Polymorphisms of the human platelet alloantigens HPA-1, HPA-2, HPA-3, and HPA-4 in ischemic stroke

Polymorphism in human platelet antigen (HPA)-1 and HPA-3 (GPIIb/IIIa), HPA-2 (GPIb/IX), HPA-4 (GPIIIa), and HPA-5 (GPIa/IIa) was investigated in 329 stroke patients and 444 matched control subjects. HPA genotyping was done by PCR-SSP method. Lower HPA-1a (P < 0.001) and higher HPA-1b (P < 0.001) allele frequencies were seen in patients than control subjects, and homozygosity for HPA-1b (P < 0.001) alleles was more prevalent in stroke cases than in controls. The allele and genotype distributions of the other HPA polymorphic variants were similar between cases and controls. Select HPA combined genotypes comprising the 2121 (Pc = 0.008) and 2221 (Pc = 0.018) genotypes, which were positively associated, and the 1111 (Pc < 0.001), which was negatively associated with stroke, thereby conferred a disease susceptibility and protective nature to these genotype combinations. Multivariate analysis confirmed the negative association of the 1111 (P < 0.001) and the positive association of the 2121 (P = 0.017) combined genotypes with stroke, after adjustment for a number of covariates. This is the first evidence demonstrating differential association of the common 4 HPA gene variants and specific HPA genotype combinations with stroke.     

Allele Frequencies of Human Platelet Antigen 1, 2, 3, and 5 Systems in Patients with Chronic Refractory Autoimmune Thrombocytopenia and in Normal Persons

BACKGROUND AND OBJECTIVES: Chronic refractory autoimmune thrombocytopenic purpura (AITP) is an autoimmune disorder due to autoantibodies against platelet glycoproteins (GP). Human platelet alloantigenic (HPA) systems are distributed to different platelet GPs. We carried out genotyping of diallelic HPA-1, -2, -3, and -5 systems to clarify potential associations between HPA alleles and the development of chronic refractory AITP. PATIENTS AND METHODS: DNA was isolated from 33 unrelated German patients with chronic refractory AITP and from 80 randomly selected German blood donors to determine the phenotype and allele frequencies for the HPA-1, -2, -3, and -5 systems. Fragments carrying the polymorphic sequences corresponding to those alleles were amplified by the polymerase chain reaction and further characterized by restriction analysis. RESULTS: Whereas HPA-1, -3, and -5 allele frequencies were identical in 33 patients with chronic refractory AITP and in controls, HPA-2 allele frequencies showed a statistically significant difference (p = 0.017). In our group of patients, the HPA-2a allele frequency was 100%, but HPA-2b was not seen. In contrast, the allele frequency of HPA-2a in the control group was 92% (n = 147), and in HPA-2b it was 8% (n = 13). CONCLUSION: This study suggests an association between the HPA-2a allele and chronic refractory AITP. The HPA-2a allele may be involved in the formation of an AITP-specific autoepitope.     

洛阳地区献血员人类血小板抗原1～10频率分布调查

目的:研究洛阳地区献血员人类血小板抗原(HPA)1~10基因多态性,为患者提供HPA相配合的血小板。方法:随机收集250例无偿献血员样本,应用聚合酶链式反应-序列特异引物(PCR-SSP)技术检测HPA-1~10基因型及等位基因频率。结果:HPA-1aa、-1ab所占百分比分别为98.80%和1.20%,HPA-2aa、-2ab所占百分比分别为90.80%和9.20%,HPA-4aa、-4ab所占百分比分别为98.00%和2.00%,HPA-5aa、-5ab所占百分比分别为96.40%和3.60%,HPA-aa、-ab、-bb三种基因型在HPA-3和HPA-6中的比例分别为29.20%、46.00%、24.80%和91.60%、6.80%、1.60%,在HPA-7、-8、-9、-10中仅检测到HPA-aa纯合子。结论:洛阳地区HPA-1~HPA-10基因分布与文献报道相似,HPA-3特异性抗体是引起本地区HPA同种免疫性疾病的首要原因。     

