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Biomedical subjects

D Stroncek

Publications and source records attributed to D Stroncek.

At least 19 recordsLinked to original sources
PubMed2003

Assessment of the relative number of copies of the gene encoding human neutrophil antigen-2a(HNA-2a), CD177, and a homologous pseudogene by quantitative real-time PCR.

Human neutrophil antigen-2a (HNA-2a; NB1) is located on the 58-64 kD NB1 glycoprotein (GP) and is encoded by the gene CD177. Searches of human genome databases have revealed that a pseudogene highly homologous to exons 4-9 of CD177 is located adjacent to CD177 on chromosome 19. The purpose of this study was to document the presence of the pseudogene and determine whether the polymorphic expression of NB1 GP is due to CD177 gene deletions and duplications. Genomic DNA was isolated from leukocytes of 12 subjects. The number of copies of exon 2 of CD177, an exon that is unique to this gene, and the number of copies of exon 9, an exon that is found in both CD177 and the pseudogene, was assessed with quantitative real-time PCR. The ratio of the number of copies of sequences homologous to CD177 exon 9 to the number of copies of exon 2 was 1.5 or greater in 7 of the 12 subjects, suggesting that both CD177 and the homologous pseudogene were present. The ratio of exon 9 to exon 2 in the other 5 subjects ranged from 1 to 1.25, suggesting that the pseudogene was not present in these subjects. However, results of assays were variable and we could not exclude the possibility that all subjects carried the pseudogene. These studies confirmed the presence of the pseudogene homologous to CD177, but quantitative real-time PCR was not precise enough to detect CD177 duplications or deletions.

Journal Article↗
PubMed2002

In vitro RBC exposure to Plasmodium falciparum has no effect on RBC antigen expression.

Severe malarial anaemia is a leading cause of death in African children younger than 3 years of age who are infected with Plasmodium falciparum. The pathogenesis of this anaemia is not understood. The purpose of this study was to determine if P. falciparum induces changes in RBC membranes that contribute to the immune destruction of RBCs. RBCs were collected from healthy subjects and tested using standard haemagglutination assays for 45 antigens representing 21 blood group systems/collections before and after exposure to P. falciparum, strain FVO. Lectins were used to determine whether crypt or neoantigens were expressed on the RBC membrane. Polybrene was used to detect changes in sialic acid. RBCs were cultured in vitro with and without the parasite, and blinded serologic studies were completed. CD35 (complement receptor 1), CD55 (decay-accelerating factor), CD59 (membrane inhibitor of reactive lysis) and CD47 (integrin-associated protein) flow cytometric assays were compared for infected and uninfected RBCs. The percentage of parasitaemia was determined using Giemsa-stained thin blood films. Two (Ch, Lub) of the 45 antigens had differing strengths of agglutination between infected and uninfected RBCs, but these differences were resolved with a second source of antisera. Forty-three antigens showed no significant differences in the strength of agglutination between the infected and uninfected RBCs. Lectin and polybrene testing showed no differences. CD35, CD55, CD59 and CD47 levels showed no significant differences. P. falciparum does not appear to alter the expression of classified immunogenic antigens on the RBC membrane in this in vitro system. The pathogenesis of the haemolytic episode that occurs in these children remains unclear.

Animals↗
PubMed2002

A novel method using formamide for the elution of antibodies from erythrocytes.

BACKGROUND AND OBJECTIVES: Accurate identification of antibodies that sensitize red blood cells (RBCs) involves dissociating them from RBCs using an in vitro elution method that does not alter their antigen-binding properties, and analysis of the eluates against a panel of RBCs. MATERIALS AND METHODS: A method was developed that allowed efficient RBC antibody elution. Human polyclonal anti-D was used to sensitize Rh-positive RBCs, and known antigen-antibody disruptive reagents were tested using these RBCs. The best reagent conditions were optimized. Eluates made were tested and compared to results obtained with a glycine-acid-based commercial elution kit to determine efficacy. Patient samples that were positive with direct antiglobulin tests (DATs), and in vitro commercial antisera-sensitized RBCs representing clinically significant antibodies, were used for evaluating the new method. RESULTS: The formamide method was efficient at removing antibodies from RBCs. The patient samples with a positive DAT had antibodies recovered with the same specificity when compared to the acid-based technique. The length of preparation time was similar for both formamide and acid-based methods. Results of testing the eluates made from reagent RBCs sensitized with commercial antisera were distinct with antigen-positive and -negative erythrocytes. CONCLUSIONS: The formamide method compares well with acid techniques and may be an alternative choice of elution method.

Agglutination Tests↗
PubMed2001

Molecular basis of the neutrophil glycoprotein NB1 (CD177) involved in the pathogenesis of immune neutropenias and transfusion reactions.

