Single­strained DNA aptamers mask RhD antigenic epitopes on human RhD+ red blood cells to escape alloanti­RhD immunological recognition.

Rhesus D­ (RhD­) individuals should receive Rh­matched blood to prevent hemolytic anemia. However, there is a shortage of RhD­ blood. This study aimed to generate RhD antigen­specific single­stranded DNA (ssDNA) aptamers, and test their efficacy in masking RhD antigens on RhD+ red blood cells (RBCs) to prevent their immunoreactivity in vitro. In the present study, ssDNA aptamer candidates were synthesized as a central randomized sequence of 40 nucleotides (nt) flanked by 21­nt primer hybridization sequences. The functional aptamers were screened using the cell­based systematic evolution of ligands by exponential enrichment technique and RhD+ RBCs. Two bioactive ssDNA aptamers significantly inhibited the binding of an anti­RhD antibody to RhD+ RBCs and bound to RhD antigens with high affinity (dissociation constant values of 580.5±142.0 and 737.7±161.8 nM, respectively). Furthermore, treatment with both ssDNA aptamers (500 pmol) effectively masked RhD antigens on 4,000,000 RhD+ RBCs to prevent human anti­RhD alloantibody­mediated binding, RBC agglutination and monocyte recognition in vitro. Collectively, such data suggested that these ssDNA aptamers may be feasible for masking RhD antigens on RBCs, and thus valuable for prevention or at least amelioration of RhD+­related hemolytic anemia in RhD­ individuals.

Autoantibody-Mediated Erythrophagocytosis Increases Tuberculosis Susceptibility in HIV Patients.

Macrophage dysfunction is associated with increased tuberculosis (TB) susceptibility in patients with human immunodeficiency virus (HIV) infection. However, the mechanisms underlying how HIV infection impairs macrophage function are unclear. Here, we found that levels of autoantibodies against red blood cells (RBCs) were significantly elevated in patients with HIV as determined by direct antiglobulin test (DAT). DAT positivity was significantly associated with TB incidence in both univariate and multivariate analyses (odds ratio [OR] = 11.96 [confidence interval {CI}, 4.68 to 30.93] and 12.65 [3.33 to 52.75], respectively). Ex vivo analysis showed that autoantibodies against RBCs enhanced erythrophagocytosis and thus significantly impaired macrophage bactericidal function against intracellular Mycobacterium tuberculosis Mechanistically, autoantibody-mediated erythrophagocytosis increased heme oxygenase-1 (HO-1) expression, which inhibited M. tuberculosis-induced autophagy in macrophages. Silencing ATG5, a key component for autophagy, completely abrogated the effect of erythrophagocytosis on macrophage bactericidal activity against M. tuberculosis In conclusion, we have demonstrated that HIV infection increases autoantibody-mediated erythrophagocytosis. This process impairs macrophage bactericidal activity against M. tuberculosis by inhibiting HO-1-associated autophagy. These findings reveal a novel mechanism as to how HIV infection increases TB susceptibility.IMPORTANCE HIV infection significantly increases TB susceptibility due to CD4 T-cell loss and macrophage dysfunction. Although it is relatively clear that CD4 T-cell loss represents a direct effect of HIV infection, the mechanism underlying how HIV infection dampens macrophage function is unknown. Here, we show that HIV infection enhances autoantibody-mediated erythrophagocytosis, which dampens macrophage bactericidal activity against TB by inhibiting HO-1-associated autophagy. Our findings reveal a novel mechanism explaining how HIV infection increases susceptibility to TB. We propose that DAT could be a potential measure to identify HIV patients who are at high TB risk and who would be suitable for anti-TB chemotherapy preventive treatment.

Single-stranded DNA aptamer targeting and neutralization of anti-D alloantibody: a potential therapeutic strategy for haemolytic diseases caused by Rhesus alloantibody.