Gene frequencies of the HPA-1 to HPA-8w platelet antigen alleles in Taiwanese,Indonesian, and Thai

Human platelet antigen (HPA) systems consist of more than eight biallelic antigen polymorphisms in which a base pair substitution leads to change in an amino acid of a glycoprotein expressed on the platelet. HPA typing is essential in the diagnosis and treatment for a variety of diseases. We developed a polymerase chain reaction (PCR)-based method to detect HPA-1 through HPA-8w. In this method, the amplified PCR products were used to recognize the polymorphism after restriction enzyme digestions. Among 295 Taiwanese, 107 Indonesian, and 137 Thai subjects studied, HPA-1a, 2a, 4a, 5a, 6a, 7aw, and 8aw genes were present in every sample tested. HPA-1b, 2b, 4b, 5b, and 6b were rarely found among subjects. Only monomorphic HPA-7aw and 8aw alleles were noted in the samples. HPA-3a and 3b alleles showed frequencies of 0.595/0.405, 0.504/0.496, and 0.507/0.493 in Taiwanese, Indonesian, and Thai subjects, respectively. Our report is the first PCR-based method to detect most of the HPA antigen variants in Taiwanese, Indonesian, and Thai. The genomic typing results were also confirmed by direct sequencing for uncertain and some representative cases. The prevalence rates of HPA-1, 2, 3, 4, and 5 in this study were also consistent with other previous reports using different methods.     

Determination of human platelet antigen frequencies in the Dutch population by immunophenotyping and DNA (allele-specific restriction enzyme) analysis

Platelets from 200 random Dutch blood donors were typed for the human platelet alloantigens HPA-1 to -5 recognized at present and for Naka. Naka is an epitope on glycoprotein IV, not expressed on the platelet of individuals with hereditary GP IV deficiency. Platelet immunofluorescence and monoclonal antibody-specific immobilization of platelet antigens (MAIPA) were applied for this purpose. The observed phenotype frequencies were 97.86% and 28.64% for HPA-1a and -1b, 100% and 13.15% for HPA-2a and -2b, 80.95% and 69.84% for HPA-3a and -3b, 100% and 0% for HPA-4a and -4b, 100% and 19.7% for HPA-5a and HPA-5b, respectively. Platelets from all donors reacted with the anti-Naka antibodies. To determine the gene frequencies for the HPA-1, HPA-2 and HPA-3 systems directly, DNA from 98 of these donors was isolated from peripheral blood mononuclear leucocytes and specific fragments were amplified by polymerase chain reaction (PCR). The fragments were analyzed using allele-specific restriction enzymes (ASRA). In all amplified PCR products an "internal control" for each assay, ie, a restriction site for the applied enzyme independent from the phenotype of the donor was present. In all donors tested, phenotypes, as determined by serological methods and genotypes, directly determined by the ASRA, were identical. Thus, the PCR-ASRA described in this report is a practical and reliable technique for the determination of alleles that code for platelet antigen allotypes, at least in the Dutch population.     

Human platelet alloantigens (HPA) 1, HPA2, HPA3, HPA4, and HPA5 polymorphisms in sickle cell anemia patients with vaso‐occlusive crisis

