The outcome of pregnancy in Kell alloimmunisation

OBJECTIVE

To assess management and outcome of pregnancies with anti-Kell in the West Midlands in the UK over 13 years.

DESIGN

A retrospective review of casenotes.

SETTING

A regional referral clinic for red cell alloimmune disease and fetal medicine unit at a university hospital.

POPULATION

Sixty-five pregnancies were identified in 52 Kell-sensitised women with Kell positive partners from the records of the Birmingham Blood Transfusion Centre.

METHODS

Information from the casenotes was entered on a database and comparisons were made using the SPSS for Windows statistics package.

MAIN OUTCOME MEASURES

Mode of sensitisation, degree of fetal or neonatal anaemia, need for transfusion, gestation at delivery, birthweight and pregnancy outcome.

RESULTS

Alloimmunisation was transfusion-related in 29 pregnancies and pregnancy-induced in 33. The cause could not be identified in three cases. There were 22 proven Kell positive fetuses, of which 18 were affected, in which alloimmunisation was pregnancy-related in 12 cases and transfusion-related in five. Antibody titres and amniotic fluid OD450 were not helpful in management. Severe or very severe disease occurred in 50% of the affected pregnancies (9/18). There was no difference in pregnancy outcome between transfusion or pregnancy induced sensitisation.

CONCLUSIONS

Anti-Kell alloimmunisation is an uncommon cause of serious anaemia in a significant proportion of affected pregnancies. There appears to be no difference between that caused by pregnancy or transfusion. Estimation of fetal haemoglobin concentration by cordocentesis is recommended, as antibody titres and amniocentesis are not helpful.

[Prevention, diagnosis and treatment of blood group immunization during pregnancy]

In the Netherlands last year two important policy changes were introduced to prevent haemolytic disease of the newborn: antenatal administration of anti RhD immunoglobulin and screening for antibodies against irregular erythrocyte antigens in all pregnant women. As the predictive value of such antibodies for the detection of hemolytic disease of the newborn is limited, it is uncertain if this measure is really cost-effective. Because blood transfusion is the most important probable cause of the immunization, and because of the clinical severity of anti-K antibodies, it is advised to give exclusively K negative blood to girls and women under the age of 45 years. In addition there is a need for a uniform protocol to deal with women who have been exposed to immunization.

Intracellular assembly of Kell and XK blood group proteins

Kell, a 93 kDa type II membrane glycoprotein, and XK, a 444 amino acid multi-pass membrane protein, are blood group proteins that exist as a disulfide-bonded complex on human red cells. The mechanism of Kell/XK assembly was studied in transfected COS cells co-expressing Kell and XK proteins. Time course studies combined with endonuclease-H treatment and cell fractionation showed that Kell and XK are assembled in the endoplasmic reticulum. At later times the Kell component of the complex was not cleaved by endonuclease-H, indicating N-linked oligosaccharide processing and transport of the complex to a Golgi and/or a post-Golgi cell fraction. Surface-labeling of transfected COS cells, expressing both Kell and XK, demonstrated that the Kell/XK complex travels to the plasma membrane. XK expressed in the absence of Kell was also transported to the cell surface indicating that linkage of Kell and XK is not obligatory for cell surface expression.

Structure and expression of the mouse homologue of the XK gene

The human Kx blood group antigen is carried by a 37,000 M(r) apparent molecular mass membrane polypeptide which is deficient in rare individuals with the McLeod syndrome. The X-linked human XK gene is transcribed in many tissues including adult skeletal muscle and brain, sieges of disorders observed in McLeod syndrome. We report here the cloning of the orthologous mouse XK mRNA. Comparison of XK from human and mouse revealed 80% sequence similarity at the amino acid level. The mouse XK gene is organized in two exons and is expressed in many tissues, but its expression pattern is slightly different from that of the human gene. The presence in mouse erythrocyte membrane of a 43,000 M(r) Kx-related protein was demonstrated by immunoblotting with a rabbit antiserum directed against the human protein. With non-reduced samples, a 140,000 M(r) species was detected instead of the 43,000 M(r) protein, suggesting that, as demonstrated in the Kx polypeptide might be complexed with another protein in mouse red cells, presumably the homologue of the human Kell protein of 93,000 M(r).

A case for comprehensive antenatal screening for blood group antibodies

OBJECTIVES

To determine the frequency of various blood group antibodies responsible for haemolytic disease of the new born (HDN).

