The increasing need for ABO blood group genotyping and quality assurance implications for laboratory implementation

ABO blood group antigens are critical determinants of immunologic self and non-self and are ubiquitously expressed on all cellular tissues. Antibodies against non-self ABO antigens are naturally present and can mediate pathologic reactions against incompatible transfused blood cells and transplanted tissues. Laboratory testing for ABO antigens and isoagglutinins is essential for safe and effective transfusion and transplantation. Testing for ABO antigens has traditionally depended on serologic testing. However, there is increasing need for evaluation of genetic analysis of ABO antigens, to enable evaluation of ABO blood group in cases where serologic testing may be ambiguous or impossible to accurately perform. The clinical need for ABO genotyping is being addressed by the development of multiple molecular diagnostic approaches. Recent data have clearly demonstrated the potential utility of ABO genotyping in solid organ transplantation, yet widespread implementation has been slow. We propose that this lag is related to practical considerations in laboratory testing, including limited regulatory guidance on the performance and reporting of these assays and the absence of widely available external proficiency testing programs for quality assurance. Here we describe approaches to ABO genotyping, current initiatives in developing ABO genotyping proficiency testing programs, and laboratory quality assurance considerations for ABO genotyping.

Passenger lymphocyte syndrome in ABO and Rhesus D minor mismatched liver and kidney transplantation: A prospective analysis

The increasing demand for solid organs has necessitated the use of ABO and Rhesus (Rh) D minor mismatched transplants. The passenger lymphocyte syndrome (PLS) occurs when donor lymphocytes produce antibodies that react with host red blood cell (RBC) antigens and result in hemolysis. Our aim was to evaluate prospectively the role of PLS in post transplant anemia and hemolysis in ABO and RhD minor mismatched recipients of liver and kidney grafts and to study the association of PLS with donor lymphocyte microchimerism. We examined 11 liver and 10 kidney recipients at Day +15 for anemia, markers of hemolysis, direct antiglobulin test and eluates, and serum RBC antibodies. Microchimerism was determined in peripheral blood lymphocytes by genotyping of simple sequence length polymorphisms encoding short tandem repeats. Immune hemolytic anemia and anti-recipient RBC antibodies were observed in 2 out of 11 liver (18.2%) and 2 out of 10 kidney (20%) transplants. RBC antibody specificity reflected the donor to recipient transplant, with anti-blood group B antibodies identified in 2 cases of O to B and 1 case of A to AB transplants while anti-D antibodies were detected in 1 case of RhD-negative to RhD-positive transplant. Donor microchimerism was found in only 1 patient. In conclusion, passenger lymphocyte mediated hemolysis is frequent in minor mismatched liver and kidney transplantation. Recognizing PLS as a potential cause of post transplant anemia may allow for early diagnosis and management to decrease the morbidity and mortality in some patients.

Risk estimation of HNA-3 incompatibility and alloimmunization in Thai populations

Severe transfusion-related acute lung injury (TRALI) is often due to antibodies in blood components directed against human neutrophil antigen (HNA)-3a. This study aimed to report the genotype frequencies of the HNA-3 system and to estimate the potential risk of HNA-3 incompatibility and alloimmunization in two Thai populations. Eight hundred DNA samples obtained from 500 unrelated healthy blood donors at the National Blood Centre, Thai Red Cross Society, Bangkok and 300 samples from the Blood Bank, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand were included. HNA-3 genotyping was performed using an in-house polymerase chain reaction with sequence-specific primer (PCR-SSP) technique. The observed frequencies of the HNA-3a/3a, HNA-3a/3b, and HNA-3b/3b genotypes were 0.528, 0.380, and 0.092 in central Thais and 0.600, 0.350, and 0.050 in northern Thais, respectively. The frequencies were used to estimate HNA-3 incompatibility and risk of HNA-3a alloimmunization. The HNA-3 incompatibility in central Thais (33.28%) was higher than northern Thais (28.75%), corresponding to a significantly higher probability of HNA-3a alloimmunization (P<0.05) similar to Japanese and Chinese populations. This study showed the high risk of HNA-3 incompatibility and alloimmunization, especially in central Thai blood donors. A molecular-based identification of the HNA-3 genotype of female donors is suggested to reduce the risk of TRALI following plasma and whole blood allogeneic transfusion.

Non-invasive prenatal diagnosis of fetal RhD by using free fetal DNA

OBJECTIVE

Anti-D immunoglobulin is applied to all pregnant women having RhD incompatibility to prevent hemolytic disease of the newborn. The aim of this study is to determine fetal RhD status in the Rh incompatible pregnancies with an non-invasive technique; free fetal DNA isolation from maternal circulation. In the case of Rh incompatibility especially with a history of previous fetal anemia, it can be beneficial to know Rh status antenatally in terms of monitoring fetuses with Rh positive [RhD(+)] status consciously.

MATERIALS AND METHODS

Total free DNA was isolated in 50 Rh negative [RhD(-)] pregnant women, who had RhD alloimmunisation with their husbands. The gene in isolated DNA was investigated with TagMan prob and real time PCR by using primers belonging to exon 7 of the RhD gene.

RESULTS

The authors analyzed 50 RhD(-) women by using quantitative real time PCR technique. Five of them were RhD(-) and the rest of them were found to be RhD(+). After birth one of the infants who were analyzed as RhD(+) were found to be RhD(-).

CONCLUSION

The detection of fetal RhD status by using a non-invasive method from maternal circulation was found to be possible. Assessing fetal RhD status non-invasively by using free fetal DNA in maternal blood will be cost-efficient, avoiding unnecessary indirect Coombs test and unnecessary Rhogam applications that is used in RH incompatible pregnancies. This study will throw a fresh light on prenatal diagnosis.

Impact of recipient ABH secretor status on outcome in minor ABO-incompatible hematopoietic stem cell transplantation

BACKGROUND

The impact of ABO incompatibility on hematopoietic stem cell transplantation (HSCT) outcome is controversial. As ABH substances are expressed on tissues and secreted in body fluids, they could drive an immune response in minor ABO-incompatible HSCT. The aim of the study was to investigate the prognostic role of the recipients' ABH secretor status.

STUDY DESIGN AND METHODS

Patients who underwent minor ABO-incompatible HSCT were included. Secretor status was determined either serologically or by molecular genetics.