Objectives: Vaso‐occlusive crisis (VOC) is a significant cause of morbidity and mortality in sickle cell anemia (SCA) patients. Insofar as polymorphism in human platelet alloantigen (HPA) exhibit a prothrombotic nature, we hypothesized that specific HPA polymorphic variants are associated with VOC. We investigated the distribution of HPA1, HPA2, HPA3, HPA4, and HPA5 alleles genotypes among VOC and non‐VOC control SCA patients. Patients/methods: This was a case–control study. Study subjects comprised SCA patients with (VOC group; n = 127) or without (Steady‐state group; n = 130) VOC events. HPA genotyping was done by PCR‐SSP. Results: Significantly higher frequencies of HPA‐2b, HPA‐3b, and HPA‐5b alleles, and marked enrichment of HPA‐3b/3b, HPA‐5a/5b, and HPA‐5b/5b genotypes, were seen in VOC than in control SCA patients. Taking homozygous wild‐type genotypes as reference, univariate analysis identified HPA‐3a/3b, HPA‐3b/3b, and HPA‐5b/5b to be associated with VOC. Multivariate analysis confirmed the independent association of only HPA‐3a/3b and HPA‐3b/3b genotypes with VOC. HPA‐3 genotypes were significantly correlated with VOC frequency, type, and medication, and requirement for hospitalization. While both HPA 3a/3b (P = 0.002; OR = 2.94; 95% CI = 1.49–5.77) and 3b/3b (P = 0.006; OR = 3.16; 95% CI = 1.40–7.17) genotypes were associated with need for hospitalization, only HPA‐3b/3b was associated with VOC frequency, type (localized vs. generalized), and medication (narcotics vs. NSAIDs). Conclusion: This confirms the association of HPA polymorphisms with SCA VOC, of which HPA‐3 appears to be independent genetic risk factors for SCA VOC.     

武汉地区人群血小板特异性基因(HPA-1～17)的多态性分析

目的:研究武汉地区人群HPA-1~17基因的多态性及其表达频率,建立HPA基因型资料库。方法:采用序列特异性引物-聚合酶链反应(SSP-PCR)对284名健康的已加入中华骨髓库的血小板捐献者HPA基因进行分型,计算基因型频率、基因频率。结果:武汉地区健康血小板捐献者中检测出HPA-a基因中的1a~17a基因;各基因独立的分布频率中,HPA-1a(98.77%)、2a(97.01%)、3a(59.68%)、4a(99.82%)、5a(99.82%)、6a(98.42%)、15a(49.47%),HPA-7a~14a、16a和17a均为100%。仅检测出HPA-b基因中HPA-1b(1.23%)、2b(2.99%)、3b(40.32%)、4b(0.18%)、5b(0.18%)、6b(1.58%)、15b(50.53%),未检测出HPA-7b~14b、16b和17b。文中调查和分析了HPA基因组合型及其频率,发现武汉地区HPA基因有28种组合型,其中仅有3种基因组合型频率10%(44%),另外25种基因组合型的频率均9%(56%)。在与国内外不同地区人群HPA基因多态性分布的比较分析中发现,武汉地区人群中HPA基因频率与上海、成都地区人群没有差异性,与美国、英国、欧洲人群有较有明显差异,而与日本人群的差异较小。结论:HPA-3、15系统具有多态性,在随机血小板输注中,供受者HPA-3、HPA-15系统不配合的机会分别为36.54%、37.50%,是HPA配合性输注关注重点。HPA基因多态性研究数据有利于指导地区性血小板供者库库容的设计,配合临床开展选择适合性血小板输注具有重要意义。     

Human platelet alloantigens HPA-1, HPA-2, and HPA-3 polymorphisms associated with extent of severe coronary artery disease

The contribution of human platelet antigen (HPA)-1 (GPIIb/IIIa), HPA-2 (GPIb/IX), and HPA-3 (GPIIb/IIIa) polymorphisms to the risk of coronary artery disease (CAD) was investigated in 341 CAD patients and 316 matched control subjects. HPA genotyping was performed by PCR-SSP. Regression analysis was employed in assessing the contribution of these variants to CAD risk. The frequency of HPA-1b (P = .009) and HPA-3b (P = .004) alleles, and HPA-1a/1b (P = .045), HPA-1b/1b (P = .007), and HPA-3b/3b (P = .008) genotypes were higher in patients than control subjects. No significant association was demonstrated between the HPA variants and 1-, 2- and 3-vessel disease. HPA-1b/2a/3b (Pc = .021) and HPA-1b/2b/3a (Pc = .002) haplotypes were positively associated with CAD, thereby conferring a disease susceptibility nature to these haplotypes. Multivariate analysis confirmed the positive association of HPA-1b/2a/3b (aOR = 3.72; 95% CI = 1.49–9.28), and in addition identified HPA-1b/2a/3a (aOR = 2.49; 95% CI = 1.06–5.86) to be positively associated with CAD, after adjusting for a number of covariates. Our results demonstrate positive association of HPA variants and specific HPA-1/HPA-2/HPA-3 haplotypes with CAD in Tunisians.     

