How clinicians can minimize transfusion-related adverse events?

OBJECTIVES: Transfusion-related adverse events (TRAE) can contribute to patient morbidity and mortality. In this brief narrative review, the strategies that clinicians can apply at the bedside to avoid TRAE are discussed. METHODS: Strategies to avoid the following five types of TRAE were reviewed: transfusion-associated circulatory overload (TACO), transfusion-related acute lung injury (TRALI), transfusion-associated hypothermia (TAH), transfusion-related allergic reactions (TRAR) and acute haemolytic transfusion reactions (AHTR). RESULTS: Minimizing exposure to blood components is fundamental to TRAE avoidance. Pre-transfusion assessment can identify patients at risk of TACO, TRAR and TAH, and avoidance steps implemented. Preventive strategies for TACO include lower transfusion rate, 'one unit at a time' transfusion policy and possibly diuretic medication. Patients with past history of TRAR should preferably be given plasma-free blood components; anti-histamine medication prior to transfusion could be considered. TAH is common in the massive transfusion setting, particularly trauma patients. Warming of patients are key strategies to avoid TAH. Identification of patients at risk of TRALI is more opaque; however, any measures that limit pulmonary inflammation prior to transfusion may decrease the risk of TRALI. Causes of AHTR are commonly due to human error and failure to apply rigorous cross-checks of patient and issued RBC component blood groups. CONCLUSIONS: Beneficial strategies to avoid TRAE include judicious use of blood components, identification of high-risk patients, adherence to recommended clinical processes and awareness of TRAE pathophysiology. More evidence is warranted to better guide clinicians in the prevention of TRAE.

Longer storage of red blood cells is associated with increased in vitro erythrophagocytosis.

BACKGROUND AND OBJECTIVES: Refrigerated storage of red blood cells (RBCs) induces numerous changes that may target the cells for erythrophagocytosis following transfusion. The influence of storage upon the phagocytosis of unseparated and fractionated young and old stored RBCs was investigated using two in vitro quantitative phagocytosis assays. MATERIALS AND METHODS: Leucocyte-depleted RBC units were sampled at day 1 or 42 of storage. Young and old RBCs were fractionated at day 1 by density centrifugation and stored in paediatric packs for up to 42 days. RBCs were labelled with the fluorescent dye PKH26 and incubated with the human monocytic cell line THP-1. Erythrophagocytosis was quantified by flow cytometry and plate fluorometric assays. RESULTS: A higher proportion of THP-1 cells phagocytosed RBCs stored for 42 days compared with 1 day (41% and 24% respectively; P<0·0001). This was associated with an increased mean number of RBCs phagocytosed per THP-1 cell (5·2±0·6 and 3·3±0·2 respectively; P<0·002). Erythrophagocytosis of fractionated young and old RBCs increased with longer storage duration up to 28 days (P<0·05). However, no significant differences were observed between erythrophagocytosis of young and old RBCs. CONCLUSION: The susceptibility of stored RBCs to erythrophagocytosis significantly increased with longer storage time of the RBC units. Storage duration of RBCs had a greater influence on in vitro erythrophagocytosis than the chronological age of the RBCs at donation.

Apoptotic lymphocytes and CD34+ cells in cryopreserved cord blood detected by the fluorescent vital dye SYTO 16 and correlation with loss of L-selectin (CD62L) expression.

Discrimination between live and apoptotic cells is important for accurate determination of viable CD34(+) cells in hematopoietic stem cell transplant products. SYTO16 is a sensitive fluorescent dye for discriminating live from apoptotic leukocytes. The incidence of apoptotic leukocytes in paired samples of fresh and cryopreserved-thawed cord blood (CB) was determined by the SYTO16/7-AAD flow cytometric assay. Cell migration and expression of the cell homing molecule L-selectin (CD62L) was determined in relation to SYTO16 staining. SYTO16 detected significant proportions of apoptotic lymphocytes and CD34(+) cells in fresh and thawed CB buffy-coat samples that were not detected by 7-AAD. Compared to fresh CB, the proportion of apoptotic lymphocytes and CD34(+) cells significantly increased following thawing. Significantly higher proportions of live SYTO16(bright) lymphocytes and CD34(+) cells were found in the migrated cell population compared to the non-migrated population. Significantly fewer lymphocytes and CD34(+) cells expressed CD62L following thawing. Absence of CD62L expression was strongly correlated with apoptotic/SYTO16(dim) lymphocytes and CD34(+) cells. Cryopreserved-thawed CB contains significant proportions of apoptotic lymphocytes and CD34(+) cells that are not detected by 7-AAD. SYTO16 offers a sensitive method for discrimination of live from apoptotic leukocytes and assists in accurate assessment of CB quality and suitability for use in clinical transplantation.