DESIGN

A prospective study of all neonates and still born foetuses suspected to have haemolytic disease of the new born and their mothers.

SUBJECTS

Neonates suspected to have HDN as per study criteria along with their mothers and mothers of still born foetuses with hydrops foetalis.

METHODS

Pertinent serological tests, serum bilirubin estimation, haemoglobin estimation and reticulocyte count on neonate's blood samples and demonstration/titration of blood group specific antibodies in maternal blood samples.

RESULTS

Six cases of HDN due to blood group antibodies were detected so far. Four were due to anti-D and all were of mild severity as per study criteria. Two cases were of severe haemolytic disease (hydrops foetalis). Both were due to anti Kell. Both women had history of previous blood transfusion and abortions.

CONCLUSION

Comprehensive antibody screening should be performed during antenatal period in women who have received blood transfusion and/or have history of un-explained abortions.

[The effect of ABO, Rhesus and Kell blood group antigens on gallstone prevalence. A sonographic study of 1030 blood donors]

BACKGROUND AND OBJECTIVE

Besides generally accepted risk factors of the pathogenesis of gallstone disease such as age, obesity, female sex and high number of births, hereditary factors are held responsible for different prevalence rates. A number of studies dealt with the question of a correlation between the prevalence of gallstone disease and different blood groups. The Ulm Gall Bladder Stone Study represents the first sonographic prospective study regarding this issue.

SUBJECTS AND METHODS

Unselected blood donors (n = 1030, 606 men, mean age 38.0 years, 424 women, mean age 34.1 years) were sonographically examined for presence of gallstones at the German Red Cross blood donor centre in Ulm. Besides AB0, Rhesus and Kell blood group anthropometric data of the test subjects were recorded by means of a semi-standardized interview.

RESULTS

The prevalence of gallstone disease in all test subjects was 6.0%. Within the AB0 system the prevalence in subjects with blood group AB was highest (12.1%). The prevalence in Rh-positive and Rh-negative subjects was nearly identical (6.0 vs. 6.1%). Kell factor positive subjects suffered less from gallstone disease than Kell factor negative subjects (2.0 vs. 6.3%). None of these differences in prevalence were statistically significant.

CONCLUSION

This study revealed no significant correlation between the distribution of the AB0, Rhesus and Kell blood group antigens and the prevalence of gallstone disease.

Association of XK and Kell blood group proteins

A disulfide bond links Kell and XK red cell membrane proteins. Kell, a type II membrane glycoprotein, carries over 20 blood group antigens, and XK, which spans the membrane 10 times, is lacking in rare individuals with the McLeod syndrome. Kell is classified in the neprilysin family of zinc endopeptidases, and XK has structural features that suggest it is a transport protein. Kell has 15 extracellular cysteines, and XK has one in its fifth extracellular loop. Five of the extracellular cysteine residues in Kell are not conserved in the other members of the neprilysin family, and based on the hypothesis that one of the nonconserved cysteines is linked to XK, cysteines 72 and 319 were mutated to serine. The single extracellular cysteine 347 of XK was also mutated. Co-expression of combinations of wild-type and mutant proteins in transfected COS-1 cells showed that Kell C72S did not form a Kell-XK complex with wild-type XK, while wild-type Kell and Kell C319S did. XK C347S was also unable to form a complex with wild-type Kell, indicating that Kell cysteine 72 is linked to XK cysteine 347. Kell C72S was transported to the cell surface, indicating that linkage to XK is not required. In addition, chemical cross-linking of red cell membranes with dithiobispropionimidate indicated that glyceraldehyde-3-phosphate dehydrogenase is a near neighbor of Kell.

Hydrops fetalis caused by a blood group antibody usually undetected in routine screening

A case of isoimmunisation in pregnancy caused by antibodies to the Kpa red blood cell antigen is described. The preceding pregnancy had resulted in fetal hydrops for which no cause was found as the antibody screening cells used to investigate the fetal hydrops were Kpa negative. This case emphasises the importance of serological screening at a reference laboratory for low frequency red cell antigens before a diagnosis of non-immune hydrops is made.