Allelic polymorphisms of human platelets-specific alloantigens in South Tunisian population

Abstract

Objectives

Human platelet-specific alloantigens (HPA) are polymorphic epitopes which vary among ethnic groups.

Background

In Tunisia, HPA frequencies were determined in North and centre; however, the pattern of HPA in South Tunisian population is not been studied yet. The aim of this work was to determine allelic frequencies of HPA-1, -3, and -5 systems in south Tunisian population, in order to estimate the risk of anti-platelet allo-immunization and to create a register of HPA-typed blood donors.

Methods

Our study concerned 212 unrelated healthy, regular blood donors from southern Tunisia. Allelic polymorphisms of each system were determined using a polymerase chain reaction with sequence-specific primers.

Results

Genotype frequencies a/a, a/b, and b/b were, respectively, 0.670, 0.288, and 0.042 for HPA-1 system, 0.430, 0.462, and 0.108 for HPA-3 system, and 0.750, 0.241, and 0.009 for HPA-5 system. The allele frequencies were 0.814 and 0.186 for HPA-1a and -1b alleles; 0.660 and 0.340 for HPA-3a and -3b alleles and 0.870, and 0.130 for HPA-5a and -5b alleles.

Discussion

The reported frequencies are more similar to those of Caucasians than those of north Tunisian population.     

Antibody formation in pregnant women with maternal-neonatal human platelet antigen mismatch from a hospital in northern Taiwan

Neonatal alloimmune thrombocytopenia (NAIT) is a clinical syndrome that resembles hemolytic disease of the newborn, affecting the platelets only. The thrombocytopenia results from the maternal alloantibodies reacting with specific human platelet antigens (HPAs) on the fetal platelets. Forty-four maternal plasma samples were screened for platelet alloantibodies using qualitative solid phase enzyme-linked immunosorbent assay (ELISA) commercial kit (LIFECODES Pakplus, Hologic Gen-Probe GTI Diagnostics, Waukesha, WI, USA), and both the maternal and the corresponding cord blood samples were genotyped (LIFECODES ThromboType, Hologic Gen-Probe GTI Diagnostics, Waukesha, WI, USA). HPA genotyping results correlated with the genetic frequencies in the Taiwan population. A total of 34 newborns (77.3%) had partial HPA genotyping mismatches with the corresponding mothers. The most common partial mismatches between mothers and neonates in HPA genotypes were 13 (29.5%) in both HPA-3b and HPA-15a, followed by 12 (27.3%) in HPA-15b, and 8 (18.2%) in HPA-3a. The frequencies of homozygotic mother with heterozygotic neonate were 15.9% in both HPA-3a and HPA-15b, 9.1% in HPA-15a, 6.8% in HPA-3b, and 2.3% in both HPA-2a and HPA-6a. In this study, maternal HPA antibodies were found in five samples, whereas HLA class I antibodies were found in seven maternal plasma samples from the antibody screen. The results from this study have demonstrated that HPA mismatch is not the main cause for the production of HPA alloantibodies.     