BACKGROUND: Rhesus (Rh) D antigen is the most important antigen in the Rh blood group system because of its strong immunogenicity. When RhD-negative individuals are exposed to RhD-positive blood, they may produce anti-D alloantibody, potentially resulting in delayed haemolytic transfusion reactions and Rh haemolytic disease of the foetus and newborn, which are difficult to treat. Inhibition of the binding of anti-D antibody with RhD antigens on the surface of red blood cells may effectively prevent immune haemolytic diseases. MATERIALS AND METHODS: In this study, single-stranded (ss) DNA aptamers, specifically binding to anti-D antibodies, were selected via systematic evolution of ligands by exponential enrichment (SELEX) technology. After 14 rounds of selection, the purified ssDNA was sequenced using a Personal Genome Machine system. Haemagglutination inhibition assays were performed to screen aptamers for biological activity in terms of blocking antigen-antibody reactions: the affinity and specificity of the aptamers were also determined. RESULTS: In addition to high specificity, the aptamers which were selected showed high affinity for anti-D antibodies with dissociation constant (Kd) values ranging from 51.46±14.90 to 543.30±92.59 nM. By the combined use of specific ssDNA aptamer 7 and auxiliary ssDNA aptamer 2, anti-D could be effectively neutralised at low concentrations of the aptamers. DISCUSSION: Our results demonstrate that ssDNA aptamers may be a novel, promising strategy for the treatment of delayed haemolytic transfusion reactions and Rh haemolytic disease of the foetus and newborn.

[Establishment and Application of a Method for Determination of Glycosyltransferase Activity].

OBJECTIVE: To establish a method for determination of glycosyltransferase and to explore the enzyme A, B glycosyltransferase activity in human serum so as to lay the foundation for the determination of enzyme level and enzyme activity. METHODS: The glycosyltransferase activity kit was used to draw phosphate standard curves in our laboratory. The A and B glycosyltransferase activity were determined by the standard curves. RESULTS: The standard curves (y=2671.3x-0.596 R2=0.9998) for determing glycosyltransferase activity suitable for use in our laboratory were drawn. At the same time the method was set up for determination of A, B glycosyltransferase in human serum. CONCLUSION: The establised method of the determination of glycosyltransferase is suitable for common type of enzyme activity and suitable for the A, B glycosyltransferase in human serum.

Intron 4 of the RH Gene in Han Chinese, Tibetan, and Mongol Populations.

AIMS: This study aimed to compare the intron 4 sequence of the RHD and RHCE genes from Han Chinese, Tibetans, and Mongols, and explore its polymorphisms. MATERIALS AND METHODS: To investigate the distinction in the RHD and RHCE intron 4, polymerase chain reaction (PCR) was performed by a set of primers: Intron4F and Intron4R. Primer Intron4F for a sequence located in exon 4 and primer Intron4R for a sequence located in exon 5, respectively. RHD and RHCE intron 4 of all the samples from 26 cases of random unrelated Hans (13 RhD-positive donors and 13 RhD-negative donors), 25 cases of random unrelated Tibetans (18 RhD-positive donors and 7 RhD-negative donors), and 4 cases of random unrelated Mongols (1 RhD-positive donor and 3 RhD-negative donors) were amplified with PCR. The PCR products were then sequenced. RESULTS: A 576-bp product was detected in all the Han, Tibetan, and Mongol RhD-positive donors, whereas a 1228-bp product was detected in RhD-negative donors. The sequences of RHCE gene intron 4 were identical to each other in all Han, Tibetan, and Mongol RhD-negative donors, including 335 bp of Alu element, with a whole length of 1078 bp. By contrast, a 426-bp product was detected in all Han, Tibetan, and Mongol RhD-positive donors. Compared with the RHCE gene, a 652-bp deletion was noted in the RHD gene of Chinese, including the whole Alu element. The results were similar to the findings of Caucasians, whereas the lengths of RHD gene deletion fragments of Japanese and French were 649 and 654 or 651 bp, respectively. CONCLUSIONS: The RHCE gene intron 4 of Han Chinese, Tibetans, and Mongols differs from the RHD gene intron 4 in the presence of a 652-bp fragment. The RHCE gene intron 4 in Chinese has its own structural characteristics and differs among various ethnicities and regions.