RESULTS

Between March 1996 and June 2012, a total of 176 patients received minor ABO-incompatible HSCT and 150 (85%) were secretors. Incidence and severity of acute graft-versus-host disease (GVHD) and chronic GVHD did not differ between secretors and nonsecretors (cumulative incidences ± standard errors: acute GVHD on Day 100, 41 ± 11 and 46 ± 5%, p = 0.59; chronic GVHD at 2 years, 52 ± 13 and 56 ± 5%, p = 0.62, for secretors and nonsecretors, respectively). Additionally, nonrelapse mortality (NRM) and overall survival (OS) were similar in the two groups (2-year NRM, 27 ± 9 and 23 ± 3%, p = 0.45; 4-year OS, 64 ± 10 and 55 ± 4%, p = 0.28, for secretors and nonsecretors, respectively).

CONCLUSION

The recipients' ABH secretor status in minor ABO-incompatible HSCT has no prognostic impact on major transplant outcomes.

Feline blood genotyping versus phenotyping, and detection of non-AB blood type incompatibilities in UK cats

OBJECTIVES

The aim of this study was to determine the agreement between AB blood phenotyping and genotyping and determine whether non-AB blood type incompatibilities exist in UK cats.

METHODS

Blood samples underwent phenotyping (A, B or AB) using microplate agglutination, and genotyping (AA, Ab or bb) using pyrosequencing of a fragment of the cytidine monophospho-N-acetylneuraminic acid hydroxylase gene. Non-AB blood type incompatibilities were investigated by cross-matching against reference blood of the same phenotype.

RESULTS

Of 112 cats tested, 86 (77%) were blood phenotype A, 19 (17%) type B and 7 (6%) type AB. Genotype and initial phenotype agreed in 96% (107 of 112) of cats, but 5 were discordant; these were all B phenotype with either AA (n=2) or Ab (n=3) genotype. Two of the five cats had repeat blood samples tested: one was reclassified as phenotype A; the other remained phenotype B. Two cats had incompatibilities on minor cross-match, but these were attributed to phenotyping errors.

CLINICAL SIGNIFICANCE

Unknown mutation(s) associated with phenotype B, resulting in false AA or Ab genotyping, were evident in a small number of cases in this study. No conclusive evidence for non-AB blood type incompatibilities was found.

[Time course of morphological changes in humoral renal allograft rejection in ABO incompatibility between donor and recipient]

One hundred and five biopsy specimens taken in different periods after 34 ABO-incompatible mismatched related kidney transplantations were examined to establish the patterns of humoral activity from the morphological changes and expression of C4d deposits in the peritubular capillaries. Severe reversible forms of acute humoral rejection (AHR) (2 patients) and minimal morphological manifestations (13 patients) were observed in the biopsy specimens taken as long as 2 months later in Group 1 (C4d+). In the early period, the minimal manifestations of AHR did not cause organ dysfunction; but in the late period, 5 of them developed chronic humoral rejection in persistent humoral activity; 4 grafts were removed 531,720, 1019, and 1252 days later. Group 2 (C4d-) (n = 19) showed no graft losses or significant chronic changes; the late minimal manifestations of AHR had no impact on the duration of organ function in 3 recipients. The timely detection of early humoral activity and minimal manifestations of AHR is needed for the measures taken to reduce a risk for late function loss of the grafted organ.

[High-throughput genotyping multiplex ligation-dependent probe amplification for assisting diagnosis in a case of anti-Di(a)-induced severe hemolytic disease of the newborn]

OBJECTIVE

To report a rare case of hemolytic disease of the newborn (HDN) with kernicterus caused by anti-Di(a) diagnosed using high-throughput genotyping multiplex ligation-dependent probe amplification (MLPA).

METHODS

Conventional serological methods were used to detect the antibodies related with HDN. The genotypes of more than 40 red blood cell antigens for the newborn and her parents were obtained using the high-throughput MLPA assay. The antibody titers were tested using a standard serological method.

RESULTS

The unknown antibody against the low-frequency antigens was predicted based on the primary serological tests. The genotyping results for more than 40 red blood cell antigens of the newborn and her parents showed incompatible antigens of MNS and Diego blood group system, indicating the existence of anti-N or anti-Di(a). Further serological tests confirmed anti-Di(a) existence in the plasma of the newborn and her mother. The titer of anti-Di(a) in the mother's plasma was 1:32.

CONCLUSION

Severe HDN including kernicterus can result from anti-Di(a). High-throughput genotyping MLPA assay can help type some rare antigens in complicated cases. The reagent red cell panels including Di(a)-positive cells are necessary in routine antibody screening test in Chinese population.

DNA-based methods in the immunohematology reference laboratory

Although hemagglutination serves the immunohematology reference laboratory well, when used alone, it has limited capability to resolve complex problems. This overview discusses how molecular approaches can be used in the immunohematology reference laboratory. In order to apply molecular approaches to immunohematology, knowledge of genes, DNA-based methods, and the molecular bases of blood groups are required. When applied correctly, DNA-based methods can predict blood groups to resolve ABO/Rh discrepancies, identify variant alleles, and screen donors for antigen-negative units. DNA-based testing in immunohematology is a valuable tool used to resolve blood group incompatibilities and to support patients in their transfusion needs.

Possible suppression of fetal erythropoiesis by the Kell blood group antibody anti-Kp(a)

Antibodies to antigens in the Kell blood group system are usually immunoglobulin G, and, notoriously, anti-K, anti-k, and anti-Kp(a) can cause severe hemolytic transfusion reactions, as well as severe hemolytic disease of the fetus and newborn (HDFN). It has been shown that the titer of anti-K does not correlate with the severity of HDFN because, in addition to immune destruction of red blood cells (RBCs), anti-K causes suppression of erythropoiesis in the fetus, which can result in severe anemia. We report a case involving anti-Kp(a) in which one twin was anemic and the other was not. Standard hemagglutination and polymerase chain reaction (PCR)-based tests were used. At delivery, anti-Kp(a) was identified in serum from the mother and twin A, and in the eluate prepared from the baby’s RBCs. PCR-based assays showed twin A (boy) was KEL*841T/C (KEL*03/KEL*04), which is predicted to encode Kp(a+b+). Twin B (girl) was KEL*841C/C (KEL*04/KEL*04), which is predicted to encode Kp(a–b+). We describe the first reported case of probable suppression of erythropoiesis attributable to anti-Kp(a). One twin born to a woman whose serum contained anti-Kp(a) experienced HDFN while the other did not. Based on DNA analysis, the predicted blood type of the affected twin was Kp(a+b+) and that of the unaffected twin was Kp(a–b+). The laboratory findings and clinical course of the affected twin were consistent with suppression of erythropoiesis in addition to immune RBC destruction.