Supernatant from stored red blood cell primes inflammatory cells: influence of prestorage white cell reduction.

BACKGROUND: The contribution of RBC transfusion to adverse patient outcomes is controversial. There is conflicting clinical data and limited biologic data that provide an underpinning biologic rationale for any adverse impacts from RBC transfusion. This study used in-vitro measures of PMN stimulation to determine the ability of supernatant from RBCs to stimulate allogeneic WBCs and to determine the influence of residual donor WBCs and storage time on the proinflammatory potential of RBCs. STUDY DESIGN AND METHODS: Three types of RBCs were assessed: standard non-WBC-reduced RBCs (S-RBCs), buffy coat-poor RBCs (BCP-RBCs), and prestorage WBC-filtered RBC (LF-RBCs). Supernatant was collected weekly up to Day 42 of storage. PMN priming by supernatant from RBCs was determined by three methods: induction of CD11b expression on PMNs, induction of IL-8 release from PMNs, and the chemotactic effect of supernatant on PMNs. RESULTS: Supernatant from S-RBCs induced the expression of CD11b on PMNs, primed PMNs to release IL-8, and was chemotactic for PMNs. The magnitude of this PMN-priming progressively amplified with storage time. In contrast, supernatant from BCP-RBCs or LF-RBCs did not significantly prime PMNs. The PMN-priming effect of supernatant from RBCs correlated more closely with the level of MNCs in the RBCs than PMN content. CONCLUSION: Supernatant from stored S-RBCs prime unstimulated allogeneic PMNs in vitro. Prestorage buffy-coat WBC reduction was as effective as WBC depletion in abrogating this proinflammatory response elicited by supernatants from RBCs. The clinical consequences, if any, of these findings for transfusion recipients are unknown.

Microbial screening of UC blood units by an automated culture system: effect of delayed testing on bacterial detection.

BACKGROUND: Microbial screening is a mandatory test for banked UC blood (UCB) to comply with the code of good manufacturing practice (GMP). Cord blood banks (CBBs) are not always closely located to a GMP-licensed microbiology laboratory, resulting in time delays for transport of specimens prior to microbiological testing. This study investigated the influence of >/=24 h delays in initiating automated microbial screening on the detection of bacteria in UCB, by analysis of specimens deliberately spiked with bacteria and the recovery of bacteria from cryopreserved spiked-UCB. MATERIALS AND METHODS: UCB was processed according to standard CBB procedures and spiked with Staphylococcus epidermidis or Escherichia coli [2-2000 colony forming units (CFU)/mL]. Spiked-UCB (0.5 mL) was (1) held at room temperature (RT) and inoculated into pediatric BacT/Alert bottles (bioMérieux) at Days 1, 4 and 7 (delayed inoculation); and (2) inoculated directly (Day 0) into replicate BacT/Alert bottles and held at RT for 1, 4 or 7 days before loading onto the BacT/ALERT system (delayed loading). Spiked-UCB samples were cryopreserved. Bacterial counts were quantitated on horse blood agar plates. RESULTS: Bacterial growth in UCB spiked with a single bacterium was capable of detection by the BacT/ALERT system. S. epidermidis grew in all conditions of delayed testing (ie. delayed inoculation and delayed loading). E. coli failed to grow under conditions of delayed inoculation but grew at all time points of delayed loading. S. epidermidis and E. coli were recovered from cryopreserved spiked-UCB. DISCUSSION: Inoculation of culture bottles as soon as possible after sample preparation is preferable. Bacteria can maintain viability in BacT/ALERT bottles inoculated and held at RT for up to 7 days prior to automated culture testing. Bacteria can be successfully recovered from cryopreserved UCB.

Identification and characterization of a novel family of mammalian ependymin-related proteins (MERPs) in hematopoietic, nonhematopoietic, and malignant tissues.