[Polymorphism of M, N Allele in MN Blood Group of Chinese Population].

OBJECTIVE: To detect the base sequences of all exons and part of introns in the GYPA gene of the glycophorin GPA and to investigate the polymorphism of M, N alleles in Chinese population. METHODS: A total of 225 blood sample were randomly colleeted from unrelated Chinese volunteers and were detected by serology techniques. The primers were designed by self, the seguencing of GYPA gene related with sample exon 1-7 full length sequences of bases and intron-1-7 partial sequence was performed, the polymorphism of M, N gene mutation in mucleotide sequence was analysed. RESULTS: The results of M and N genotyping were in agreement with the results of serological detection. The 23rd base of intron-2, the 55th base of intron-3, the 63rd base of intron-4, the 55th, 189th and 190th base of intron-6, the 712th base variation of exon-7 in the gene M and N were used to subdivide the gene M and N into the mutant M103, M201, M202, N101, N102, N103, N104, and N201. At the same time, it was found that 42th and 54th base were mutated, the base T was inserted between 59th and 60th base in the intron-2, the new mutations occurred in the alleles 28, 29, 65 and 102 in intron-3 in this study. CONCLUSION: The polymorphism of the the Chinese population's GYPA gene occurs in all the exons and partly in the introns. The gene polymorphism of M and N blood group in Chinese population might provide the theoretical basis for the studies of clinical blood transfusion, human population genetics and molecular biology.

Indirect purification method provides high yield and quality ssDNA sublibrary for potential aptamer selection.

The quality and yield of single-stranded DNA (ssDNA) play key roles in ssDNA aptamer selection. However, current methods for generating and purifying ssDNA provides either low yield due to ssDNA loss during the gel purification process or low specificity due to tertiary structural damage of ssDNA by alkaline or exonuclease treatment in removing dsDNA and by-products. This study developed an indirect purification method that provides a high yield and quality ssDNA sublibrary. Symmetric PCR was applied to generate a sufficient template, while asymmetric PCR using an excessive nonbiotinylated forward primer and an insufficient biotinylated reverse primer combined with a biotin-strepavidin system was applied to eliminate dsDNA, hence, leading to ssDNA purification. However, no alkaline or exonuclease were involved in treating dsDNA, so as to warrant the tertiary structure of ssDNA for potential aptamer SELEX selection. Agarose gel imaging indicated that no dsDNA or by-product contamination was detected in the ssDNA sublibrary generated by the indirect purification method. Purified ssDNA concentration reached 1020±210nM, which was much greater than previous methods. In conclusion, this novel method provided a simple and fast tool for generating and purifying a high yield and quality ssDNA sublibrary.

[Alanine solution as enzyme reaction buffer used in A to O blood group conversion].

The aim of this study was to investigate the effect of alanine solution as α-N-acetylgalactosaminidase enzyme reaction buffer on the enzymatic activity of A antigen. The binding ability of α-N-acetylgalactosaminidase with RBC in different reaction buffer such as alanine solution, glycine solution, normal saline (0.9% NaCl), PBS, PCS was detected by Western blot. The results showed that the efficiency of A to O conversion in alanine solution was similar to that in glycine solution, and Western blot confirmed that most of enzymes blinded with RBC in glycine or alanine solution, but few enzymes blinded with RBC in PBS, PCS or normal saline. The evidences indicated that binding of enzyme with RBC was a key element for A to O blood group conversion, while the binding ability of α-N-acetylgalactosaminidase with RBC in alanine or glycine solution was similar. It is concluded that alanine solution can be used as enzyme reaction buffer in A to O blood group conversion. In this buffer, the α-N-acetylgalactosaminidase is closely blinded with RBC and α-N-acetylgalactosaminidase plays efficient enzymatic activity of A antigen.