A review of the Chido/Rodgers blood group

The C4 protein plays an important role in maintaining health and, in some situations complicated by poor expression of the C4 protein, may lead to or exacerbate certain diseases. The blood groups Chido and Rodgers are epitopes on the C4 protein, and polymorphisms associated with these epitopes may lead to the formation of antibodies to the Chido or Rodgers antigens in transfused patients. Identification of anti-Ch or anti-Rg is still based on the antibody neutralization with plasma from Ch-positive or Rg-positive individuals and lack of reactivity with qualified Ch-negative or Rg-negative RBCs. These antibodies may be useful in genetic studies of C4 polymorphisms or, in the case of C4-deficient patients, a signal of the potential for serious illnesses. The recognition of the extreme polymorphism of the C4 gene and the gene complex RCCX should lead to more insights in the understanding of disease risk and potential treatment.

Anti-leucocyte antibodies and embryonic mortality in embryo transferred cows

Cows carrying unrelated transferred embryos (ET) produced anti-leucocyte serum antibodies (aLA) more often than cows carrying their own embryos. Cows carrying the ET showed a higher frequency of cytotoxic reactions against leucocytes from 40-60 randomly chosen cows than individuals carrying their own embryos. The percentage of animals with aLA was higher in cows carrying their second or third transferred embryo than in those with their first transferred embryo. There was no change in the frequency of cytotoxic reactions with repeated pregnancies from transferred embryos. There was no difference in the toxicity of aLA in normal pregnant cows and those carrying transferred embryos. Embryonic mortality (EM) of 35, 73 and 88% was noted during pregnancies from the first, second and third successful ET, respectively. Mortality of 48% occurred in the first pregnancy following an unsuccessful ET. Embryonic mortality of 31% occurred in cows simultaneously carrying their own and a transferred embryo. A direct relationship between the presence of aLA and EM in recipients was not proved. Other fertility problems may lead to EM in cows subjected to repeated transfer of foreign embryos.

A simple screening assay for the most common JK*0 alleles revealed compound heterozygosity in Jk(a-b-) probands from Guam

The Jk(a-b-) phenotype results from alterations in the JK gene and is characterized by absence of the RBC urea transporter in the cell membrane. The frequency of Jk(a-b-) varies among populations,but this phenotype is most commonly found in people of Polynesian and Finnish descent. Although rare, Jk(a-b-) individuals present a clinical challenge because anti-Jk3 is produced readily in response to transfusion and pregnancy, and Jk(a-b-) blood is not routinely available. Identification of Jk(a-b-) patients and donors is most often performed serologically. However, ten JK*0 alleles have been identified, and this information can be used in DNA-based typing. We selected five JK*0 alleles that had been encountered by our reference laboratory in two or more samples from unrelated individuals and designed an allele-specific primer PCR assay for use as an initial screening tool. After in-house validation,we tested genomic DNA from a family: a mother and her two sons referred to us for genetic investigation of their Jk(a-b-)phenotypes. Two different nucleotide substitutions, -1g>a in intron 5 (IVS5) and 956C>T in exon 10, originally associated with Polynesian and Indian/African populations respectively, were identified in the family. The mother and one son were compound heterozygotes, and the second son was homozygous for IVS5-1g>a. We conclude that the effort to design and validate such a screening assay was cost-efficient when compared with DNA sequencing costs. Furthermore, selection of the more common JK*0 mutations was a practical approach that resulted in rapid identification of the genetic bases behind the Jk(a-b-) phenotypes in this unusual family. Although an obvious target for eventual inclusion into high-throughput genotyping platforms for clinical diagnostic services, current systems are very limited. Our approach provides a simple and inexpensive method for the identification of these rare alleles.

Distribution of the FYBES and RHCE*ce(733C>G) alleles in an Argentinean population: implications for transfusion medicine

BACKGROUND

The understanding of the molecular bases of blood groups makes possible the identification of red cell antigens and antibodies using molecular approaches, especially when haemagglutination is of limited value. The practical application of DNA typing requires the analysis of the polymorphism and allele distribution of the blood group genes under study since genetic variability was observed among different ethnic groups. Urban populations of Argentina are assumed to have a white Caucasian European genetic component. However, historical and biological data account for the influence of other ethnic groups. In this work we analyse FY and RH blood group alleles attributed to Africans and that could have clinical implications in the immune destruction of erythrocytes.

METHODS

We studied 103 white trios (father, mother and child, 309 samples) from the city of Rosario by allele specific PCRs and serological methods. The data obtained were analysed with the appropriate statistical test considering only fathers and mothers (n = 206).

RESULTS

We found the presence of the FY*BES and RHCE*ce(733C>G) alleles and an elevated frequency (0.0583) for the Dce haplotype. The number of individuals with a concomitant occurrence of both alleles was significantly higher than that expected by chance. We found that 4.68% of the present gene pool is composed by alleles primarily associated with African ancestry and about 10% of the individuals carried at least one RH or FY allele that is predominantly observed among African populations. Thirteen percent of Fy(b-) subjects were FY*A/FY*BES.

CONCLUSION

Taken together, the results suggest that admixture events between African slaves and European immigrants at the beginning of the 20th century made the physical characteristics of black Africans to be invisible nowadays. Considering that it was a recent historical event, the FY*BES and RHCE*ce(733C>G) alleles did not have time to become widespread but remain concentrated within families. These findings have considerable impact for typing and transfusion strategy in our population, increasing the pool of compatible units for Fy(b-) individuals requiring chronic transfusion. Possible difficulties in transfusion therapy and in genotyping could be anticipated and appropriately improved strategies devised, allowing a better management of the alloimmunization in the blood bank.

Blood bank issues associated with red cell exchanges in sickle cell disease

Sickle cell disease (SCD) patients are prone to develop complications that include stroke, acute chest syndrome, and other crises. Some of these complications require chronic transfusion therapy or red cell exchange (RCE), either for therapeutic or prophylactic reasons. Due to a discrepancy of red cell antigens between African Americans and Caucasians (majority blood donors), the incidence of alloantibody formation is very high, which makes it difficult to find compatible red cell units, especially for urgent RCE. Some of the above conditions require immediate oxygen delivery to the tissues. Thus, SCD patients undergoing RCE should receive red blood cells with special attributes that include matching for Rh and Kell blood group antigens; RBCs should be fresh in order to provide (1) immediate oxygen delivery and (2) longer surviving cells to reduce the interval between RCE. Also, these units should be pre-storage leukoreduced to prevent febrile non-hemolytic reactions and screened for sickle cell traits to avoid transfusing red cells containing HbS. This requires a concerted effort between the apheresis unit, the local blood bank, and the central blood supplier.

