Composition of erythrocytic (ABO, Rh-Hr, Kell, MN) group antigens characteristic of the Ozurgeti district's population

Erythrocytic group antigens represent a genetically stably determined trait. Investigation of antigens of the said system in different regions is of the greatest importance in terms of both the creation of demographic data of the region as well as practical medicine, especially for transplantology and transfusiology. The peripheral or venous blood of 232 local natives (healthy donors) of Ozurgeti district of Guria region has been taken as the test subject. The test subject was taken by random methods in different vilifies (Bakhvi, Mshvidobauri, Ozurgeti, Likhauri, Gurianta, Bokhvauri, Dvadzu, Pampaleti) To identify the ABO, Rh-Hr, Kell, MN system antigens, an express-method using monoclonal antibodies has been applied. In studying the ABO system, it was fixed that the highest distribution frequency was characteristic of the 0(I) group (52.3±3.2%), then follows the group A(II) (38.5±3.2%). The distribution frequency of the B(III) group is (8.2±1.8%) and that of AB(IV)--(0.8±0.5). The population's 85.2±2.32% is the carrier of the Rh+ phenotypic group, while 14.7±2.3% belongs to the Rh-phenotypic group. In studying the concentration of alleles, the low concentration of p(K) allele was detected that equaled 0.2; the concentration of q(K) allele made 0.8, that of p(M)--0.65, and that of q (N) - 035.

Absence of hemolytic disease of fetus and newborn despite maternal high-titer IgG anti-Ku

Anti-Ku seen in K(o) (Kell-null) individuals has previously been shown to cause severe hemolytic transfusion reactions. Maternal anti-Ku can cause none or moderate to severe hemolytic disease of the fetus and newborn (HDFN). In two of four previously described HDFN cases, intrauterine transfusions were required because of severe anemia. We report a case in which maternal anti-Ku did not cause HDFN. Standard serologic methods were used for RBC antibody screening and identification, adsorption and elution of RBC antibodies, and antigen typing. A gravida 3, para 3 (G3P3) woman was first evaluated in 2006 and was found to have an IgG RBC antibody that reacted against all panel RBCs in the anti-human globulin phase. A panel of RBCs treated with DTT did not react with the antibody. The antibody failed to react with one example of K(o) RBCs. The patient’s RBCs typed negative for the following Kell blood group antigens: KEL1, KEL2, KEL3, KEL4, KEL6, KEL7, KEL11, KEL13, and KEL18. These results established the presence of anti-Ku in maternal serum. The newborn was group A, D+ and required phototherapy for hyperbilirubinemia, but did not require transfusion. The woman was seen again in January 2010 during the third trimester (G4P3). At this time, anti-Ku titer was 256. She delivered a healthy group O, D+ baby boy at 37 weeks' gestation. Cord RBCs were 4+ for IgG by DAT. An eluate reacted with all RBCs tested, but did not react when tested against a panel of DTT-treated RBCs. K(o) phenotype is rare to begin with, and the maternal anti-Ku formation may require more than one pregnancy. Therefore, cases that can be evaluated for anti-Ku–related HDFN are rare. Our case contributes to serologic and clinical aspects of such rare cases.

Optimal blood grouping and antibody screening for safe transfusion

(Full text is available at http://www.manu.edu.mk/prilozi). Introduction. Blood group antigens as integrated parts of the red cell membrane have many essential functions for the cell as well as for the organism, but they are recognized as unique antigens for the purpose of safe blood transfusion. Especially in the case of those with great clinical importance because of their involvement in haemolytic transfusion reactions and hemolytic disease of the newborn, it is very important that they be correctly, and some of them routinely, typed in blood donors as well as in patients. Aim. Evaluation of Rh and Kell blood group antigen frequencies in blood donors as well as the incidence of alloimmunization in transfused patients in the Macedonian population. The need for routine typing of certain blood group antigens in addition to ABO and RhD was also evaluated. Material and method. We evaluated data from 1600 ABO/Rh and Kell typed blood donors (from January 2003 to May 2008), as well as the data from pretransfusion testing (ABO/RhD blood typing, irregular red blood cell antibody screening and compatibility testing) and antibody identification in the period from January 2005 to November 2008. All tests were performed by the DiaMed micro tube gel system. Results. The frequencies of ABO antigens were as follows: A (39.7%), O (38%), B (14.1%), AB (7.4%). The frequencies of Rh antigens were as follows: D pos. (84.2%), D neg. (15.8%), C (58.3%), c (82.4%), E (21.3%), e (97.1%). We found the following frequencies of Kell phenotypes: K+ k- (0.25%), K+ k+ (6.18%), and K- k+ (93.6%) with the total frequency of K antigen of 6.4%. Antibody screening and/or cross-match were positive in the sera from 150 transfused patients. In 75 (50%) sera the following 81 antibodies were identified: anti-K (26), -E (25), -e (1), -C (4), -c (6), -C(w) (2), -k (1), -Fy (a) (3), -Fy(b) (1), -Jk(a) (3), -Lu(b) (1), -Le(b) (2), -Le(a) (1), -M (4), -P1 (1). The most frequent alloantibody was anti-K with 32%, and anti-E with 30.8% of all identified antibodies. Conclusion. Alloimmunization to red cell antigens is still a current problem in our transfusion practice. It is obvious that the additional testing of blood donors for Rh and Kell antigens should be implemented as a routine to prevent as far as possible the incidence of alloimmunization. It would also be cost-effective, bearing in mind the additional laboratory testing necessary to provide compatible blood for alloimmunized patients. Extended blood typing should be implemented for some categories of polytransfused patients as well. This strategy is another step forward to improve the safety of blood transfusion with optimal blood grouping. Key words: Kell phenotypes frequency, alloimmunization, blood grouping, safe transfusion.