HLA polymorphism and susceptibility to end-stage renal disease in Cantonese patients awaiting kidney transplantation.

BACKGROUND: End-Stage Renal Disease (ESRD) is a worldwide public health problem. Currently, many genome-wide association studies have suggested a potential association between human leukocyte antigen (HLA) and ESRD by uncovering a causal relationship between HLA and glomerulonephritis. However, previous studies, which investigated the HLA polymorphism and its association with ESRD, were performed with the modest data sets and thus might be limited. On the other hand, few researches were conducted to tackle the Chinese population with ESRD. Therefore, this study aims to detect the susceptibilities of HLA polymorphism to ESRD within the Cantonese community, a representative southern population of China. METHODS: From the same region, 4541 ESRD patients who were waiting for kidney transplantation and 3744 healthy volunteer bone marrow donors (controls) were randomly chosen for this study. Polymerase chain reaction-sequence specific primer method was used to analyze the HLA polymorphisms (including HLA-A, HLA-B and HLA-DRB1 loci) in both ESRD patients and controls. The frequencies of alleles at these loci and haplotypes were compared between ESRD patients and controls. RESULTS: A total of 88 distinct HLA alleles and 1361 HLA A-B-DRB1 haplotypes were detected. The frequencies of five alleles, HLA-A*24, HLA-B*55, HLA-B*54, HLA-B*40(60), HLA-DRB1*04, and one haplotype (HLA-A*11-B*27-DRB1*04) in ESRD patients are significantly higher than those in the controls, respectively. CONCLUSIONS: Five HLA alleles and one haplotype at the HLA-A, HLA-B and HLA-DRB1 loci appear to be associated with ESRD within the Cantonese population.

[Analysis of HLA haplotype frequency and linkage disequilibrium in patients with acute lymphoblastic leukemia from Northern Chinese Han].

OBJECTIVE: To analyze the difference between the frequencies of HLA-A-B, B-DRB1 and A-B-DRB1 haplotype, as well as their linkage disequilibrium pattern in patients with acute lymphoblastic leukemia(ALL) and healthy controls from Northern Chinese Han. METHODS: The frequencies of HLA-A-B, B-DRB1, A-B-DR haplotypes and linkage disequilibrium were estimated by Expectation Maximization method based on the genotypes of 643 patients with ALL and 2 0359 unrelated healthy donors, and the statistical significance between the two groups were estimated by chi-square test. Linkage disequilibrium was analyzed with population genetic methods. RESULTS: The most common HLA-A-B, B-DRB1, and A-B-DR haplotypes were A30-B13, A2-B46, A33-B58, B13-DR7, B46-DR9, B52-DR15, B58-DR17, A30-B13-DR7, A33-B58-DR17 and A1-B37-DR10 in both groups. The frequencies of A30-B13, A2-B46, A33-B44, B13-DR7, A30-B13-DR7 and A2-B46-DR9 haplotypes and linkage disequilibrium value were significantly decreased (P<0.05) in the patient group than that in the control group. On the other hand, the frequencies of A2-B52, A31-B61, A24- B8, B60-DR9, B27-DR4, B52-DR14, B44-DR17, B27-DR12 and A11-B27-DR12 haplotypes and linkage disequilibrium value were significantly increased (P<0.05) in the patient group than that in the control group. CONCLUSION: There are some common and positive linkage disequilibrium haplotypes in both the ALL patients and the healthy donors in Northern Chinese Han. Interestingly, some haplotypes and their linkage disequilibrium patterns had significantly different distributions between the two groups. The study provided basic data for the relationship of ALL and HLA haplotype and for finding the HLA-A, B, DR matching donors.

[Establishment of the method to induce and measure human IL-2 in vitro].