A family of McLeod syndrome, masquerading as chorea-acanthocytosis

A man, aged 52, is reported to show (1) adult onset, (2) progressive orofacial dyskinesia and choreic movements of the extremities, (3) tongue biting, (4) denervation of the peripheral nerves, (5) acanthocytosis, and (6) increased serum creatine kinase, which are characteristic of chorea-acanthocytosis. The Kell blood group examination on erythrocytes disclosed that the propositus had McLeod phenotype, and his mother and one of his sisters were carriers of the McLeod phenotype. Thus, he was diagnosed as having McLeod syndrome. A criterion of exclusion of McLeod phenotype on erythrocytes should be added to the diagnostic criteria of chorea-acanthocytosis. Moreover, chronic neurogenic changes instead of myogenic changes were electromyographically and histopathologically verified in the muscle.

Lack of clinical significance of "enzyme-only" red cell alloantibodies

In a retrospective study on samples from 10,000 recently transfused patients, 35 samples were found to contain an antibody that reacted with ficin-treated red cells but was not demonstrable by low-ionic-strength saline solution and indirect antiglobulin test (LISS-IAT). In those 35 patients, the specificity of the antibody was such that each patient would have been transfused with antigen-negative blood had the antibody reacted in LISS-IAT. Tests on red cells from the units already transfused showed that 19 patients had among them received, by chance, 32 antigen-positive and 74 antigen-negative units. The remaining 16 patients had among them received 57 units that were, again by chance, all antigen negative. One patient given antigen-positive blood suffered a delayed transfusion reaction; in two others the antibodies became LISS-IAT active after transfusion. However, similar changes to the LISS-IAT-active state were seen with two antibodies of patients given only antigen-negative blood. Also found in the 10,000 patients were 28 clinically insignificant antibodies, 77 sera in which the antibody was too weak to identify, and 216 autoantibodies that reacted only with ficin-treated red cells. These data support a belief, generally held in the United States but not necessarily elsewhere, that the use of protease-treated red cells for routine pretransfusion tests creates far more work than the accrued benefits justify.

Maternal Kell blood group alloimmunization

BACKGROUND

Two recent paper have provided conflicting views regarding the severity of Kell hemolytic disease of the newborn.

METHODS

We reviewed our experience during 1944-1990 with pregnant Kell-alloimmunized Manitoban women and similar women referred from outside of Manitoba.

RESULTS

Between 1944-1990, 311 Kell-immunized Manitoban women had 459 pregnancies, of which 63 ended in abortion or stillbirth unrelated to anti-Kell. Of the infants born, 376 were unaffected and 20 were affected. Twelve did not require treatment; two needed phototherapy, one required a simple transfusion, and one an exchange transfusion. One died of kernicterus and three were hydropic and died; all four deaths occurred between 1948-1954. Fourteen Kell-immunized women with 16 pregnancies were referred from outside Manitoba. Eleven had a history of Kell hydropic fetuses and ten had hydropic fetuses at referral. Five of the hydropic fetuses survived and five died. Five women had Kell-negative infants correctly predicted by amniocentesis (two) and by fetal blood sampling (three). Serial amniotic fluid delta OD 450 readings were 83-89% accurate in predicting the presence and severity of Kell hemolytic disease. Life-threatening inaccuracies occurred, primarily in the early and middle second trimester.

CONCLUSIONS

Kell hemolytic disease, although rare, may be as severe as Rh(D) hemolytic disease when it does occur. When there is a history of hydrops or the father is Kell-positive and the maternal anti-Kell indirect antiglobulin titer is 8 or greater, amniocentesis should be performed at 16-20 weeks' gestation. Fetal blood sampling followed by fetal intravascular transfusion is indicated if delta OD 450 readings approach the 65% level in modified zone 2 of Liley or if amniocentesis is precluded because of an anterior placenta and there is a history of hydrops or ultrasound evidence of fetal hemolytic disease.

Reduced membrane protein methylation in red cells of the McLeod blood group phenotype

Red cells (RBCs) contain an abundance of protein methylase II, which catalyzes the transfer of methyl groups from S-adenosylmethionine to carboxyl groups of aspartyl and glutamyl residues in proteins. Enzyme-catalyzed transfer of methyl groups, labeled with 14C or 3H, from S-adenosylmethionine to membrane proteins of McLeod, Ko, and control RBCs was assayed by determining the acceptance of labeled methyl groups under standardized conditions. Membranes of control cells and Ko cells showed about 50 percent greater uptake than did those of McLeod cells. However, when ovalbumin was used as a methyl-accepting substrate, the levels of protein carboxymethyltransferase activity in all three types of cells were found not to differ significantly. In addition, no significant qualitative differences were apparent when methyl-labeled polypeptides from control and McLeod cells were separated by slab gel electrophoresis. The mechanisms responsible for changes in membrane protein methylation of McLeod cells remain unclear. However, these observations provide further evidence of the pleiotropic biochemical lesion associated with the acanthocytic morphology that characterizes McLeod RBCs.