The human granulocyte alloantigen NB1, recently clustered as CD177, is heterogenously expressed on neutrophils of 88-97% of healthy individuals. Since its molecular nature has remained unknown, we isolated NB1 glycoprotein from granulocyte lysate by immunoaffinity chromatography. MALDI-TOF mass spectrometry identified a 50,556 Da glycoprotein which was reduced to 43,069 Da after removal of N-linked carbohydrates. Following N-terminal amino acid sequencing and NB1-specific primer construction, rapid amplification of cDNA ends PCR yielded a 1,614-bp cDNA for NB1. COS-7 cells transfected with the cDNA expressed immunoreactive NB1 glycoprotein. A 1,311-bp sequence was identified to be the entire coding region. The 5' and 3' untranslated regions consist of 27 bp and 276 bp, respectively. The open reading frame codes for 437 amino acids of which the first 21 form the signal peptide. The remaining 416 residues form a N-terminal extracellular protein with two cysteine-rich domains, three N-linked glycosylation sites and short transmembrane and cytoplasmic segments including a glycosyl-phosphatidylinositol attachment (omega) site. Database searches revealed homology to Ly-6 (uPAR) domain, suggesting that NB1 belongs to urokinase plasminogen activator receptor/CD59/Ly-6 snake toxin superfamily.

Amino Acid Sequence↗
PubMed2000

Drug-induced hemolysis: cefotetan-dependent hemolytic anemia mimicking an acute intravascular immune transfusion reaction.

Numerous cases of drug-induced hemolytic anemia have been described in patients treated with penicillin or cephalosporin. Second and third generation cephalosporins are more commonly implicated in hemolytic reactions than first generation cephalosporins. We report a case of severe cefotetan-induced hemolytic anemia in a previously healthy 46-year-old woman undergoing an elective hysterectomy. The patient received 2 g of intravenous cefotetan intraoperatively and subsequently at 12 and 24 h post-operatively. She complained of diarrhea and fever on the third post-operative day and was seen in her gynecologist's office on the fifth post-operative day (hemoglobin = 10.5 g/dL). On the seventh post-operative day, she complained of fever and soreness around the suprapubic catheter site and was given a prescription for 500 mg oral cephalexin four times a day. The next day she was seen in the gynecologist's office and reported feeling better. Ten days after the operation her fatigue worsened and her hemoglobin was 4.8 g/dL. She was transfused with 3 units of packed red blood cells (PRBC) and was given 1 g of cefotetan intravenously. During the transfusion of the second unit of PRBC nursing staff observed gross hemoglobinuria and she subsequently developed acute renal failure. Laboratory chemistry parameters were consistent with severe acute hemolysis. The patient's direct antiglobulin test was reactive and her serum reacted with cefotetan-coated red blood cells (RBCs) and serum plus soluble cefotetan reacted with untreated RBCs. The titration endpoint of the serum against cefotetan-coated RBCs was 40,960, while the serum plus soluble cefotetan against uncoated RBCs was 2,560. This case of severe cefotetan-induced hemolysis was complicated by an acute hemolytic event that occurred during the transfusion of PRBC. Clinical and transfusion service staff must consider drug-induced hemolysis in the differential diagnosis of acute anemia.

Anemia, Hemolytic↗
PubMed2000

Variations in genes encoding neutrophil antigens NA1 and NA2.

BACKGROUND: Neutrophil-specific antigens NA1 and NA2 are located on Fcgamma receptor IIIb (FcgammaRIIIb). NA1 and NA2 forms of FcgammaRIIIb differ by four amino acids and the corresponding genes by five nucleotides. Variations in NA gene frequencies are encountered among ethnic groups. Altered forms of the genes are expected among individuals. STUDY DESIGN AND METHODS: RFLPs associated with four recognition sites were used to determine NA genotypes of 232 individuals. When atypical NA genotypes were identified, FcgammaRIIIB and FcgammaRIIIA regions were sequenced. RESULTS: NA1 FcgammaRIIIB frequency in 100 Japanese (0.66) was greater than that in 53 African Americans (blacks) (0.40; p<0.01) and 79 whites (0.32; p<0.001). Sequencing of atypical FcgammaRIIIB in 16 people confirmed that four blacks had G-->A substitutions at 227; 7 blacks had A-->G substitutions at 277; and 1 Japanese person had C-->G at 141 and G-->T at 227. A at 227 and G at 277 represent expected nts of NA1 FcgammaRIIIB. One black had an NA1 FcgammaRIIIB with a G-->A substitution at 349; A is normally found in NA2 FcgammaRIIIB at 349. Sequencing atypical FcgammaRIIIA in three persons revealed that two blacks had G-->A substitutions at 277 plus C-->A substitutions at 266 and 1 white had previously described T-->G at 230. Two blacks with atypical NA2 FcgammaRIIIB had T-->G FcgammaRIIIA at 230. One black was NA(null). CONCLUSION: NA2 FcgammaRIIIB is more polymorphic in blacks than in whites or Japanese persons. Chimeric FcgammaRIIIB alleles are most similar to NA2 FcgammaRIIIB. One alternate allele of NA1 (NA1*02) and four alternate alleles of NA2 (NA2*02, NA2*03, NA2*04, and NA2*05) are described.