This study was aimed to establish the quantitative analysis of hIL-2 in culture supernatant by multifunctional Luminex 100. The lymphocytes were separated from ACD-anticoagulated peripheral blood by density gradient method. The lymphocytes were stimulated with PHA for 48 hours, and frozen at -20 degrees C The relative fluorescence units of standard preparations and samples were detected by multifunctional Luminex 100, and the sample concentrations were calculated by standard curve. The results indicated that the regression equation of standard preparation is Lg (RFU) = 1.547 + 0.867 LgC. ANOVA F = 301.7427, p < 0.05 (nu = 6). The analysis of variance showed F = 301.7427, p < 0.05 (nu = 6). The test of regression coefficient showed t = 17.3707 (nu = 6), p < 0.05. It is concluded that method for induction and measurement of human IL-2 in vitro is established. The standard curve established by this way is statistically significant. There is linear relationship between the concentration of hIL-2 and fluorescence intensity.

Ex vivo expansion of CD34+ and T and NK cells from umbilical cord blood for leukemic BALB/C nude mouse transplantation.

CBSCT with low incidence of GVHD is associated with higher rates of delayed engraftment and relapse compared with other stem cells transplants. The immune-mediated effect of NK and cytotoxic T cells against residual tumor cells was shown to prevent relapse and reinduce remission after bone marrow transplantation. We expanded CD34+ and T and NK cells ex vivo in cord blood with different cytokines combination and transplanted into leukemic BALB/C nude mouse. The results showed significant expansion of MNCs and CD34+ cells. The CD3+ T cells increased in the groups containing cytokines cocktail, especially in the group with IL-7 or IL-2. CD56+ NK cells number increased significantly only in a medium containing IL-2. Of the 20 engrafted BALB/C nude mice, 14 survived after 6 weeks transplantation, and the numbers in each group were from 3 to 4. Human CD3+ cells in the bone marrow of the survived mice were analyzed by flow cytometry and showed existing evidences. RT-PCR was used to detect leukemic fusion bcr/abl gene; all mice that experienced expanded cord blood transplantation could not be found to have expression of fusion bcr/abl gene. These suggest that T, NK cells as well as CD34+ cells could be expanded from CB MNCs in the same medium with the combination of cytokines. The expanded CB MNCs could reconstitute hematopoiesis and eliminate minimal residue leukemia disease in transplanted mice.

[Comparison between genotyping and serological phenotyping in RhCE blood group].

OBJECTIVE: To genotype the RHCE gene of Hans, Xinjiang's Uigurs and Kazakstans in China, and to compare the results of RHCE genotyping with that of RhCc/Ee phenotyping. METHODS: RHCE genes of 98 Hans with RhD positive and 230 Hans, 72 Uigurs and 18 Kazakstans with RhD/RHD negative were genotyped with PCR-sequence specific primer (SSP) technique. RESULTS: The results of RHE/RHe genotyping from samples with RhD positive and negative were in accord with that of phenotyping. It would result in 4.44% error using C-->G polymorphism at nt48 of RHCE gene to genotype RHCE, and 4.05% failure of detection using the 109 bp insertion to detectRHCE gene in Chinese Hans. The results of RHE/RHe genotyping in unrelated 72 Uigurs and 18 Kazakstans with RhD phenotype were consistent with that of phenotyping, and false positive and false negative were not found in genotyping in Uigurs and Kazakstans tested. CONCLUSION: The results of RHE/RHe and RHc genotyping were correct with PCR-SSP and accordant with that of phenotyping. Using the C48G polymorphism in exon 1 of RHCE to genotype RHC gene would result in false positive resulting from RHc mutation at this locus, and using the 109 bp insertion to genotype RHC gene would result in false negative because of the absence of the 109 bp. Therefore it is necessary to genotype RHC gene using more than two polymorphic loci.

[Effect of platelet CD42a modification by mPEG-SPA with different molecular masses].