A case of hemolytic disease of the newborn infant due to anti-K (Cellano)

Hemolytic disease of the newborn infant (HDN) due to anti-K (Cellano) is very uncommon in Caucasians. We report here a case of anti-K HDN. The anti-K alloimmunization appeared in the mother during her fifth pregnancy. This HDN needed an exchange transfusion immediately after delivery. The clinical outcome of the newborn infant was good.

Erythroblastosis fetalis produced by Kell immunization: dental findings

Erythroblastosis fetalis is a severe hemolytic disease in the newborn that originates in utero because of a maternal-fetal blood incompatibility. An unusual case of erythroblastosis fetalis caused by an irregular antibody of the Kell blood group is presented. The dental findings are compared to those found with Rh(D) incompatibility.

Hemolytic transfusion reaction due to interdonor kell incompatibility. Report of two cases and review of the literature

A 74-year-old man experienced an acute hemolytic reaction following transfusion of 4 units of red blood cells. The recipient was K negative, one of the transfused units was K positive, and another contained a previously undetected anti-K with an indirect antiglobulin titer of 512. Further investigation led to the discovery of a hemolytic transfusion reaction in a second K-negative patient who received a platelet transfusion containing 50 mL of plasma from the same donor. The clinical and serologic features of these two cases and five previously reported cases of hemolytic transfusion reaction due to interdonor Kell incompatibility are summarized.

Acanthocytosis and neurological impairment--a review

Acanthocytes have a distinct morphology and are not normally found in peripheral blood. They occur in association with at least three neurological syndromes. In abetalipoproteinaemia, a progressive spinocerebellar ataxia and retinopathy occurs secondary to malabsorption of vitamin E. Cases with chorea are often familial, with orofacial dyskinesia and an axonal neuropathy causing areflexia and muscle wasting. Areflexia and a subclinical myopathy also occur in the McLeod syndrome, in which there is abnormal expression of Kell blood group antigens. The exact mechanism of acanthocytosis in each disorder remains uncertain: passive changes in membrane lipids, surface receptor/ligand interactions, and a primary membrane defect are among the possibilities.

Anaphylaxis to human serum albumin

During her 26th week of pregnancy a 20-year-old woman developed generalized pruritus, urticaria, flushing, tinnitus, and tachycardia during plasmapheresis with 5% human serum albumin (HSA) as adjunctive treatment for anti-Kell isoimmunization. The reaction was controlled with intravenous diphenhydramine. Despite pretreatment with diphenhydramine and betamethasone a subsequent attempt to perform plasmapheresis with infusion of 5% HSA resulted in a more severe reaction which progressed to respiratory distress. Intradermal skin testing with 5% HSA produced a 9 x 11-mm wheal and 17 x 21-mm erythema at 15 minutes. An enzyme-linked immunoassay was positive for IgE antibody to 5% HSA before and after dialysis for removal of Na caprylate. These results are consistent with an IgE-mediated basis for this patient's reaction to HSA.

Clinical concepts of Duchenne muscular dystrophy. The impact of molecular genetics

Molecular genetics has transformed clinical concepts of Duchenne muscular dystrophy (DMD) in several different ways. (1) The disease can now be defined as a myopathy due to mutation at Xp21, a specific locus on the short arm of the X chromosome. (2) As a consequence of that discovery, any myopathy due to mutation at Xp21 should be a variant of DMD and should affect the same gene product. Moreover, any myopathy due to mutation at a location other than Xp21 should affect some other gene product. (3) For these reasons, DNA analysis is now needed for clinical diagnosis of muscle disease. (4) Xp21 myopathies may be mild or severe, may occur in females even though X-linked, and may be manifest only by high serum levels of creatine kinase. (5) Mental retardation is not consistently related to diseases that are encoded at Xp21. The association of mental retardation with DMD may be due to mutation in a separate gene near that for DMD. Concepts may soon be altered again as we learn about the affected gene product (dystrophin) and its role in these diseases.