Anti-KEL7 (anti-Js(b)) alloimmunization diagnostic supported by molecular KEL*6,7 typing in a pregnant woman with previous intrauterine deaths

Anti-KEL7 (anti-Js(b)) is a rare antibody that has been related to haemolytic transfusion reactions and HDN. We report a case of anti-KEL7 alloimmunization detected in a pregnant woman who had an obstetric previous history of four miscarriages and one stillborn. Employing classical immunohematological techniques, we studied the propositus and her available relatives. Due to the unavailability of commercial anti-KEL6 and anti-KEL7 reagents, we used a KEL*6,7 genotyping method as an alternative tool to contribute with the identification of the alloantibody origin. The results of KEL genotyping showed that the propositus was KEL*6/6 homozygous, while her second partner was KEL*7/7 homozygous.

Molecular testing for transfusion medicine

PURPOSE OF REVIEW

Molecular testing methods were introduced to the blood bank and transfusion medicine community more than a decade ago after cloning of the genes made genetic testing for blood groups, that is genotyping, possible. This review summarizes the progress made in the last decade in applying genotyping to prenatal practice and clinical transfusion medicine.

RECENT FINDINGS

Assays that target allelic polymorphisms prevalent in all populations are reproducible and highly correlated with red blood cell phenotype. For some blood groups, assays that detect silencing mutations are also required for accurate typing, and for ABO and Rh, multiple regions of the genes must be sampled. Genotyping is a powerful adjunct to serologic testing and is superior for typing transfused patients, for D-zygosity determination, for noninvasive fetal typing, and for antigen-matching in sickle cell patients.

SUMMARY

Implementation of molecular testing for transfusion medicine has been a conservative process and limited primarily to reference laboratory environments. With the development of high-throughput platforms, genotyping is poised to move into the mainstream, revolutionizing the provision of antigen-negative donor units. This will enable electronic selection of units antigen matched to recipients at multiple blood group loci, potentially eliminating alloimmunization and significantly improving transfusion outcomes.

Xenotransplantation and ABO incompatible transplantation: The similarities they share

Transplantation of kidney allografts across the ABO barrier has been feasible with the development of technologies for removal of anti-blood group antibodies from the circulation of the recipent. The recipients of ABO incompatible grafts display tolerance, accommodation or rejection of the graft. Understanding the factors that determine the outcome of the immune response against incompatible blood group antigens has required the study of an appropriate experimental animal model. The model used is that of knockout (KO) mice for the alpha1,3galactosyltransferase gene, lacking the alpha-gal epitopes and transplanted with wild type mouse heart expressing the alpha-gal epitope. The alpha-gal epitope (Galalpha1-3Galbeta1-(3)4GlcNAc-R) is one of the most abundant carbohydrate epitopes on cells of non-primate mammals and New World monkeys, where it is synthesized by the glycosylation enzyme alpha1,3galactosyltransferase. In humans, apes and Old World monkeys, this epitope is absent due to an evolutionary event that led to the inactivation of the alpha1,3galactosyltransferase gene in ancestral Old World primates. Instead, humans, apes and Old World monkeys produce a natural antibody, the anti-Gal antibody, that is the most abundant natural antibody in humans (approximately 1% of circulating immunoglobulins) and which specifically interacts with alpha-gal epitopes. The interaction between anti-Gal and alpha-gal epitopes is a major immunologic barrier in xenotransplantation, preventing transplantation of pig organs or tissues (i.e. xenografts) into humans. Anti-Gal antibodies also comprise a large proportion of anti-blood group B activity in A and O individuals. Moreover, in recipients of ABO incompatible grafts, much of the elicited anti-A and anti-B antibodies are in fact anti-Gal antibodies capable of binding also to the incompatible blood group antigens. Since the alpha-gal epitope is very similar in its structure to blood groups A and B, understanding anti-Gal response to alpha-gal epitopes is likely to provide information on the immune response to ABO incompatible antigens. Studies on the immune response to alpha-gal epitopes in KO mice have indicated that this epitope can not activate T cells. Anti-Gal B cells engaging alpha-gal epitopes on transplated wild type mouse heart can be activated to produce their antibodies only if they receive help from T cells that are activated by allogeneic or xenogeneic peptides. If T cell help is not available for several days the B cells are induced to differentiate into cells capable of producing accommodating antibodies. Accommodating anti-Gal antibodies bind to the incompatible carbohydrate antigen but do not induce rejection. Prolonged exposure of anti-Gal B cells to the incompatible alpha-gal epitope on the wild type mouse heart graft induces tolerance due to the deletion of these B cells. These studies imply that similar variation in the availability of T cell help in recipients of ABO incompatible grafts result in rejection, accommodation or tolerance, to the blood group antigen. The studies on immune response to incompatible alpha-gal epitopes have further indicated that tolerance to incompatible blood group antigens can be achieved by gene therapy with autologous bone marrow cells or autologous lymphocytes engineered to express the incompatible blood group antigen. Studies in the mouse model suggest that administration into the patient such autologous cells engineered to express the incompatible transplantation carbohydrate antigen induces deletion of anti-blood group B cells and induction of tolerance, provided that the anti-blood group antibodies are removed. Such tolerance is perpetuated indefinitely by the subsequent transplantation of the organ expressing the incompatible blood group antigen.

Tissue distribution of blood group membrane proteins beyond red cells: Evidence from cDNA libraries

The proteins of blood group systems are expressed on red blood cells (RBC) by definition. We searched nucleotide databases of human expressed sequence tags (EST) to collate the distribution of 22 distinct membrane proteins in cells and tissues other than RBC. The documented blood group genes are: MNS, Rh, Lutheran, Kell, Duffy, Kidd, Diego, Yt, Xg, Scianna, Dombrock, Colton, Landsteiner-Wiener, Kx, Gerbich, Cromer, Knops, Indian, Ok, Raph, John-Milton-Hagen and Gill. The genes were grouped according to their overall and their relative expression in embryo and adults. We describe the distribution of EST in cells, tissues and cell lines with a focus on non-RBC tissues.