OBJECTIVE: To observe the effect platelet antigen modification by mPEG-SPA with different molecular masses. METHODS: Platelet CD42a was modified by 5 kD and 20 kD mPEG-SPA, respectively, and the fluorescence intensity of CD42a was detect by flow cytometry and the three-dimensional structure of CD42a simulated to analyze the distribution of lysine in CD42a molecule. RESULTS: After platelet CD42a modification by 5 kD and 20 kD mPEG-SPA, the fluorescence intensity of CD42a decreased sharply by 85.54% and 88.65%, respectively, and multiple lysine regions were identified on the surface of CD42a molecule. CONCLUSION: Both 5 kD and 20 kD mPEG-SPA allow useful modification of platelet CD42a, but 20 kD mPEG-SPA is more advantageous than 5 kD mPEG-SPA.

[A comparative research on RHD gene structures of Chinese Han and Uigur population].

OBJECTIVE: To research comparatively on the RHD gene structures in unrelated RhD negative individuals of Chinese Uigur and Han population. METHODS: The upstream, downstream, hybrid box and 10 exons of RHD gene were detected with sequence specific primer-PCR technique. RESULTS: The results showed the genotypes of RhD negative individuals to have the significant difference between Chinese Uigur and Han population, that 94.44% Uigur individuals were with RHD(-)/RHD(-) genotype but just 61.40% Han population were with this genotype(94.44% versus 61.40%, P<0.01); 2.78% Uigur individuals were with RHD(+)/RHD(-) genotype but 34.21% Han population were with this genotype(2.78% versus 34.21%, P<0.01). However, there was significantly no RHD(+)/RHD(+) genotype difference between Chinese Uigur and Han population(2.78% versus 4.39%, P>0.05). In 78 cases of RhD negative Chinese Hans with single RHD gene, of which the RHD gene structure showed that 53(67.95%) cases were RHD(1-10) allele(of 53 RHD(1-10) alleles, 14 alleles were unexpressed); 15(19.23%) were RHD-CE(2-9)-D(2) allele; 5(6.41%) cases were RHD-CE(2-7)-D(2) allele; 2(2.56%) were similar to RHD-CE(3-6)D allele; 1(1.28%) case was RHD-CE(5-6)-D allele; and 2(2.56%) were RHD-CE(6)-D or point mutation respectively. Of 2 RhD negative Chinese Uigurs with RhD(-)/RHD(+) genotype, one carried RHD(1-10) allele, another carried RHD-CE(2-9)-D(2) allele. CONCLUSION: The most frequently unexpressed RHD alleles were RHD-CE(2-9)-D(2), RHD(1-10) and RHD-CE(2-7)-D(2) respectively in Chinese Han population who carried single RHD allele with RHD(-) phenotype and RHD(+) genotype. It showed the confluent character of RH gene in Chinese Han and Uigur population that there existed unexpressed RHD-CE(2-9)-D(2) allele in Chinese Uigur nationality, which was infrequent in Chinese Uigur population but frequent in Chinese Han population.

[Comparison of Rhesus boxes in Hans and Uighurs].

OBJECTIVE: To study the difference and similarity between Hans and Uighurs in regard to Rhesus box and its significance. METHODS: The sequence specific primers of upstream, downstream and hybrid Rhesus boxes were designed on the basis of RHD gene sequence. The upstream, downstream and hybrid Rhesus boxes were determined by polymerase chain reaction-sequence specific primer(PCP-SSP) and mismatched PCR. RESULTS: The percentage of RHD-/RHD-, RHD+/RHD- and RHD+/RHD+ genotypes ascertained in the unrelated Hans with RhD(-) were 61.40%, 34.21% and 4.39% respectively, while those in the unrelated Chinese Uighurs with RhD(-) were 94.44%, 2.78% and 2.78% respectively. Furthermore, all 6 cases of some other minorities were RHD-/RHD- types. The percentage of RHD-/RHD- and RHD+/RHD- genotypes ascertained in the unrelated Chinese Uighurs were significantly higher than those in Chinese Hans (P < 0.01), whereas no statistically significant difference in the percentage of RHD+/RDH+ genotype between the two groups was observed (P > 0.05). CONCLUSION: The Rh blood group of Uighurs in Xingjiang possesses both Oriental and Caucasian characteristics, which embodies a special ethnical aspect of the Chinese nation and is in accord with the anthropologic research results.

