Introducing a dexamethasone mouse model for monitoring in vivo viability of stored human platelets.

OBJECTIVES: The aim of this study is to establish an available animal model which can evaluate in vivo viability of stored human platelets (HuPLTs). BACKGROUND: The viability in vivo of HuPLTs was usually evaluated by transfusing HuPLTs into animals before clinical trials. It is necessary to develop a method which may slow down rapid clearance of HuPLTs from circulation of the animal. METHODS: Carbon clearance tests were performed by treating mice with dexamethasone (DEX) to determine the phagocytic ability of the mice macrophages. HuPLTs in mice whole blood were detected by flow cytometric analysis with mouse anti-human CD41-fluorescein isothiocyanate monoclonal antibody. Recovery and survival of the HuPLTs stored at 22 °C for 1 day were evaluated after transfusing these HuPLTs into DEX-treated mice, and compared with those either stored at 22 °C for 5 days or at 4 °C for 1 day. RESULTS: Corrected phagocytic indexes of DEX-treated mice decreased significantly compared with those of control mice (P < 0.05). The recovery after 24 h and survival time of fresh HuPLTs in DEX-treated mice were much higher than those in control mice (P < 0.01). After transfused into the DEX-treated mice, HuPLTs stored either at 22 °C for 5 days or at 4 °C for 1 day showed decrease in recovery and survival compared with those stored at 22 °C for 1 day (P < 0.05). CONCLUSION: Dexamethasone slows down the rate of HuPLTs clearance efficiently in mouse circulation. And the DEX-treated mouse model was able to evaluate the in vivo viability of stored HuPLTs.

Prevalence of immunoglobulin A deficiency in Chinese blood donors and evaluation of anaphylactic transfusion reaction risk.

OBJECTIVES/AIMS: We investigated the incidence of immunoglobulin A (IgA) deficiency in Chinese population. BACKGROUND: The frequency of IgA deficiency, defined as a serum IgA level of <0.05 mg dL(-1) , has been broadly studied in different ethnic groups. Individuals with IgA deficiency may form specific antibodies against IgA, which can cause an anaphylactic response when the patient receives an IgA-containing blood transfusion. METHODS: A sandwich enzyme-linked immunosorbent assay was performed to screen for IgA deficiency and particle gel immunoassay used for confirmation. IgA antibodies were further detected by the DiaMed anti-IgA test in IgA-deficient blood donors. RESULTS: Of the total 22,609 healthy blood donors screened, only seven cases were confirmed as having IgA deficiency (<0.05 mg dL(-1) ). Another seven cases displayed relative IgA deficiencies, with mean IgA concentrations ranging from 0.39 to 3.70 mg dL(-1) . Anti-IgA was identified in 2 of the 14 IgA-deficient blood donors whose IgA levels were <5 mg dL(-1) . Estimation of the theoretical risk for IgA anaphylactic transfusion reaction was 0.009%. CONCLUSION: The prevalence of IgA deficiency in Chinese is low. However, potential risks exist in performing blood transfusion to IgA-deficient persons, and measures should be taken to reduce IgA anaphylaxis.

Determination of TAP1 and TAP2 polymorphism in the Chinese Han population by real-time TaqMan polymerase chain reaction.

The heterodimeric transporter associated with antigen processing (TAP) complex plays a key role in immune surveillance. TAP1 and TAP2 typing was usually performed by polymerase chain reaction (PCR)-restriction fragment length polymorphism and PCR-sequence-specific oligonucleotide probe. As an alternative to these methods, we have established TaqMan assays to determine the frequencies of the TAP1 and TAP2 alleles. We have used these new TaqMan assays to genotype the polymorphisms in 339 unrelated Chinese Hans residing in North and South China. We detected five TAP1 and four TAP2 alleles. All the loci conform to the Hardy-Weinberg expectations. The most frequent alleles in Chinese Hans were TAP1*0101 (79.79%) and TAP2*0101 (82.74%). The two-locus haplotype analysis showed highly significant positive linkage disequilibrium for one TAP1-TAP2 haplotype (TAP1*020101-TAP2*0102), three TAP1-DRB1 haplotypes (TAP1*020101-DRB1*03, TAP1*020102-DRB1*13, and TAP1*0301-DRB1*16), and three TAP2-DRB1 haplotypes (TAP2*0102-DRB1*09, TAP2*0103-DRB1*04, and TAP2*0201-DRB1*01). The three-locus haplotype analysis showed highly significant positive linkage disequilibrium for TAP1*0101-TAP2*0101-DRB1*07, TAP1*0101-TAP2*0103-DRB1*04, TAP1*020101-TAP2*0101-DRB1*03, and TAP1*020101-TAP2*0102-DRB1*13. Comparison of the allele frequencies with those of other populations showed that the TAP1 allele distribution was very similar in all the groups, except for the Guarani, Kaingang, and Anatolian populations, but TAP2 distribution was significantly different from that of the other populations. The new TaqMan method provides relatively accurate, high-resolution, simple, and fast assays for TAP genotyping.