Alleles↗
PubMed2000

Variations in the expression of granulocyte antigen NB1.

BACKGROUND: Between 87 and 97 percent of whites express NB1 alloantigen on some but not all of their granulocytes. The expression of NB1 has not been compared among large groups of adults of different sexes, ages, and ethnic groups. Previous testing of whites suggests that the expression of NB1 is variable. STUDY DESIGN AND METHODS: Serologic testing of granulocytes from 224 persons with two examples of MoAb to NB1 (1B5 and 7D8) was performed to distinguish phenotypic differences among age, sex, and ethnic groups and differences in reactivity to MoAbs. The donors were from 17 to 82 years of age, and 87 were female. They were from four ethnic backgrounds: 54 were African American (black), 10 were Asian, 9 Hispanic, and 152 white. Granulocytes were tested by flow cytometry. Parallel testing with MoAbs to CD16, CD11b, and CD45 served as controls. The size of the granulocyte population reacting with 1B5 and 7D8 and the respective mean, median, and peak cell fluorescence intensities were analyzed. RESULTS: The expression of 7D8 and 1B5 was greater on granulocytes from female donors. The expression of 7D8 fell in older women but not in men. There were no differences among the four racial groups in either the frequency of NB1 as determined by 1B5 or 7D8 or in the size of the population of granulocytes reacting with either antibody. When the fluorescence intensities of the antibody reactions were compared among groups, there were no differences in reactivity with 1B5. However, reactions with 7D8 were all greater in blacks. Comparison of the size of the antigen-positive granulocyte population, as determined by antibody reactivity, showed that only 30 donors differed by more than 10 percent. These discordant results were more likely to occur in whites than in blacks (18% vs. 4%, p<0.02). CONCLUSIONS: NB1 is composed of at least two epitopes as determined by serologic studies. The expression of both antigens is greater in females. The 7D8-reactive epitope appears to be more prevalent or more accessible on granulocytes of blacks. Variations in the expression of NB1 are more likely to occur in whites. The biochemical and molecular basis of these variations are not known.

Adolescent↗
PubMed1999

Effects of granulocyte-colony-stimulating factor on potential normal granulocyte donors.

BACKGROUND: The use of granulocyte-colony-stimulating factor (G-CSF) to increase the granulocyte count and the yield from leukapheresis in normal donors is leading to renewed interest in granulocyte transfusion. Therefore, it is important to understand the side effects of G-CSF. STUDY DESIGN AND METHODS: We studied the effect of G-CSF on peripheral blood counts and recorded the side effects experienced 24 hours after an injection of G-CSF in normal subjects donating peripheral blood progenitor cells for research. RESULTS: Following administration of G-CSF to 261 donors, the neutrophil count increased to 20.6 to 24.5 x 10(9) per microL depending on the dose of G-CSF. This represented a 6.2 to 7.4-fold increase over the neutrophil count before G-CSF administration. Of all donors, 69 percent experienced one or more side effects. The most common effects were: muscle and bone pain, headache, fatigue, and nausea. There was a relationship between the dose of G-CSF and the likelihood of experiencing a side effect. Most side effects were mild, but about 75 percent of donors took analgesics because of them. CONCLUSIONS: In a granulocyte donation program involving G-CSF stimulation, about two-thirds of donors would experience one or more side effects, but these would usually be mild and well tolerated.

Adolescent↗
PubMed1999

High-resolution HLA-A*0201 subtyping using directed heteroduplex analysis.

HLA-A02* has become an important target for cytotoxic T lymphocyte-based immunotherapy reflecting the high prevalence of this allele in patient populations. There are at least 26 different A*02 alleles, and their subtype specificity has significant functional implications for T-cell-mediated recognition of immunologic targets. We have developed a novel method for HLA-A*02 allelic screening using directed heteroduplex analysis (DHDA). DNA samples from Epstein-Barr virus (EBV)-transformed B lymphoblastoid cell lines (EBV-B) representing 10 different HLA-A*02 alleles (0201, 0202, 0204, 0205, 0206, 0208, 0210, 0211, 0216, 0217) were prepared. In addition, DNA was prepared from 81 individuals representing a wide variety of A*02 subtypes previously determined by sequence specific primer (SSP) polymerase chain reaction (PCR) including individuals heterozygous for two A*02 specificities. Probes and samples were generated by PCR amplification using HLA-A*02 specific primers encompassing exons 2 and 3, where most of the functionally significant allelic polymorphism is clustered. DHDA was performed by generating heteroduplex molecules composed of a fluorescein-labeled allelic probe sequence and an unlabeled allelic PCR product. Gel retardation was consistent for allele-probe combinations. We were able to identify several A*02 alleles prepared from EBV-B cell lines that, when used as probes, had very impressive specificity and sensitivity. Combinations of two probes were identified (0205 + 0211 and 0208 + 0211) that allowed differentiation of A*0201 alleles from all other A*02 alleles tested. All samples typed by probe combinations had DHDA typing and SSP typing confirmed by DNA sequencing. This study expands the molecular typing repertoire available to the modern HLA laboratory, and shows that DHDA has significant promise as a reliable screening method for HLA A*02 subtyping.

