigens, RAZ (provisionally KEL27) and VLAN (KEL25), were determined., Materials and Methods: The DNA sequences of the open reading frames and the flanking intron regions of the 19 KEL exons from RAZ and VLAN probands were compared with that of common KEL. Genotyping assays were designed to confirm and detect RAZ and VLAN phenotypes., Results: A homozygous G865A mutation, encoding lysine instead of glutamic acid at amino acid position 249 of Kell protein, defines the RAZ phenotype, while a heterozygous G863A mutation in KEL, encoding an arginine to glutamine substitution at amino acid 248, characterizes the VLAN phenotype., Conclusion: Point mutations G865A and G863A, in adjacent codons of KEL exon 8, which cause amino acid substitutions, characterize the RAZ and VLAN Kell blood group phenotypes.

A case of anti-Js(b) in pregnancy was associated with unexpectedly severe haemolytic disease of the newborn, requiring urgent exchange transfusion. Clinical signs of fetal distress were evident at 35 weeks of gestation in a sixth pregnancy. A Js(b+) baby from a previous pregnancy had been unaffected. This case report illustrates the difficulties of predicting severity on the basis of anti-Js(b) titre, and highlights issues relating to the problems of using reconstituted frozen red cells from the rare red cell bank for exchange transfusion.

Antenatal genotyping of the fetus is now in widespread use as an aid to the clinical management in cases where there is the potential of haemolytic disease of the newborn occurring. The rapid diagnosis of an antigen-negative fetus will preclude the requirement for further, potentially risky invasive procedures being performed, whilst the determination of an antigen-positive fetus allows the potential of intensifying obstetric care for this pregnancy. Molecular genotyping is a major clinical application which has led from the determination of the molecular bases of blood group antigens expressed, most of which have been defined at the level of the gene. All assays used are dependent on the Polymerase Chain Reaction amplification of fetal DNA derived from either amniotic fluid or chorionic villi. Recent work has explored the potential of utilising fetal cells found to be present in maternal peripheral blood as a source of nucleic acid for prenatal diagnosis. Using non-invasive methods will preclude exposing mother and fetus to the potential hazards of invasive methods (amniocentesis, chorionic villus sampling and cordocentesis) which include miscarriage, fetal malformations and further maternal alloimmunisation.

Background and Objectives: The clinical significance of anti-K11 in red cell transfusion therapy is unknown. We report the outcome of transfusion of K:11 erythrocytes into a patient with a known anti-K11 antibody., Materials and Methods: The patient was monitored clinically following transfusion of 11 units of K:11 erythrocytes. A red cell survival study with K:11 erythrocytes and a monocyte monolayer assay (MMA) were performed., Results: No adverse clinical outcome was detected. The red cell survival study showed normal survival of K:11 erythrocytes, and the MMA showed no increase in reactive monocytes., Conclusion: These findings suggest that K:11 red cells can safely be transfused to individuals with anti-K11 antibody.

The molecular basis of different Kell blood group phenotypes is reviewed. Sequence analysis of the Kell gene (KEL) established that single base substitutions, resulting in amino acid changes, are responsible for the different phenotypes. Most of the amino acid substitutions, with the exception of the one responsible for expression of KEL6 (Jsa), occur at the amino-terminal half of the protein, a domain that has least amino acid homology with a family of zinc endopeptidases, which include neutral endopeptidase 24.11 and endothelin-converting enzyme-1. Some of the genes were expressed in transfected cells and typed with alloantibodies to confirm that the identified mutations are responsible for antigen expression. Clinical applications of Kell blood group genotyping which include prenatal diagnosis to monitor hemolytic disease of the newborn are discussed.

A multilaboratory investigation has identified a new low-incidence antigen "VLAN' on the red cells of a blood donor. The VLAN antigen is destroyed by 2-aminoethylisothiouronium bromide treatment of the donor's red cells suggesting an association with the Kell system. Monoclonal antibody-specific immobilization of erythrocyte antigen analysis with anti-VLAN and with several mouse monoclonal antibodies directed at epitopes on the Kell glycoprotein gave positive results, indicating that the VLAN antigen is located on the Kell glycoprotein. The VLAN red blood cells have the common Kell phenotype: KEL:-1,2,-3,4,5,-6,7,-10,11,12,13,14,-17,18,19,-21,22,-23,-24. Additional serologic data indicate that the VLAN antigen is not part of any other ISBT blood group system, collection or series. A family study showed that the VLAN antigen is inherited since the red cells of two sisters and one niece of the propositus are also VLAN+. The ISBT Working Party on Terminology for Red Cell Surface Antigens has assigned VLAN to the Kell blood group system as KEL25 (number for computer listings 006025).

Autoimmune haemolytic anaemia (AIHA) in infancy is rare. We report a case of AIHA in a male infant whose serum contained an antibody with apparent anti-Kpb specificity. Autoantibody with anti-Kpb specificity has been described in adults; to our knowledge, this is the first case of this kind described in infancy with AIHA. Clinical course and response to red cell transfusion are described.