[Determination of human RHD gene rhesus box and its significance].

The aim was to determine RHD zygosity, further to investigate genetic structure of RHD gene, and to predict hemolytic disease of newborn (HDN). The upstream box, downstream box, and hybrid box of RHD gene were determined by PCR-SSP with 4 primers under the same conditions. The results showed that only hybrid box could be determined in RHD(-)/RHD(-) homozygosity. All the upstream box, downstream box, and hybrid box could be determined in RHD(+)/RHD(-) heterozygosity, while upstream box and downstream box except hybrid box could be determined in RHD(+)/RHD(+) homozygosity. Out of 50 cases of RhD(+), 5 cases (10%) were RHD(+)/RHD(-) heterozygosity, and the others (90%) were RHD(+)/RHD(+) homozygosity. 54 cases (55.1%), 36 cases (36.7%) and 8 cases (8.2%) were RHD(-)/RHD(-) homozygosity, RHD(+)/RHD(-) heterozygosity, and RHD(+)/RHD(+) homozygosity respectively in 98 unrelated cases of RhD(-) Chinese Hans. 2 cases of weak D were proved to be RHD(+)/RHD(-) heterozygosity. Out of 16 D(el) types, the upstream box, downstream box, and hybrid box could be determined in 10 cases (37.5%) and the upstream box and downstream box except hybrid box could be determined in 6 cases. Results detecting of RHD 10 exons in above samples proved the correctness of the method. It is concluded that the method is suitable for clinical application with its simplicity and veracity. There are many noneffective RHD genes (44.9%) in Chinese Hans with RhD(-) phenotype.

[Method of detection of soluble HLA-I and soluble HLA-I level alteration in storage blood].

Aim of this study was to develop the detection method of soluble human leukocyte antigens I (sHLA-I) and to explore sHLA-I level alteration in storage blood and its significance. sHLA-I level in sera of 60 Guangdong normal individuals and sHLA-I concentration in blood components from 20 donors quantitatively were detected by sandwich ELISA. The results showed that sensitivity of this assay was 2.84 ng/ml. Coefficients of variation were 5.80% within assays and 9.00% between assays respectively. The recovery rate was >/= 98.57%. The sHLA-I level of normal individuals in Guangdong was (699.54 +/- 360.10) ng/ml. sHLA-I in red blood cells stored for 28 days and in random-donor platelets were significantly higher than that in other blood components and their amount was proportionate to the number of residual donor leukocytes and to the length of storage. In conclusion, sandwich ELISA assay for detection of sHLA-I is a sensitive, specific and stable technique. Blood components with different concentration of sHLA-I may be chosen for clinical transfusion.

[ABO blood group typing for infants and its application for clinical transfusion].

To study the correct method for determining ABO blood types in infants and its influencing factors, blood types of 33 infants under 6 months old were determined by routine serological method, micro-column gel typing system and PCR-SSP genotyping method. Of the 33 cases with discrepant results of ABO blood type by different methods, the blood types of 32 cases were discrepant between red cell and serological typings in the routine serological method, and a false coincidence in 1 case was caused by bacterial infection resulting in B-like antigen. Correct blood typing was obtained in 27 cases with a correct rate of 84.4% (27/32) by using micro-column gel typing system. PCR-SSP method gave correct results in all of 33 cases. There was a significant difference between the results of micro-column gel typing system and PCR-SSP. It is concluded that to determine ABO blood type for infants < 6 months old, it is recommended to adopt micro-column gel typing system method, and what must be taken into account is the possible false coincidence caused by bacterial infection resulting in B-like antigen. In micro-column gel typing system, if the results of red cell and serological typing are identical, the principle is that blood transfusion must be performed with same ABO blood type between recipient and donor. If not, washed O red blood cells should be used for infants, and then change to transfusion with identical blood group according to PCR-SSP typing results.