B-Lymphocytes↗
PubMed1998

Mobilization and homing of peripheral blood progenitors is related to reversible downregulation of alpha4 beta1 integrin expression and function.

Despite the wide use of mobilized peripheral blood (PB) progenitor cells (PBPC) for clinical transplantation the mechanism(s) underlying their mobilization and subsequent engraftment are still unknown. We compared the adhesive phenotype of CD34(+) colony-forming cells (CFC) in bone marrow (BM) and PB of normal donors before and after administration of granulocyte colony-stimulating factor (G-CSF) for 5 d. G-CSF-mobilized PB CFC cells adhered significantly less to BM stroma, fibronectin, and to the alpha4 beta1 binding fibronectin peptide, CS1, because of decreased expression of the alpha4 integrin. Since incubation of BM CD34(+) cells for 4 d with G-CSF at concentrations found in serum of G-CSF- treated individuals did not affect alpha4-dependent adhesion, G-CSF may not be directly responsible for the decreased alpha4-mediated adhesion of PB CFC. Culture of G-CSF-mobilized PB CD34(+) cells with cytokines at concentrations found in BM stromal cultures upregulated alpha4 expression and restored adhesion of mobilized PB CFC to stroma, fibronectin, and CS1. Adhesion of cultured, mobilized PB CFC to stroma and CS1 could not be further upregulated by the beta1 activating antibody, 8A2. This indicates acquisition of a maximally activated alpha4 beta1 integrin once PB CFC have been removed from the in vivo mobilizing milieu. Thus, decreased alpha4 expression on CD34(+) CFC in PB may be responsible for the aberrant circulation of mobilized PB CD34(+) cells. Reexpression of a maximally activated alpha4 beta1 integrin on mobilized PB CFC removed from the mobilizing in vivo milieu may contribute to the early engraftment of mobilized PBPC.

Antigens, CD34↗
PubMed1998

HLA allele distribution distinguishes sporadic inclusion body myositis from hereditary inclusion body myopathies.

We studied the HLA class II associations in patients with sporadic inclusion body myositis (s-IBM) and hereditary inclusion body myopathies (h-IBM) and attempted to distinguish these myopathies on the basis of HLA allele assignments. Forty-five patients, 30 with s-IBM and 15 with h-IBM, underwent HLA class II allele-specific typing using polymerase chain reaction sequence-specific primers for 71 alleles contained in the DRbeta1, DRbeta3-5, and DQbeta1 loci. In s-IBM, we found a high (up to 77%) frequency of DRbeta1*0301, DRbeta3*0101 (or DRbeta3*0202) and DQbeta1*0201 alleles. No significant association with alleles in the DR and DQ haplotypes was found among the 15 h-IBM patients. The strong association of prominent alleles with s-IBM, but not h-IBM, suggests that s-IBM is a distinct disorder with an immunogenetic background that differs from h-IBM.

Aged↗
PubMed1998

Mobilization and transduction of peripheral blood progenitor cells in patients with mucopolysaccharidosis I.

Mucopolysaccharidosis type I (MPS I) results from a deficiency of alpha-L-iduronidase enzyme (IDUA), an enzyme responsible for the catabolism of glycosaminoglycans. Genetically modified progenitor cells may permit a therapeutic effect similar to that obtained from allogeneic BMT without the associated risks. To that end, CD34+ peripheral blood hematopoietic progenitor cells from patients with MPS I were mobilized using G-CSF, collected by apheresis, and enriched using avidin-biotin separation techniques. These cells were cultured in a hollow fiber bioreactor and transduced with a retroviral vector (LP1CD) containing the cDNA for human IDUA and a murine dihydrofolate reductase (DHFR) enzyme. Approximately 4%-16% of the colonies expressed methotrexate drug resistance. Expression of the IDUA enzyme in the progenitor cells was initially high and declined after approximately 10 days of culture. These results indicate that PBPC from patients with MPS I can be mobilized, isolated, enriched, and transduced with a therapeutic gene.

Adult↗