Molecular genetic blood group typing by the use of PCR-SSP technique

BACKGROUND

DNA-based methods are useful for enhancing immunohematology typings. Ready-to-use Conformité Européenne (CE)-marked test kits based on polymerase chain reaction with sequence-specific priming (PCR-SSP) have been developed, which enable the examination of weak, unexpected, or unclear serologic findings. DEVELOPMENT AND VALIDATION: Primers were designed according to established mutation databases. Proficiency testing for CE marking was performed in accordance with Directive 98/79EC of the European Parliament and of the Council of October 27, 1998 on in vitro diagnostic medical devices using pretyped in-house and external samples. INTENDED USE: BAGene PCR-SSP kits are in vitro diagnostic devices. Genotyping of ABO and RHD/RHCE as well as HPA and KEL, JK, and FY specificities has to be performed after the conclusion of the serologic determination.

APPLICATION

Ready-to-use PCR-SSP typing kits allow the determination of common, rare, or weak alleles of the ABO blood group, Rhesus, and Kell/Kidd/Duffy systems as well as alleles of the human platelet antigens.

RESULTS

The investigations showed clear-cut results in accordance with serology or molecular genetic pretyping.

CONCLUSION

PCR-SSP is a helpful supplementary technique for resolving most of the common problems caused by discrepant or doubtful serologic results, and it is an easy-to-handle robust method. Questionable cases in donor, recipient, and patient typing can be examined with acceptable cost.

Management of Kell isoimmunization--evaluation of a Doppler-guided approach

OBJECTIVE

To assess the role of peak systolic velocity in the middle cerebral artery (MCA-PSV) in the management of pregnancies complicated by Kell isoimmunization.

METHODS

Sixteen fetuses were monitored by conventional protocol (Group 1) and eight fetuses by an MCA-PSV-guided protocol (Group 2). The conventional protocol included a weekly ultrasound evaluation and measurement of maternal anti-Kell titers every 4-6 weeks. In Group 2 Doppler assessment of the MCA-PSV was performed at intervals of 4 to 7 days and MCA-PSV>1.5 multiples of the median (MoM) was considered as an indication for fetal blood sampling (FBS).

RESULTS

No parameter emerged as a reliable predictor of isoimmunization severity in Group 1. In Group 2, no FBS was necessary in one case since the MCA-PSV values obtained during the follow-up were <1.29 MoM. In two cases the first FBS was already indicated after 1 week of follow-up, but five other fetuses were followed for 3-9 weeks before FBS was indicated. All fetuses with MCA-PSV>1.5 MoM prior to intrauterine transfusion (IUT) had severe fetal anemia on FBS. In fetuses with severe anemia on the first FBS, the MCA-PSV values 7 days before the first FBS were <1.29 MoM (four cases), between 1.29 and 1.5 MoM (two cases) and >1.55 MoM (one case).

CONCLUSIONS

In the management of Kell isoimmunization invasive procedures may be avoided by implementing MCA-PSV measurements. Delineation of appropriate intervals between reassessments, the reliability of MCA-PSV following repeated IUTs, and cut-off values for FBS await further study.

K, Fy(a), and Jk(a) phenotyping of donor RBCs on microplates

BACKGROUND

In many cases, the search for compatible blood for patients with clinically significant RBC alloantibodies is difficult and time-consuming. To date, it has been considered necessary only to phenotype the blood donors for ABO group and D. There has been long experience with automated routine analysis (ABO, C, c, D, E, and e typing and RBC antibody screening), using robotic dispensers and computerized interpretation of microplate results. The purpose of this study was to explore the possibilities of also phenotyping for K, Fy(a), and Jk(a), as antibodies directed against these antigens (together with Rh antigens) are the most common clinically significant alloantibodies in the Swedish population.