Incorporating serotypes into family based association studies using the MFG test

Family based association tests are widely used to detect genetic effects. The focus of this paper is the maternal-fetal genotype (MFG) incompatibility test, a family based association test which can be used to detect genetic effects that contribute to disease, including alleles in the child that increase disease risk, maternal alleles that increase disease risk in the child, and maternal-fetal genotype incompatibilities. Consideration of incomplete data resulting from using serotypes could expand the power of the MFG test for detecting genetic effects. Serotypes may be all that are available in certain families, or preferred because of convenience or low cost, and thus a modification of the MFG test will allow optimal use of such data. The modified MFG likelihood can accommodate the incomplete data that result from using serotypes rather than the corresponding codominant genotypes. The modified MFG test was evaluated with serotypes and genotypes from families with members affected with schizophrenia. In addition, simulation studies were performed. Results of the data analyses and simulation studies showed that serotypes can be used to augment genotypes within a sample, to increase power to detect effects when the candidate gene produces serotypes.

Impact of ABO blood groups on the fertility of different parental pairs

Classical works dealing with the possibility of mother-child incompatibility with regard to basic ABO blood groups give contradictory conclusions. Bioreproductive and population-genetic indicators have been studied in a sample of live births and in two pregnancy samples with different "a priori" and "a posteriori" risk assessment. The analysis points out that ABO blood groups can influence fertility of different parental pairs, and consequently--assessment of the individual pregnancy risk.

DR3 is associated with type 1 diabetes and blood group ABO incompatibility

Type 1 diabetes is associated with autoimmunity against pancreatic beta cells. ABO incompatibility is associated with ABO immunization during pregnancy. Type 1 diabetes is associated with certain HLA DR and DQ haplotypes. The mechanism by which blood group incompatibility is associated with the risk of type 1 diabetes is not known. We propose that certain HLA alleles contribute to the development of both type 1 diabetes and ABO blood group incompatibility. We studied 57 children with ABO blood group incompatibility, 118 children with type 1 diabetes, and 98 age- and sex-matched unrelated healthy controls from Linköping. Typing of HLA DQA1, DQB1, and DRB1 was done on DNA extracted from peripheral blood, by PCR amplification, manual dot-blotting onto nylon membranes, synthetic sequence-specific oligonucleotide (SSO) probe 3' end-labeling with 32P-dCTP, and hybridization followed by stringency washes and autoradiography. We observed that DR3 allele was more frequent in patients with ABO incompatibility when compared to healthy controls (OR = 2.7, P(c) < 0.05). Patients with type 1 diabetes had significantly higher frequency of DR3, DQ2, DR4, and DQ8 alleles when compared to healthy controls. No significant difference was observed in frequency of DR3 between ABO blood group incompatibility and type 1 diabetes patients. We conclude that DR3 is associated with both the development of type 1 diabetes and ABO incompatibility.

Maternal-fetal interaction in the ABO system: a comparative analysis of healthy mothers and couples with recurrent spontaneous abortion suggests a protective effect of B incompatibility

We investigated the possible differential effects of A and B blood group materno-fetal incompatibility on human fertility through a comparative analysis of couples with recurrent spontaneous abortion (RSA) and healthy mothers. ABO phenotype was determined in 5180 healthy mothers and their newborn babies from the population of Sassari (Sardinia) and in 1359 healthy puerperae (women who have just given birth) from the population of Rome. Mother-newborn joint ABO distribution in healthy mothers was compared with wife-husband joint ABO distribution in RSA couples. Distortions from expected distribution were evaluated by symmetry analysis. In both RSA couples and healthy mothers significant deviation from expected symmetry patterns were observed. Deviations in RSA are in the opposite direction to those observed in healthy puerperae. The most important difference observed concerned the symmetric joint phenotypes mother (women) A/infant (husband) B (B incompatible) and mother (women) B/infant (husband) A (A incompatible). A low number of B incompatible in RSA couples and a high number of B incompatible in healthy mothers was observed. The phenomenon is much more evident in women aged 24-28 years, a period of maximum fecundity. It is possible that the presence of anti-B immunoglobulin in the mother might have a protective effect against fetal loss in some cases of mother-infant ABO incompatibility.

Neonatal alloimmune neutropenia in premature monozygous twins

Alloimmune neonatal neutropenia (ANN) is an uncommon but potentially life-threatening disorder of the neonate and young infant. Hematologically, the mother's peripheral neutrophil count is normal. However, the passive transfer of maternal immunoglobulin G neutrophil-specific antibodies and the subsequent sensitization of fetal neutrophils can result in severe neutropenia in the neonate. Generally, ANN is a self-limiting condition, but with severe bacterial infection, mortality can be high. We present the clinical features of monozygous twins delivered at 33 weeks' postconception with this condition. This case report is unique in that it occurred in twins born prematurely and was attributable to antibodies against 2 neutrophil-specific antigens, NA1 and NB1. A brief review of the diagnosis, management, and treatment of ANN is presented.

Transfusion-associated graft-versus-host disease with transfusion practice in cardiac surgery

BACKGROUND

Transfusion-associated graft-versus-host disease (TA-GVHD) in immunocompetent patients has still been underdiagnosed and underreported. Risk of TA-GVHD caused by transfusion practice in cardiac surgery should be appropriately recognized.

METHODS

The correlation of TA-GVHD with transfusion practice in cardiac surgery was analyzed from our 17-year clinical experience. We retrospectively reviewed 2,686 consecutive adult patients who underwent cardiac surgery between 1980 and 1996. Classified according to transfusion practice, 847 patients (32%) received nonirradiated fresh homologous whole blood (mean per patient, 5+/-2 units) with or without other blood components; 592 patients (22%) nonirradiated stored RBCs older than 7 days (4+/-2), and 551 patients (21%) received irradiated homologous blood including, fresh whole blood (2+/-1), RBCs (4+/-1), and PCs (8+/-3), respectively. The remaining 696 patients (25%), did not require homologous transfusion.

RESULTS

Four of 847 patients who received nonirradiated fresh homologous whole blood (< or =48 hours after donation) developed TA-GVHD. TA-GVHD did not occur in other patients.

CONCLUSIONS

Our local experience demonstrates the incidence of TA-GVHD in patients who received fresh homologous whole blood in cardiac surgery was much higher, compared with previous reports. This result suggests that the frequency of TA-GVHD is nearly similar to the value calculated from the proportion of HLA haplotypes in the population.

ABO hemolytic disease of the newborn: a unique constellation of findings in siblings and review of protective mechanisms in the fetal-maternal system

Two siblings born 6 years apart presented with similar findings of hepatosplenomegaly, dermal hematopoiesis, hemoglobinuria, and increased platelet consumption, but only moderate anemia and normal serum bilirubin. ABO incompatibility was identified, and other causes were excluded. A review of the current understanding of mechanisms that promote and prevent antibody-mediated hemolysis in the fetus is reviewed. Due to the low ratio of observed to expected significant clinical events among ABO incompatible mother-infant pairs, and the multiplicity of mechanisms that diminish hemolysis, we speculate that severe ABO hemolytic disease of the newborn occurs when there is a specific failure in one of these preventive mechanisms.