Simultaneous Genotyping of Human Platelet Antigens by Hot Start Sequence-Specific Polymerase Chain Reaction with DNA Polymerase AmpliTaq Gold

Objectives: Human platelet alloantigen (HPA) typing has potential clinical relevance in a variety of contexts. We can improve methods for HPA genotyping by complementing our knowledge of the DNA sequence polymorphisms of HPA genes and experience with various DNA-based HPA typing techniques. Methods: A newly available DNA polymerase, AmpliTaq Gold (Perkin Elmer), provided in an inactive state and activated by heat, makes it possible to perform a hot start polymerase chain reaction (PCR) in order to prevent nonspecific amplification during the setup of PCR. To establish a practical procedure for HPA-1, 2, 3 and 5 genotyping, we applied the AmpliTaq Gold for a hot start PCR and employed 8 pairs of published sequence-specific primers (SSP). A simple simultaneous genotyping of these 4 HPA systems could be rapidly achieved with high specificity. Results: The HPA gene frequencies observed in 126 randomly selected German blood donors were 0.82 and 0.18 for HPA-1a and 1b, 0.92 and 0.08 for HPA-2a and 2b, 0.63 and 0.37 for HPA-3a and 3b and 0.90 and 0.10 for HPA-5a and Sb, respectively. Conclusion: Using our hot start PCR-SSP procedure with AmpliTaq Gold a simple, rapid and reproducible genotyping for HPA-1, 2, 3 and S systems could be achieved.     

Human platelet alloantigen polymorphism in Glanzmann's thrombasthenia and its impact on the severity of the disease

Glanzmann's thrombasthenia (GT) is an autosomal recessive disorder of platelets caused by the deficiency or abnormality of platelet receptors. Several platelet alloantigen systems reside on glycoprotein (GP) IIb and GPIIIa, of which the human platelet antigen 1 (HPA-1) system is important. Studies have shown that, in the normal population, the HPA-1b phenotype results in increased platelet aggregation and increased fibrinogen binding, increasing the risk of myocardial infarction. GT produces severe bleeding, but in a subset of patients has a relatively milder course. Forty-one GT patients and 100 healthy control subjects were genotyped for platelet alloantigens HPA-1 to HPA-6, using PCR-ASA (polymerase chain reaction-allele-specific amplification), and for GPIIb-IIIa expression and fibrinogen binding using flow cytometric techniques. Platelet alloantigen distributions were similar in the patient and control groups. With the exception of the two HPA-1b/1b homozygous patients (> 10%), 25 GT patients had less than 5% aggregation to 6 micro mol/l ADP, and 16 patients showed between 5% and 10% aggregation to 6 micro mol/l ADP. Seven out of 37 patients with HPA-1a/1a phenotype showed 1-5% fibrinogen binding and GPIIb-IIIa receptors. The two HPA-1b/1b patients showed 34.6% and 32% fibrinogen binding and > 10% GPIIb-IIIa receptors. This study determined the platelet alloantigen distribution in a large cohort of unrelated GT patients from western India. GT patients homozygous for HPA-1b/1b had higher levels of platelet aggregation and fibrinogen binding as well as a milder course, as evidenced by infrequent epistaxis and no transfusion requirement to date.     

Polymorphism of platelet glycoprotein IIb and risk of thrombosis and restenosis after coronary stent placement

Both glycoprotein (GP) IIb and IIIa of platelet fibrinogen receptor are polymorphic proteins. Unlike GPIIIa, there is little information about the clinical significance of the GPIIb polymorphism. We designed this prospective study to assess whether patients with the human platelet antigen (HPA)-3 polymorphism of GPIIb are more susceptible to developing thrombosis and restenosis after coronary stent placement. We included 2,178 consecutive patients with coronary artery disease who underwent intracoronary stent implantation, 789 (36.2%) with HPA-3a/a, 1,023 (47.0%) with HPA-3a/b, and 366 (16.8%) with HPA-3b/b genotype. The incidence of stent thrombosis was 1.7% in HPA-3a/a, 1.7% in HPA-3a/b, and 1.6% in HPA-3b/b patients (p = 0.999). The incidence of stent restenosis was 37.3% in HPA-3a/a, 36.2% in HPA-3a/b, and 34.6% in HPA-3b/b patients (p = 0.724). Event-free survival 1 year after stent placement was 76.1% for HPA-3a/a, 76.5% for HPA-3a/b, and 76.4% for HPA-3b/b patients (p = 0.968). We conclude that the HPA-3 polymorphism of platelet GPIIb is not associated with an increase in the risk of thrombosis and restenosis over 1 year after coronary stent placement. These data indicate that unlike the HPA-1 polymorphism of GPIIIa, the HPA-3 polymorphism of GPIIb may not serve as a useful genetic marker for the risk assessment of patients treated with intracoronary stenting.     