Evidence is presented for a family of mammalian homologs of ependymin, which we have termed the mammalian ependymin-related proteins (MERPs). Ependymins are secreted glycoproteins that form the major component of the cerebrospinal fluid in many teleost fish. We have cloned the entire coding region of human MERP-1 and mapped the gene to chromosome 7p14.1 by fluorescence in situ hybridization. In addition, three human MERP pseudogenes were identified on chromosomes 8, 16, and X. We have also cloned the mouse MERP-1 homolog and an additional family member, mouse MERP-2. Then, using bioinformatics, the mouse MERP-2 gene was localized to chromosome 13, and we identified the monkey MERP-1 homolog and frog ependymin-related protein (ERP). Despite relatively low amino acid sequence conservation between piscine ependymins, toad ERP, and MERPs, several amino acids (including four key cysteine residues) are strictly conserved, and the hydropathy profiles are remarkably alike, suggesting the possibilities of similar protein conformation and function. As with fish ependymins, frog ERP and MERPs contain a signal peptide typical of secreted proteins. The MERPs were found to be expressed at high levels in several hematopoietic cell lines and in nonhematopoietic tissues such as brain, heart, and skeletal muscle, as well as several malignant tissues and malignant cell lines. These findings suggest that MERPs have several potential roles in a range of cells and tissues.

Enumeration of CD34+ cells in cord blood: a variation on a single-platform flow cytometric method based on the ISHAGE gating strategy.

Single-platform flow cytometric absolute cell counting protocols provide increased robustness for CD34+ cell enumeration by limiting potential sources of imprecision. However, samples with any cellular fragmentation or debris, such as cord blood samples, provide challenges for these assays. We describe a simple, robust absolute CD34+ cell counting protocol, suitable for cord blood, using TRUCOUNT absolute count tubes (BD Biosciences, San Jose, CA) and a modified ISHAGE (International Society for Hematotherapy and Graft Engineering) gating strategy. An advantage of TRUCOUNT tubes is that each tube is supplied with a known number of lyophilized fluorescent beads. The method includes no-wash fixative-free ammonium chloride red blood cell lysis and the viability dye, 7-amino actinomycin D, to exclude dead cells. The threshold was set on CD45 expression in the FL1 channel and an exclusion gate in the forward scatter channel reduced debris. No manual adjustment of the gating regions was required, even for samples in less than optimal condition. Comparison of the TRUCOUNT-ISHAGE protocol with the original dual-platform ISHAGE assay (n = 30) and the single-platform ISHAGE protocol using Flow-Count Fluorospheres (Beckman Coulter, Fullerton, CA; n = 22) showed high correlation (R(2) = 0.949 and 0.989, respectively) and no significant difference or bias for samples ranging from 22 to 600 CD34+ cells per microliter. Results are presented that demonstrate the detrimental effect of a fixative-containing lysis reagent when used in a lyse-and-wash procedure. The TRUCOUNT-ISHAGE protocol combines the attributes of TRUCOUNT tubes and the ISHAGE gating strategy to provide a single-platform protocol capable of achieving readily standardization of CD34+ cell enumeration.

The short tandem repeat locus VWF2 in Intron 40 of the von Willebrand factor gene consists of two polymorphic sub-loci.

This study describes the complex nucleotide sequence structure of the TCTA short tandem repeat (STR) locus, VWF2. Eight alleles of VWF2 were observed in a population of 116 unrelated Caucasian individuals. The alleles ranged in size from 150 to 178 base pairs (bp). Sequence analysis of the isolated alleles revealed two polymorphic regions that were named sub-loci VWF2-a and VWF2-b. VWF2-a is located at the 5' end of the conventional locus, whilst VWF2-b is located at the 3' end. The two sub-loci are joined by a 30-nucleotide non-polymorphic sequence which contains two additional TCTA motif repeats. A semi-nested polymerase chain reaction (PCR) was designed to amplify the VWF2-b region in conjunction with the standard VWF2 amplification. This new amplification method enabled a higher level of allele discrimination than could be achieved by assigning alleles according to size. A cohort of 99 unrelated individuals was tested with this method. VWF2-a expressed five different alleles ranging from zero motif repeats to four motif repeats, while VWF2-b alleles ranged from 8 to 14 motif repeats. Allelic configuration based on the VWF2-a and VWF2-b sub-alleles revealed 23 unique configurations out of a possible 31 for the original eight VWF2 alleles. In conclusion, the VWF2 is a highly polymorphic STR locus with potential application for forensic and parentage testing.

Serologic and molecular investigations of a chimera.