A 47-year-old native American (TOU) was admitted to hospital for hip surgery. His serum agglutinated all red blood cells (RBCs) tested except Ko and DTT-treated RBCs and was weakly reactive with RBCs known to have a weak expression of Kell antigens, namely Kmod, McLeod, Kp(a+b-) (KEL:3,-4) and K:-13 (KEL:-13) phenotypes. RBCs from three siblings, a son and a daughter were incompatible with TOU's antibody. TOU's RBCs had the common Kell phenotype: K-k+Kp(a-b+c-)Ku+Js(a-b+)Ul(a-)K:11,-17K:14,-24K:12,13,18,19, 22,-23(KEL:-1,2,-3,4,5,-6,7,-10,11,12,13,14,-17,18,19,-21,22,-23,-24). Since TOU's RBCs were not agglutinated by an unidentified Kell-related antibody (IAN), tests were performed to show that TOU and IAN were mutually compatible. IAN is a Latino female hospitalised for a hysterectomy. The TOU antigen was shown to be located on the Kell glycoprotein by a monoclonal antibody immobilisation of erythrocyte antigen (MAIEA) assay. The unique pattern of reactivity obtained with TOU and IAN antibodies using this assay indicated the TOU epitope to be in an area remote from other Kell antigens, namely K, k, Kpa, Kpb, Kpc, Ku, Jsa, Jsb, U1a, K11, K12, K13, K14, Wka, K18, K19, K22 and K24 (KEL1, KEL2, KEL3, KEL4, KEL5, KEL6, KEL7, KEL11, KEL12, KEL13, KEL14, KEL17, KEL18, KEL4, KEL5, KEL6, KEL7, KEL11, KEL12, KEL13, KEL14, KEL17, KEL18, KEL19, KEL21, KEL22 and KEL24) but close to the low-incidence antigen K23 (KEL23).(ABSTRACT TRUNCATED AT 250 WORDS)

K12 is a high-prevalence antigen, with no known antithetical partner, that is associated with the Kell blood group system. We report studies on the 5th propositus (MS) with the K:-12 phenotype and the second case to show that the K12 is inherited. The anti-K12 in his serum did not destroy antigen-positive incompatible red cells transfused on at least 3 occasions over 6 years. Red cell membranes from MS possessed the Kell protein that was indistinguishable from control membranes. K12 antigen was shown by immunoprecipitation to be on a protein with an apparent molecular mass of 93,000 and by monoclonal antibody immobilization of erythrocyte antigens (MAIEA) assay to be on the Kell protein in proximity to K/k and Jsa/Jsb antigens. These data remove the K:-12 phenotype from its current Kell-related (or para Kell) status and elevates the K12 antigen to a bona fide member of the Kell blood group system.

Anti-Js(b) has not been reported to cause severe hemolytic disease of the newborn requiring intrauterine evaluation and treatment. We now report on such a patient with high-titered anti-Js(b) causing fetal hydrops with demise in one pregnancy, followed by a pregnancy treated with multiple intrauterine fetal transfusions.

The first case of hemolytic disease of the newborn (HDN) due to anti-Ula antibodies is described. The infant had severe anemia with a positive direct antiglobulin test with anti-IgG that required blood transfusion. But jaundice was not severe enough for exchange transfusion or phototherapy.

We report a case of clinically significant hemolytic disease of the newborn due to Kpb alloimmunisation requiring obstetric intervention. This case and a review of the literature are in contrast to reviews of hemolytic disease of the newborn that either ascribe no significance to the Kpb antigen or suggest that it causes only rare or mild disease. Analysis of our Kpb-negative donor pool suggests that prior transfusion greatly increases the chance of alloimmunisation. The role of frozen rare donor registry cells as a public resource is emphasised.

The case of a 58-year-old male with severe anemia after hemicolectomy is described. The patient proved to be Kp(b-), and the serum contained anti-Kpb. Because no Kp(b-) donors were available, two incompatible units are administered after intravenous gammaglobulin (400 mg/kg/day) and hydrocortisone (500 mg). The tolerance was good, without signs of increased red cell destruction. Pending the arrival of compatible blood from the American Red Cross, the hematocrit reached 18%, and the direct antiglobulin test remained negative.

Red cells of the McLeod phenotype in the Kell blood group system have an acanthocytic morphology. The membrane protein composition analyzed on sodium dodecyl-sulfate-polyacrylamide gel electrophoresis, the ATP level and the activities of a large number of intracellular enzymes appear to be normal. Membranes prepared from McLeod red cells incubated with gamma AT[32P] and MgCl2 incorporated twice as much radioactivity into spectrin and also showed a slight elevation of phosphorylation in band 3 protein when compared to membranes from normal cells. Intact normal red cells incubated with carrier-free [32P] incorporated radioactivity into several proteins, with most incorporation in spectrin and band 3 protein. In comparison, McLeod cells incorporated three times more radioactivity into spectrin and band 3 protein but increased phosphorylation also occurred in other, but not all, membrane proteins. Intact McLeod red cells also showed increased phosphorylation of membrane phospholipids, but they incorporated [32P] into intracellular nucleotide phosphates in a normal manner.