The effect of human platelet alloantigen polymorphisms on the in vitro responsiveness to adrenaline and collagen

A number of clinical studies have suggested that carriage of the low frequency allele (b) of the human platelet antigen 1 (HPA-1) system is a risk factor for coronary thrombosis. We have examined the effect of a series of HPA biallelic polymorphisms (systems -1, -2, -3 and -5) on the in vitro platelet aggregation in response to adrenaline and collagen in 30 healthy volunteers. There was a significantly higher prevalence (10 out of 18) of carriers of the HPA-1b polymorphism among subjects showing a > 50% aggregation response to adrenaline ('responders') than the prevalence (1/12) in 'non-responders' (P < 0.05). Platelets heterozygous for the HPA-1b polymorphism showed a significantly higher rate (slope) and greater extent (%) of adrenaline-induced aggregation than platelets not carrying the HPA-1b allele (P < 0.05). A greater extent of collagen-induced aggregation was also demonstrated in HPA-1ab platelets (P < 0.05). Inhibition of adrenaline-induced aggregation following incubation with aspirin was greater (P < 0.01) in HPA-1ab than in HPA-1aa platelets. Collagen-induced aggregation was slower in carriers of the HPA-5b allele than in HPA-5aa subjects (P < 0.05). Polymorphisms of the HPA-2 and HPA-3 systems were not associated with different aggregation responses to either adrenaline or collagen. These results support the clinical observation that polymorphism HPA-1b may predispose to increased platelet thrombogenicity and suggest that the presence of polymorphism HPA-5b might render the platelet less reactive to collagen.     

Gene frequencies of the human platelet antigen-3 in different populations.

Human platelet antigen (HPA) systems consist of more than 12 biallelic antigen polymorphisms in which a base pair substitution leads to change in an amino acid of a glycoprotein expressed on the platelet. HPA-3 is a HPA that is mentioned for possible induction of neonatal alloimmune thrombocytopenia, posttransfusion purpura, and platelet refractoriness. A summary is presented of previous reports on the gene frequencies of HPA-3 among different populations. The frequency of HPA-3a and -3b ranges from 0.50 to 0.61 and 0.38 to 0.50, respectively. A significant correlation between the population ethnicity and the gene frequencies was detected in this study. However, it is quite difficult to use HPA-3 gene as a gene marker to determine the similarity of gene population in different populations. In addition, the comparison of the heterogenicity of HPA-3 frequencies to another well-known HPA gene, HPA-1 gene demonstrates that there is a greater variation in HPA-3 frequencies than in the HPA-1 gene. There was no significant correlation between the incidence of autoimmune thrombocytopenia disorder and the HPA-3 gene polymorphism pattern.     

DNA-Based Typing of Human Platelet Antigen Systems by Polymerase Chain Reaction-Single-Strand Conformation Polymorphism Method

Polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) method has been established to discriminate genotypes for the human platelet antigen (HPA) systems HPA-1, HPA-2, HPA-3, HPA-4, and HPA-5. Gene fragments which contain polymorphic sequences corresponding to the HPA-1, HPA-2, HPA-3, HPA-4, and HPA-5 systems were PCR-amplified with specific primers. The amplified DNA was denatured and subjected to non-denaturing polyacrylamide gel electrophoresis followed by silver staining. The results obtained by the PCR-SSCP method were in good agreement with those of the allotypes determined by serological typing. Furthermore, the results agreed with those obtained by other DNA-based typing methods such as PCR-allele-specific restriction enzyme analysis and PCR-sequence-specific primer. These results indicate that PCR-SSCP is a simple and sensitive method for determining HPA genotypes and identifying unknown polymorphisms.     