NOR polyagglutination and Sta glycophorin in one family: relation of NOR polyagglutination to terminal alpha-galactose residues and abnormal glycolipids

BACKGROUND

This report describes the characterization of polyagglutinable red cells (RBCs), identified in two generations of a Polish family.

CASE REPORT

Untreated and modified RBCs of the proposita (TS) were tested by serologic methods, using human sera, antibodies, lectins, and inhibitors of agglutination. Moreover, glycophorins were characterized by sodium docecyl sulfate-polyacrylamide gel electrophoresis and Western blotting, and glycolipids were purified, fractionated by thin-layer chromatography, and detected with Ricinus communis agglutinin I (RCA-I, specific for galactose residues) and Griffonia simplicifolia IB4 lectin (GSL-IB4, specific for Gal alpha1-3Gal- structure). Some of the experiments were also performed on RBCs of members of TS's family.

RESULTS

Polyagglutination, found in four members of TS's family, was identified as the second case of an earlier described NOR polyagglutination. The polyagglutination was decreased by treating the RBCs with alpha-galactosidase and was inhibited by a neutral glycolipid fraction from NOR+ RBCs. Detection of neutral glycolipids of TS's RBCs on the thin-layer plate by RCA-I and GSL-IB4 revealed the presence of components that were not detectable in control RBCs. Moreover, Western blotting of RBC membranes from five family members with glycophorin monoclonal antibodies and agglutination assays with anti-St(a) and anti-Dantu sera identified the presence of St(a) glycophorin in four members of the family, two of whom were NOR+ and two NOR-.

CONCLUSION

Our results showed that two rare features of TS's RBCs, NOR polyagglutination and St(a) glycophorin, are inherited independently, and that NOR+ RBCs contain neutral glycolipids with an abnormal oligosaccharide structure, most likely terminated with alpha-galactosyl residues.

Prenatal genotyping of the Duffy blood group system by allele-specific polymerase chain reaction

Maternal allo-immunization to antigens of the Duffy blood group system can result in haemolytic disease of the newborn (HDN), therefore, the application of allele-specific polymerase chain reaction (ASPCR) for prenatal genotyping of the Duffy antigen system to identify pregnancies at risk for HDN was evaluated. Oligonucleotide primers were designed for ASPCR of FYA, FYB and nullFY alleles. A validation study was performed using DNA isolated from 94 serotyped whole blood samples and 8 amniocentesis samples. A concordance rate of 100 per cent was observed between serotyping and ASPCR detection of the FYA, FYB and nullFY alleles. This assay is particularly useful for rapid genotyping of fetal amniotic cells to identify pregnancies at risk for HDN due to maternal fetal incompatibilities within the Duffy blood group system.

[Thrombocyte alloantigens]

A variety of alloantigens is expressed by the platelet membrane, whereby currently seventeen platelet specific antigen systems have been recognized. However, in Caucasoids immunization occurs most frequently against only four of these alloantigen systems. Alloimmunization can cause neonatal alloimmune thrombocytopenia, post-transfusion purpura and refractoriness for platelet transfusion. The importance of all alloantigen systems is evidenced by their discovery in association with neonatal alloimmune thrombocytopenia. The genetic polymorphisms of all systems is characterized by a single base mutation which induces a single amino acid substitution. This amino acid change is associated with a change of the tertiary structure of the glycoprotein, which results in high antigeneicity. As the molecular structure of thirteen systems has been elucidated, genotypings can be performed from genomic DNA by simple polymerase chain reactions. Thus, any equipped institution can provide typed donors to meet the clinical demands, without the need for specific antisera.

Tail tip necrosis in two litters of Birman kittens

The development of tail tip necrosis in two litters of Birman kittens from the same queen is described. On the basis of blood group testing of the queen and one of the stud cats, a presumptive diagnosis of neonatal isoerythrolysis involving cold-acting agglutinins was made. It is suggested that on presentation of tail tip necrosis in kittens a diagnosis of neonatal isoerythrolysis or isoagglutination should be considered.

Haemolytic disease of the fetus and newborn due to anti-Fy(a) and the potential clinical value of Duffy genotyping in pregnancies at risk

Haemolytic disease of the newborn (HDN) caused by anti-Fy(a) is uncommon and usually mild. Current guidelines recommend that pregnant women with anti-Fy(a) are monitored less rigorously than those with anti-D, -c or -K. However, in a review of our recent experience of 68 pregnancies where anti-Fy(a) was detected, three were identified where the fetus was severely anaemic; in two cases the fetus received intrauterine transfusions. Our data suggest that pregnancies in which anti-Fy(a) is detected at significant titres (> 64) should be closely monitored in a similar way to pregnancies where other 'significant' antibodies are present. Moreover, in the presence of high or rising antibody titres, if the father is heterozygous and functional assays suggest the antibody is active, then fetal genotyping should be offered to help plan the future management of that pregnancy.

Characterization of a new alloantigen (SH) on the human neutrophil Fc gamma receptor IIIb

Polymorphic structures of the neutrophil Fc gamma receptor IIIb (Fc gamma RIIIb) result in alloantibody formation that causes alloimmune neonatal neutropenia and transfusion reactions. Alloantigens located on Fc gamma RIIIb include the antigens NA1 and NA2. In four cases of alloimmune neonatal neutropenia, granulocyte-specific alloantibodies directed against a thus far unknown antigen were detected by granulocyte agglutination and immunofluorescence tests in the maternal sera. By the use of the monoclonal antibody-specific immobilization of granulocyte antigens (MAIGA) assay, the new antigen, termed SH, was located on the Fc gamma RIIIb. Nucleotide sequence analysis of the Fc gamma RIIIb coding region from a SH(+) individual showed a single-base C-->A mutation at position 266, which results in an Ala78Asp amino acid substitution. A family study confirmed that this nucleotide difference is inherited, and corresponds to the SH phenotype. Serologic typing of 309 randomly selected individuals showed an antigen frequency of 5% in the white population. The same frequency was found by genotyping, for which a technique based on polymerase chain reaction (PCR) using sequence-specific primers (PCR-SSP) was developed. Typing of all SH(+) individuals for NA1 and NA2, and PCR-restriction fragment length polymorphism analysis of the NA-specific PCR products from five SH(+) individuals using the SH-specific endonuclease SfaN 1 showed that SH antigen is very probably the result of an additional mutational event in the NA2 form of the Fc gamma RIIIB gene. Immunochemical studies also demonstrated that the SH determinants reside on the 65- to 80-kD NA2 isoform of the Fc gamma RIIIb. Our findings show the existence of an additional polymorphism of the Fc gamma RIIIb, which can result in alloantibody formation causing alloimmune neonatal neutropenia.