A chimeric individual possesses two or more genetically distinct cell populations. Although the chimerism may not be evident in all gene systems, various loci display greater numbers of alleles than genetically "normal" individuals. The proposita was referred for further laboratory investigation due to a mixed-field ABO blood group reaction following routine antenatal testing. Various molecular (HLA class II, ABO genotyping, and 10 short tandem repeat [STR] microsatellites) and serologic (HLA class I and red cell blood groups) typing techniques were employed to investigate a number of polymorphic loci located on different chromosomes. Chimerism was identified in 8 out of the 14 chromosomes tested: chromosome 1 (Duffy), 6 (HLA class I and II), 9 (ABO), 11 (HUMTH01), 12 (HUMPLA2A1), 15 (HUMFES/FPS), 18 (Kidd) and 21 (D21S11). The proposita was determined to be a probable dispermic chimera, based on the results of the serology and molecular studies.

Instability in the ATCT variable number tandem repeat locus VWF.VNTR I in intron 40 of von Willebrand factor gene.

The von Willebrand factor gene intron 40 variable number tandem repeat VWF.VNTR I exhibits 10 alleles making it highly polymorphic and useful for parentage and forensic testing, 45 unrelated families (210 meiotic events) were tested for VWF.VNTR I alleles. One spontaneous mutation was observed in a family member. Haplotype analysis demonstrated that this mutation was due to a gain of one motif repeat by a paternal allele. Sequence analysis confirmed the difference in the number of motif repeats between the proband and the alleles expressed by the parents. This instability emphasizes the importance of demonstrating exclusion in at least two separate loci in parentage testing.

Two novel alleles of the ATCT variable number tandem repeat locus VWF.VNTR I in intron 40 of the von Willebrand factor gene.

Two new alleles, allele 9 and allele 15, of the ATCT variable number tandem repeat locus, VWF.VNTR I, of intron 40 of the von Willebrand factor (VWF) gene are described. Both alleles occurred in low frequencies, being detected in only two and one of 285 random Australian Caucasians respectively. In all, 10 alleles were observed representing between six and 15 repeats of the ATCT motif. The allele frequency distribution in this Australian population was similar to other VWF.VNTR I population studies. The additional alleles described here for the VWF.VNTR I further enhance the usefulness of this VNTR locus in human identification work.

Perturbation in the ability of bone marrow stroma from patients with acute myeloid leukemia but not chronic myeloid leukemia to support normal early hematopoietic progenitor cells.

The ability of bone marrow (BM) stroma derived from patients with acute myeloid leukemia (AML) or chronic myeloid leukemia (CML) to support normal hematopoiesis was investigated using a two-stage long-term bone marrow culture (LTBMC) procedure. Of particular interest was whether leukemia-derived stroma were capable of supporting the very immature, uncommitted hematopoietic progenitor cells (HPC) which are considered to have a higher dependence and association with the BM stroma than the more mature committed HPC. Confluent stromal layers were recharged with selected populations of normal HPC enriched for the CD34+CD38- cells (immature, uncommitted HPC) or the CD34+CD38+ cells (mature, committed HPC). The weekly output of clonable granulocyte-macrophage progenitor cells (CFU-GM) was used as an indicator of the hematopoietic-supporting ability of the cultures. Stromal layers derived from 5/7 patients newly diagnosed with AML, showed significantly depressed ability to support the CD34+CD38- cells compared to stroma derived from normal donors. The supporting function of the AML-derived stroma for the more mature CD34+CD38+ cells was similar to that of the normal stroma (3/3 cases). Stromal layers derived from patients with chronic-phase CML showed normal or enhanced supporting function for the CD34+CD38- cells (5/6 cases), and likewise for the CD34+CD38+ cells (3/3 cases). This study revealed a selective defect in the ability of BM stroma from patients with AML to support the maturation of normal early uncommitted HPC, represented by the CD34+CD38- cells, whilst the ability to support the committed CD34+CD38+ cells was not affected. This suggests that the BM microenvironment may be implicated in the disease mechanism of AML. It does not, however, appear to be as clearly implicated in chronic-phase CML.

ABO genotyping by polymerase chain reaction-restriction fragment length polymorphism.

Genotyping enables the identification of both maternally and paternally derived alleles. A number of protocols have been described for the genotyping of the ABO blood group system. Generally, these methods have a number of disadvantages including the use of hazardous reagents, being technically demanding, and the excessive use of materials. In this study, a relatively simple polymerase chain reaction -restriction fragment length polymorphism (PCR-RFLP) method is described. Four different amplifications were used that were specific for nucleotides sites 261, 526, 703, and 796 to distinguish the A, B, O1 and O2 alleles. The ABO genotypes of 294 random individuals were determined and were found to completely correlate with the serologic phenotypes. The protocol is applicable for investigations of weak or nonexpression of ABO alleles, paternity determinations, and population analysis.