DNA sequencing-based typing of HPA-1 to HPA-17w systems

Although several DNA-based human platelet antigens (HPA) typing techniques, such as PCR-SSP and PCR-SSO, have been established, the typing errors and the lack of interlaboratory reproducibility are still the issues of concerns. In the present study, polymerase chain reaction primers were designed for identification of all the phenotypically different HPA-1 to HPA-17w types by sequencing-based typing (SBT) method using genomic DNA samples. No discrepancies were observed between PCR-SSP typing and SBT typing in typing a panel of HPA-typed platelet donors that included all common HPA types and the rare HPA-1b, 2b, 3b, and 6bw homozygous donors.     

Polymorphism of the human platelet antigen-5 system is a risk factor for occlusive vascular complications in patients with sickle cell anemia

BACKGROUND: Polymorphisms of platelet membrane glycoproteins such as human platelet antigen (HPA)-1b, HPA-2b, the -5T/C Kozak sequence and C807T have been described as risk factors for vascular disease. Vaso-occlusion episodes are a common feature of sickle cell anaemia (SCA), leading to complications such as stroke, acute chest syndrome, avascular head femur necrosis and priapism. Complex interactions are involved in vaso-occlusion, and activated platelets may play an important role. These data raised the question of whether platelet polymorphisms could be implicated in occlusive vascular complications (OVC) of SCA. MATERIALS AND METHODS: In this study, 97 patients with SCA were analysed in two groups: 34 patients presenting with OVC (SCA-VC) and 63 without these complications (SCA-N). The distribution of the HPA-1, -2 and -5 systems, as well as C807T dimorphism and -5T/C Kozak sequence alleles, was evaluated using DNA-based methods. RESULTS: Patients of the SCA-VC group showed a higher frequency of the HPA-5b allele (0.324) compared with those of the SCA-N group (0.111) (chi2 = 13.19, P = 0.0002). None of the other polymorphisms, isolated or associated as haplotypes, demonstrated any correlation with the development of OVC in these patients. CONCLUSIONS: The findings of this study suggest that the HPA-5b allele is a genetic risk factor for the development of OVC in patients with SCA. This allele could be explored as a target for the development of new therapeutic approaches.     

Influence of human platelet antigen match on the success of stem cell transplantation after myeloablative conditioning

Mismatches between donor and recipient for human platelet antigens (HPA) may affect the success of transplantation due to: (a) serving as minor histocompa-tibility antigens and therefore render recipients at risk for graft-versus-host disease (GvHD), (b) inhibition of thrombopoiesis due to platelet antibodies. We therefore evaluated the occurrence of GvHD and need of platelet support by prospective analysis of donor-recipient pairs (n=53) for HPA-1, -2, -3, and -5 allotypes and screening for platelet antibodies prior to transplantation and in weekly intervals until day 100 after transplantation. Neither the incidence of GvHD nor the onset of thrombopoiesis, nor the CCI after platelet transfusions, nor the frequency of platelet transfusions was affected by HPA mismatches. Settings of homozygous donors vs heterozygous recipients or homozygous recipients vs heterozygous donors were not associated with any adverse effects on the outcome of the transplantation. Thus, the HPA-match does not affect the success of transplantation.     

PCR直接测序法检测人类血小板抗原HPA-1～-17bw基因型的探讨

目的：建立人类血小板抗原（Human platelet antigen,HPA）基因系统PCR扩增产物直接测序的方法并对序列进行分析。方法：PCR扩增HPA-1～-17bw基因片段,将PCR扩增产物纯化后直接进行DNA序列测定。结果：聚合酶链式反应-序列特异性引物（PCR-SSP）和直接测序法（SBT）对HPA已知型的血小板供者常见和罕见的HPA-1bb、HPA-2bb和HPA-6bb纯合子等供者的分型结果是一致的。结论：成功建立人类血小板抗原HPA1-17bw基因系统的PCR直接测序方法,能够准确可靠地鉴定HPA多态性,并能进一步应用于血小板免疫学和人类遗传学研究。