Race-related red cell alloantibody problems

Some years ago differences in red cell blood group phenotypes among individuals of different ethnic backgrounds were of little moment to blood transfusion services. This was because in many instances the ethnic group of the majority of patients closely matched that of the donor pool. The dramatic population movements of the last 20-30 years have changed this situation. Now it is not uncommon for a transfusion service whose donors are primarily European Caucasian in ancestry to be required to supply blood for patients, a substantial proportion of whom are of Black or Oriental extraction. This problem affects the donor service in terms of supply and demand, and both the donor service and hospital transfusion service in terms of antibody identification. In this paper some aspects of this problem are explored and illustrations are given of how knowledge of an antibody-maker's ethnic background can sometimes be used to accelerate identification of an antibody, particularly one directed against a very common antigen. The effects of differences in antigen frequency are also considered in terms of long-term transfusion support of some patients.

[HLA and transfusion]

Using published data, the role of the HLA system for transfusion of cellular blood components is described. Transfusion-associated immunomodulation and the causative role of HLA in other side effects of transfusion therapy are discussed, using review articles and original papers from the German and English literature as sources. The HLA system has important implications for transfusion therapy. Sensibilization of recipients with consecutive formation of HLA antibodies impairs the support of thrombocytopenic patients and may cause febrile transfusion reactions. HLA antibody formation in donors may result in transfusion-induced acute lung injury. The transfusion of viable lymphocytes may cause graft-versus-host disease in immunocompromised recipients or after directed donations from relatives, in rare cases even without these conditions. The clinical implications of transfusion-associated immunomodulation are judged differently.

Obstetric implications of rhesus antigen distribution in Mozambican and Swedish women

AB0 and Rhesus phenotypes were analyzed in 199 Mozambican women and the gene frequencies were calculated. The frequencies of the K and Fya antigens were also investigated. The findings were interpreted against the background of the corresponding phenotype distribution of a Swedish population. D- and Du-positive women amounted to 97.0%, which is significantly more than in Sweden (p < 0.001). Among AB0 groups it was found that blood group 0 is significantly more predominant in Mozambican than in Swedish women (p < 0.001). The reverse is true for blood group A (p < 0.001). Blood group B has a similar prevalence in Mozambican and Swedish women. The obstetric implication of the low prevalence of D-negative women is that the Rhesus alloimmunization problem may be of a much smaller magnitude than would be expected.

A parental combination analysis for ABO-HP interaction in a Bengali population

Blood samples from 577 couples and their 657 offspring of Bengali caste group derivation were used to study interactions between ABO blood groups and haptoglobin (HP) systems. There was no significant sex difference in HP distribution among the parents. Significantly higher incidences of HP*1 allele were noted in the offspring of ABO-incompatible parental combinations in comparison with those in the offspring of ABO-compatible parents.

Frequency and inheritance of A and B blood types in feline breeds of the United States

Using a simple hemagglutination assay to determine A and B blood types, we surveyed 1,072 domestic short- and longhair (DSH/DLH) cats and 1,100 purebred cats in the United States. Data from 234 matings with 552 offspring were consistent with the hypothesis that feline blood types A and B are due to the action of two different alleles at the same gene locus and that A is completely dominant over B. Neither an AB nor an O type cat was encountered. No type B cats were found in the Siamese and related breeds or in American Shorthair and Norwegian Forest cats. Among the breeds with type B blood, the proportion was lowest in DSH/DLH cats (0.0028) and variably higher in Abyssinian, Birman, British Shorthair, Devon Rex, Himalayan, Persian, Scottish Fold, and Somali, ranging from 0.15 to 0.59. Since all type B cats have strong, naturally occurring anti-A alloantibodies, fatal neonatal isoerythrolyses occur in type A offspring of type B mothers bred to type A males. The gene frequency of the B allele and the proportion of mating at risk of neonatal isoerythrolysis were estimated in a number of breeds. In most breeds, the frequency of the B allele was less than 0.5. Since the kittens at risk for neonatal isoerythrolysis always have the genotype AB, there is constant natural selection against heterozygotes. Heterozygote disadvantage in the cat AB system represents an unusual form of negative selection, similar to that in Rh blood group incompatibility in humans.

Blood transfusion in the para-Bombay phenotype

The H-deficient phenotypes found in Chinese so far, have all been secretors of soluble blood group substances in saliva. The corresponding isoagglutinin activity (e.g. anti-B in OB(Hm) persons) has been found to be weak in all cases. To determine the clinical significance of these weak isoagglutinins 51Cr red cell survival tests were performed on three OB(Hm) individuals transfused with small volumes (4 ml) of groups B and O RBC. Rapid destruction of most of the RBC occurred whether or not the isoagglutinins of the OB(Hm) individuals were indirect antiglobulin test (IAGT) reactive. When a larger volume (54 ml packed RBC) of group B cells (weakly incompatible by IAGT) was transfused to another OB(Hm) individual with IAGT active anti-HI, the survival of the transfused RBC was 93% at 24 h, with 30% of the RBC remaining in the circulation at 28 d in contrast to 76% as would be expected if the survival was normal. Therefore when whole units of blood of normal ABO blood groups, compatible by IAGT, are transfused, the survival is expected to be almost normal. These weak isoagglutinins may not be very clinically significant and we suggest that when para-Bombay blood is not available, the compatibility testing for OA(Hm) persons should be performed with group A and group O packed RBC; OB(Hm) with group B and group O packed RBC: OAB(Hm) with groups A, B, AB and O packed RBC. For cross matching, the indirect antiglobulin test by a prewarmed technique should be used.