Structure-based design and subsequent optimization of 2-tolyl-(1,2,3-triazol-1-yl-4-carboxamide) inhibitors of p38 MAP kinase.

A computer-aided drug design strategy leads to the identification of a new class of p38 inhibitors based on the 2-tolyl-(1,2,3-triazol-1-yl-4-carboxamide) scaffold. The tolyl triazole amides provided a potent platform amenable to optimization. Further exploration leads to compounds with greater than 100-fold improvement in binding affinity to p38. Derivatives prepared to alter the physicochemical properties produced inhibitors with IC(50)'s in human whole blood as low as 83 nM.

Establishment of an HPA-1- to -16-typed platelet donor registry in China.

In order to determine gene frequencies of human platelet antigen (HPA) and establish a panel of accredited HPA-1a, -2a, -4a, -5a and -6a-negative donors as well as an HPA-typed platelet donor registry, a total of 1000 Chinese donors of Han nationality (500 from north China and 500 from south China) were typed for HPA-1 through -16 using a DNA-based polymerase chain reaction with sequence-specific primers genotyping method. The gene frequencies of HPA-1b, -2b, -3b, -4b, -5b, -6bw, -10bw and -15b were 0.0060, 0.0485, 0.4055, 0.0045, 0.0140, 0.0135, 0.0005 and 0.4680, respectively. The HPA-7bw, -8bw, -9bw, -11bw, -12bw, -13bw, -14bw and -16bw alleles were not found. The HPA-2b and -5b homozygous donors were detected at low frequencies. The HPA mismatch probabilities potentially leading to alloimmunization in random platelet transfusion vary with a region from 0.1% to 37% depending on the distribution patterns of common and less common alleles in each system. This study provides a useful HPA-typed plateletpheresis donor registry in China and could improve platelet antibody detection and HPA-matched platelet transfusion in alloimmune thrombocytopenic patients.

Study on the haplotypes of MICA and MICB microsatellite and HLA-B locus in the Guangzhou Han population.

The purpose of this study was to investigate the genetic polymorphisms and haplotypes of microsatellite locus in exon 5 of the MICA gene and intron 1 of the MICB gene and human leukocyte antigen-B (HLA-B) gene based on 106 samples of the Guangzhou Han population through means of polymerase chain reaction and the fluorescent technique (6-FAM). The corresponding haplotype frequencies, linkage disequilibrium values and relative linkage disequilibrium values were estimated based on population data. The results show that the genotype distributions of MICA and MICB microsatellite and HLA-B satisfy the Hardy-Weinberg equilibrium. In total, five alleles of MICA microsatellite locus and 14 alleles of MICB microsatellite locus were observed. MICA A5 was the most common allele (0.2877), whereas A4 was the least common (0.1321). MICB CA14 was the most common allele (0.3255), and CA19 and CA28 were the two least common (0.0047). CA27 was not observed at all. Five kinds of MICA-MICB haplotypes, 18 kinds of MICA-HLA-B haplotypes and 12 kinds of MICB-HLA-B haplotypes occurred at frequencies of more than 1%. The common haplotypes of MICA-MICB, MICA-HLA-B and MICB-HLA-B were A5-CA14, A5.1-CA18, A4-CA26, A9-CA15, A5-B*15(62), A5.1-B*1301/1302, A4-B*1301/1302, A6-B*51, A6-B*4403, A9-B*3802, CA14-B*4601, CA18-B*1301/1302 and CA26-B*1301/1302, and these haplotypes showed strong linkage disequilibrium. The polymorphisms and haplotype distributions of MICA and MICB microsatellite and HLA-B locus in the Guangzhou Han population have their own distinct genetic characteristics. The microsatellite locus of exon 5 of the MICA gene and intron 1 of the MICB gene could therefore be used as genetic markers in the studies of anthropology, gene linkage analysis in genetic diseases, individual identification and paternity testing in forensic medicine.

The effect of acidified glucose nutrient solution on preservation of platelet concentrate.

The preservation effect of a new platelet solution--acidified glucose nutrient solution (AGN)--was tested by adding AGN to pooled platelet rich plasma (PRP) prior to preparation of platelet concentrates (PC). Each PRP unit was prepared from a unit of whole blood and four PRP of the same blood group were pooled in 400 ml volume PVC bags. Equal aliquots of each pooled PRP were made prior to preparation of PC. AGN was added to one aliquot and nothing was added to the control aliquot. Equal volume and concentration PC were then prepared and the PC were further aliquoted for storage at 22 degrees C. After five days, the parameters of platelet count, pH, aggregability and hypotonic shock response (HSR) for PC preserved in AGN plasma were better than those of the controls preserved in normal ACD plasma. The aggregability and HSR of AGN platelet concentrates recovered to baseline after two h of incubation with fresh plasma. The results of electron microscopy show that platelets preserved in AGN have less changes in morphology. The results of our work suggest that the preservation effect of AGN on PC is similar to the effect of using second generation containers or preparation of platelets from thrombocytapheresis.