An example of auto-anti-Kpb in a Kp(a+b-) patient is described. The antibody present in the patient's serum and in eluates from her red cells was IgG. It did not bind complement, and did not cause in vivo hemolysis. 9 months after recognition of the autoimmune state the direct antiglobulin test had become negative and anti-Kpb was no longer detectable. It is postulated that autoimmunity involving the Kell blood group may be precipitated by antigens or enzymes of microbial origin.

Random typing of donor units revealed a donor whose red blood cells gave very weak reactions with all anti-Kell (anti-K1) antisera. All other Kell-system antigen was present in four generations of the donor's family. The red-cell morphology is normal in all family members with the weakened K1 antigen. A consistent hypothesis is that the weak antigen is inherited through a variant allele at the Kell locus and represents a quantitative, not a qualitative, change.

An alloantibody is described which detects a high frequency blood group antigen absent from Ko cells but different from all the reported Kell and para-Kell antigens. The family study shows the antigen to be inherited but gives no information about its relationship to the Kell locus. It is suggested that this 'new' para-Kell antigen be called K22.

We report an instance of transfusion-induced anti-k so severe that three intrauterine intravascular fetal transfusions were required. The pretransfusion circulating hemoglobin level in the fetus was 60 g/l and hematocrit was 0.19. This, to our knowledge, is the first example of the rare alloantibody, anti-k, producing erythroblastosis so severe that fetal transfusions were required in order to prevent hydrops fetalis from developing. Anti-k alloimmunization, which in a period of 20 years and 8 months occurred only once in 3,246 alloimmunized pregnancies in Manitoba, can cause severe fetal disease. The k-alloimmunized pregnant woman should be managed in the same manner as the D-, c-, or K-alloimmunized pregnant woman.

An example of a cold-reacting IgM anti-K2 is described. The patient has a history of blood transfusion and two pregnancies. It is, therefore, not possible to differentiate between natural occurrence or immune stimulation as an explanation of this antibody's presence. In 1966, Thomas and Konugres reported an unusual example of anti-K2 composed entirely of IgM and reacting optimally at 20 degrees C, although some reactions at 37 degrees C were observed. We wish to report a further example which does not react at 37 degrees C.

Mouse hybridoma clones have produced monoclonal antibodies directed against the K:14 and K:2 high-incidence antigens of the Kell blood group system. Two examples of anti-K14 were isolated, each arising from a separate fusion procedure. All three monoclonal antibodies are of the immunoglobulin class IgG1. Serological activity is consistent with that seen with human antibodies to high-incidence Kell system antigens, and their epitopes are destroyed, as usual, by 2-aminoethylisothiuronium bromide treatment. Specificity was further confirmed by adsorption and elution studies. Tests against nonhuman primate red cells demonstrated the expression of K:14 only by the great apes, whereas K:2 was present on all red cells tested. These findings emphasize the usefulness of monoclonal antibodies to elucidate the evolutionary patterns of blood group variants.

The second example of anti-K22 was found, like the first, in an Iranian Jew living in Israel. The consanguineous parents of the propositus were both K+k+, and investigation of the family suggested that K22 is controlled by the Kell locus; K travelling with K22 and k with K-22.

A major delayed hemolytic transfusion reaction produced by an antibody to Lewisb is reported. Delayed hemolysis following transfusion with Leb-positive red cells was not reported to the blood bank. Severe hemolysis recurred following a second transfusion with Leb-positive cells, but was avoided thereafter with Leb-negative red cells. This is the first reported case of a serious delayed hemolytic transfusion reaction caused by anti-Leb.

A unit of whole donor blood, the plasma of which contained anti-Kell antibody, was transfused into a Kell-negative patient who had received a unit of Kell-positive blood 4 weeks previously. A haemolytic transfusion reaction ensued. The antibody had gone undetected in routine automated screening of the donor blood. Automated antibody detection techniques do not offer reliable detection of anti-Kell antibodies.

Autoantibodies the specificity of which mimicks Kpb specificity are described in a patient whose phenotype is Kp(a+b-). Manual typing of the patient's red cells revealed a depression of the Kell-related antigens. However, this weak reactivity was not found in the Autoanalyzer using bromeline PVP, the percentage of agglutination being similar to that of red cells of normal blood donors. Alloanti-K antibodies were present in the patient's serum. The specificity of the autoantibodies was considered to be mimicking because they could be absorbed by and eluted from Kpb- and Ko (AET-treated) red cells.