ABO-incompatible living related donor kidney transplantation: report of two cases

The courses of two recipients of ABO-incompatible HLA-identical living related donor kidney transplants are described, the first an A into O and the second a B into A. Both patients were prepared by a month of preoperative azathioprine and a week of plasmapheresis to reduce isohemagglutinin titers in one to 1:2 and in the other to 0 at the time of transplant. Both had early mild steroid-reversible rejections, and the first patient has had an uneventful subsequent course 20 months postgrafting on low-dose cyclosporine and prednisone. The second patient developed a further immunologic event at 1 month that may have been isohemagglutinin mediated or may have been rejection but subsided with OKT3 therapy and plasmapheresis. She lost her graft at 5 months despite normal function during attempts to repair a ureteric fibrosis. Neither patient had donor-specific transfusion or splenectomy. This approach is feasible and should be considered for those patients having related but ABO-incompatible donors.

Febrile transfusion reaction caused by AB0-incompatible platelet transfusion

A febrile transfusion reaction caused by strong isoagglutinins in the patients serum is reported. The reaction resulted from a transfusion of group A platelets in a group 0 patient; the recipients' serum contained high titered isohemagglutinin (Anti-A 1:8192) capable of lysing bloodgroup A1 red cells up to a titer of 1:8. Moreover, the serum showed a strong positive thrombocytotoxic reaction with the platelets of the donor and some other group A individuals, but remained negative with group 0, and turned to negative reaction with group A samples after neutralization with bloodgroup substance. We conclude that pretransfusion testing of group 0 donors and recipients for isohemolysins combined with platelet crossmatching may prevent febrile reactions.

[Status of Kell incompatibility in a 15-year retrospective study of mother-child serology in clinical records]

The frequency and clinical relevance of anti-Kell antibodies is reported based upon 80,509 antibody screenings in pregnant women over a period of 15 years. The pedigrees of two families involved in Kell-incompatibilities illustrate the sometimes tragic outcome of these pregnancies. Seven Kell-incompatibilities in the course of 134 pregnancies in 43 women with anti-Kell antibodies have been serologically verified. Three led to stillbirths, one to neurologic defects, another to jaundice without permanent clinical consequences and two babies had to undergo exchange transfusions but are healthy today. The Kell-selected transfusion strategy practised in our center was derived from our observations on the mode of sensitization. Protection against Kell-sensitization in cases of ABO-incompatible mother-child constellations, as well as possible protective effects of Rh-prophylaxis are discussed. Failure to recognize the problem or delay in serologic diagnosis are the most serious problems facing the Kell-incompatible pregnancy.

[Immunization against the ZWa (PLA1) platelet antigen: group at risk, prevention of complications. Apropos of 132 cases]

The identification of anti-ZWa (-PLA1) alloimmunisation is not very frequent. It can be observed in most perinatal alloimmune thrombocytopenias (PAT) and rare post transfusional purpuras (PTP). On the other hand, the clinical consequences of these immunisations are often dramatic, particularly for the foetuses for which there has been no prevention so far. The retrospective study of 132 cases, 123 PAT and 9 PTP, shows the possible irreversible complications for 18% of the newborns with PAT, but especially for 10% of the foetuses which will show PAT at birth. HLA markers are very useful to detect the people who are likely to develop an anti-PLA1 immunization for they are PLA1 negative and HLA DR3. Then, it becomes possible to prevent the complications of these immunisations. It is what we tried to do through the diagnosis and the treatment of PAT in 3 foetuses.

Anti-EnaFS detected in the serum of an MiVII homozygote

Anti-EnaFS was detected in the serum of a Caucasian woman, K.T., during her third pregnancy. She had not been transfused. At delivery, the infant's red cells (RBCs) had a negative direct antiglobulin test. The antibody was inhibited by isolated MN sialoglycoprotein (SGP). Unlike other En(a-) cells, K.T.'s EnaFS-negative RBCs were found to demonstrate normal sialic acid levels, and an MN SGP exhibiting normal sodium dodecylsulphate electrophoretic mobility and periodic acid-Schiff staining intensity. K.T., whose parents were consanguineous, appears to be the first known MiVII homozygote. In a three-generation family study, MiVII was shown to travel with MS. The Anek receptor of K.T.'s RBCs was found to be located on the trypsin-resistant and V8 protease-sensitive portion of the MN SGP (residues 40 to 57), whereas the Anek receptor of MiVI RBCs was shown to be associated with their abnormal Ss SGP. K.T.'s MN SGP appears to exhibit an amino acid sequence alteration in the region of the EnaFS determinant, which is located within the residues 46 to 56 of the normal MN SGP. These findings suggest that the MiVII and EnaFS receptors are the products of allelic genes.

Clinically significant allo-anti-I in an I-negative patient with massive hemorrhage

A 37-year-old white man who had never been transfused was admitted as an emergency patient with a ruptured spleen and a falling hematocrit (19% on admission). All crossmatches were incompatible. His serum contained anti-I, and his red cells (RBCs) were I-negative and strongly i-positive. Only 4 units of crossmatch-compatible I-negative frozen RBCs were available immediately. Because of the likelihood that more than 4 units would be required, chromium survival studies were performed using I-positive cells. Samples obtained at 15 and 30 minutes after injection revealed less than 1 percent survival of the donor RBCs. He received the 4 units of I-negative RBCs during the operation in addition to reinfusion of RBCs harvested from 1800 ml of blood aspirated from the abdominal cavity. The postoperative hematocrit remained greater than 30 percent and the bilirubin less than 1.5 mg per dl. Before recommending frozen storage of autologous RBCs, 51Cr labeled I-positive RBCs from the patient's daughter (obligate li heterozygote) were infused. Survival was 100 percent at 15 and 30 minutes, 90 percent at 3 hours, 85 percent at 26 hours; the remaining RBCs disappeared at a normal rate (T 1/2 27 days) over the succeeding 2 weeks. A repeat 51Cr-labeled RBC study with the original I-positive donor confirmed greater than 92 percent destruction in 90 minutes. The clinical significance of this allo-anti-l (apparently primarily against RBCs from homozygous I-positive donors) is in marked contrast to reported findings with auto-anti-l antibodies.

AB0 blood group incompatibility and inbreeding effects: evidence for an interaction

It is known that consanguinity reduces the chances of maternal-foetal incompatibility but it is not known whether inbreeding influences the expression of the effects of such incompatibility. This paper investigates and finds evidence for an interaction between inbreeding and AB0 blood group incompatibility on the expression of neonatal mortality, sibship precocious mortality, neonatal jaundice, asphyxia, and sex ratio, through screening of 3923 consecutive newborns. Inbreeding and incompatibility individually showed variable effects on the above parameters, but their interaction was such that, in the presence of inbreeding, incompatibility reduced the incidence/relative risk of all the above factors. Such a uniform negative interaction was presumed to be due to homozygosity of some pleiotropic genes caused by inbreeding.