Résumé
【Objective】 To evaluate the application of monoclonal typing reagents and human anti-A/B antibodies for absorption-elution test in ABO grouping. 【Methods】 The specificity of monoclonal typing reagents and human anti-A/B antibodies with standard A, B, O and AB phenotypes at 4 ℃, room temperature, and 37 ℃ were compared. Affinity was evaluated by the titer, agglutination time and agglutination intensity of the reaction with A1/B cells. 29 samples with ABO discrepancy were tested to evaluate the ability of monoclonal typing reagents and human anti-A/B antibodies to detect weak antigens in absorption-elution test. 【Results】 The specificity and affinity of human anti-A/B antibodies are low, and monoclonal typing reagents have cross reactivity. Human anti-A/B antibodies can detect most weak antigens in absorption-elution test with no cross reactivity. 【Conclusion】 In ABO grouping, the human anti A/B antibody binding absorption-elution test can serve as a supplement method for identifying ABO weak antigens. Accurate results can be obtained with reasonable reagents and corresponding methodology in serological tests,thus ensuring the safety of blood transfusion.
Résumé
BACKGROUND:During the research of ABO blood type antigen, the overwhelming majority samples of same ABO gene express a normal and same ABH antigen. But a certain amount samples with the same ABO genetic background show different antigen intensity expression as for different family or individuals. The ABO blood type has complex expression regulation mechanism. Analysis of ABO blood group serology and genetic background of these rare bi-specific AB phenotype specimens, and further studying on epigenetics may partly revealed ABO gene expression mechanism. OBJECTIVE:To study methylation of CpG island and explore the relationship between ABO gene promoter coding glycosyltransferase with dual donor specificity and ABH antigen expression. METHODS:Six samples detected as CisAB or B(A) phenotype were studied in this paper. The whole code sequences and promoter sequence of ABO gene were amplified respectively. The level of CpG methylation in promoter of ABO gene was further detected with bisulfite treatment method. RESULTS AND CONCLUSION:Among the six bi-specific AB phenotype samples, two previously-identified CisAB05/B(A)06 al eles with nt803C>G on the basis of B101 al ele sequence could be seen, and three additional methylated sites nt-33(30%), nt+27(50%) and nt+49(50%) were found between the two regions of CpG island in promoter of ABO gene. Two CisAB01 al eles with nt803C>G mutation on the basis of A101 sequence were found at nt-26C(10%). Other two B(A)04 al eles contained nt640A>G mutation on the basis of B101 sequence were found in the whole code sequences regions, and six additional methylated sites nt-33(10%), nt+16(50%), nt+57(60%), nt+59(60%), nt+68(60%) and nt+74(60%) were found between the two samples. No abnormity was identified in the promoter region of ABO gene. Our results indicated that the differential methylation levels in the CpG island of ABO gene promoter region may affect ABH antigens expression on the red cel membrane even if the samples had the same ABO genetic background.
Résumé
Human identification is a mainstay of civilization and identification of unknown individuals has always been of paramount importance to society. Establishing individuality is an imperative aspect in any investigating procedure. The use of biological evidence for identification of an individual is a relatively recent development, but it is expensive and time consuming. The Forensic importance of dental tissue has been well recognized because of the fact that tooth is hardest of all human tissues and they can be preserved intact for a long period of time after death. Blood group has been one of the corner stones for identification of biological materials in Forensic investigations, and ABO blood grouping is widely used in Forensic laboratories. In this study an attempt is made to determine ABO blood group from the dental pulp and the dentin extracted from dead body by absorption –elution method.