STUDY DESIGN AND METHODS

One thousand thirty-one EDTA samples from blood donors were phenotyped for K, Fy(a), and Jk(a) by use of an IAT with PEG on microplates. The findings were compared to those using conventional IAT in tube's and the microcolumn gel test (DiaMed-ID, DiaMed).

RESULTS

All typing results with the microplate method were correct. All reactions for K and Fy(a) typing could be interpreted by the computer. The results for Jk(a) were indeterminate in 1.4 percent (14/1031) of the samples.

CONCLUSION

The PEG-IAT microplate method gave reliable results that were suitable for routine phenotyping, thus making available a stock of phenotyped blood at reasonable cost, ready for delivery when required.

Antenatal genotyping of the blood groups of the fetus

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.

Detection of Kell blood groups: molecular methods in the diagnostic laboratory

The introduction of molecular biology techniques to the field of transfusion medicine has allowed more detailed analysis of the basis for the expression of several blood-group antigens. The application of the polymerase chain reaction for the determination of red-cell blood-group genotype is a highly sensitive technique that can be used to determine the likelihood of a fetus being affected by haemolytic disease of the fetuses or newborn. This alone makes polymerase chain reaction based techniques highly desirable for such applications. The determination of the genetic basis for the Kell/Cellano polymorphism has enabled the development of polymerase chain reaction-based techniques for genotyping. Several other red-cell blood-group antigen polymorphisms can also be analysed in this way.

Rapid detection of Rh(D)- or K-positive fetal red cells in chorion villus samples by a flow cytometric technique

Rh(D)- and K-negative women who have become severely isoimmunized by pregnancy are at risk of fetal loss or damage in subsequent pregnancies. A flow cytometric method is described whereby the presence of Rh(D) or K antigen on fetal erythrocytes may be determined using chorion villus samples taken during the first trimester. This method has the advantage of speed and sensitivity with results being available within 2 h. Decisions as to management of the pregnancy or termination may thus be made with minimal delay.

Application of the MAIEA assay to the Kell blood group system

The monoclonal antibody-specific immobilisation of erythrocyte antigens (MAIEA) test has been employed to investigate the Kell system using five monoclonal antibodies which recognise high frequency epitopes on the 93,000-molecular weight Kell glycoprotein: BRIC 18, BRIC 68, BRIC 107, BRIC 203 and 6-22. BRIC 107, which has anti-k-like (KEL2) specificity, identifies a distinct epitope, whilst competitive binding assays suggested that BRIC 203 (anti-Kpbc), BRIC 18, BRIC 68 and 6-22 (anti K14) comprise an overlapping set of epitopes. The MAIEA assay has been very successful in confirming the assignment of most of the Kell and para-Kell antigens to the Kell protein. Due to the competitive nature of the assay and the fact that the monoclonal antibodies bind to different regions, the results also suggest the relative positions of some of the Kell antigens on the Kell protein; these appear to be located in at least five spatially distinct regions.

Characterization of the blood group Kell (K1) antigen with a human monoclonal antibody

A human monoclonal anti-Kell (K1) antibody secreted by an Epstein-Barr virus (EBV)-transformed B-cell line was used for binding studies and immunopurification of the K1 blood group antigen. The 125I-labeled antibody bound to 4 to 5 x 10(3) and 2.5 to 3 x 10(3) antigenic sites on K1K1 and K1K2 erythrocytes, respectively, with an affinity constant of 5 x 10(8) mol/L-1. Immunoprecipitation analysis showed that the K1 antigen is carried by a 93 Kd glycoprotein containing several cysteine residues, and approximately six N-glycosidically linked sugar chains but no detectable O-linked sugar. A minor labeled component of 32 Kd was also immunoprecipitated from K1K1 RBCs but the 93- and 32-Kd components were absent from K2K2 and Kell null erythrocytes. Under nonreducing conditions, three bands were detected at 200 (weak), 120, and 93 Kd. We suggest that the 120-Kd component represents a heterodimer of the 93- and 32-Kd proteins covalently linked by disulfide bridge(s). The 93-Kd glycoprotein is a transmembrane component which interacts with the membrane skeleton but is distinct from band 3 as shown by one-dimensional peptide mapping. The site density of K1 antigen blood group on Gerbich-negative RBCs (Ge:-2,-3) was threefold lower than on K1K1 erythrocytes, but the qualitative properties of the 93-Kd component were not modified.