ABO genotyping-identification of O1, O1*, and O2 alleles using the polymerase chain reaction-sequence specific oligonucleotide (PCR-SSO) technique.

ABO polymorphism at the gene level has been investigated by molecular methods, predominantly sequencing and restriction fragment length polymorphism (RFLP). We describe the application of the polymerase chain reaction-sequence specific oligonucleotide (PCRSSO) method, which is considered to be more versatile for large sample numbers, compared with conventional ABO genotyping by PCR-RFLP. PCR-SSO, while maintaining accurate and reliable results, reduces costs and labor. A population of 155 random individuals was investigated for the three O alleles, O1, O1*, and O2. The allelic frequencies were 35 percent, 26 percent, and 5 percent, respectively. PCR-SSO results correlated completely with both serologic and PCRRFLP results.

Common expression of the multidrug resistance marker P-glycoprotein in B-cell chronic lymphocytic leukaemia and correlation with in vitro drug resistance.

The expression of P-glycoprotein (Pgp), which is associated with multidrug resistance (MDR), was investigated in 20 B-cell chronic lymphocytic leukaemia (B-CLL) patients by flow cytometry using two Pgp-specific monoclonal antibodies (mAb), MRK-16 which recognizes an extracellular epitope, and JSB-1 which recognizes an intracellular epitope. Sixteen (80%) patients were positive with MRK-16 whereas all patients were positive with JSB-1. The proportion of Pgp-positive lymphocytes from each patient sample varied from 2-94% for MRK-16 and 20-93% for JSB-1. There was no correlation between the level of positivity and disease stage or treatment history. In vitro drug resistance to vincristine (VCR) and doxorubicin (DOX) was determined by the colorimetric MTT assay. All patients were resistant to one or both drugs being consistent with the expression of Pgp. There was no correlation between the level of resistance and disease stage or drug treatment. We investigated the expression of Pgp in the normal counterpart of the B-CLL cells, CD5+CD19+ B-lymphocytes. A minor subpopulation (3%) of CD5+CD19+ lymphocytes isolated from normal controls expressed Pgp suggesting that these cells may be the potential precursors to the B-CLL cell. We conclude that Pgp expression and drug resistance are inherent characteristics of the B-CLL lymphocyte.

Several vascular complement inhibitors are present on human sperm.

We have previously reported that the complement inhibitor SP-40,40 is present in human seminal plasma. We also speculated that other inhibitors of the vascular complement system may be present within semen for the purpose of providing protection for sperm against complement within the male and/or female genital tract. In this study, we examined human seminal plasma and spermatozoa for the presence of several major complement regulatory proteins. We detected the presence of decay-accelerating factor (DAF) and CD59 and have confirmed the presence of Membrane Cofactor Protein (MCP) and SP-40,40 on human sperm. As an approach to the possible functional significance of these inhibitors on sperm membranes, the presence of two key complement components, C3 and C9, in seminal plasma was used as a criterion for an active complement system. We failed to detect C9 in seminal plasma and showed that its concentration was less than 5% of the level detected in blood plasma. C3 was also undetectable in seminal plasma; as assessed by Western transfer, its level was less than 0.3% of that in blood plasma. The low level or indeed the absence of key components of the complement system in seminal plasma--together with the finding that human sperm possess an extensive array of the vascular complement inhibitors, some of known physiologic significance--strongly suggests that their role on sperm is to protect sperm from complement lysis in the female rather than the male genital tract.

Tissue-specific and allelic expression of the complement regulator CD46 is controlled by alternative splicing.

CD46 (membrane cofactor protein) is a human cell surface glycoprotein with cofactor activity for factor I-mediated cleavage of complement components C3b and C4b. The CD46 protein from normal lymphocytes resolves on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as two major bands of 66 and 56 kDa. CD46 cDNA encodes four extracellular short consensus repeat domains, a Ser/Thr/Pro (STP)-rich region, a transmembrane region and a cytoplasmic tail. We now show that exquisite control of mRNA splicing is responsible for the heterogeneous expression of CD46 isoforms. Differential splicing of 5 exons generates at least 14 CD46 mRNA variants whose expression is stringently regulated by allelic, tissue-specific and malignancy-related factors, as: (a) leukemic cells and Epstein-Barr virus-transformed B cells preferentially incorporate the first of three STP exons (exon 7) into mRNA, and produce a larger CD46 isoform of 74 kDa, (b) an allelic difference in the proportion of 66- and 56-kDa CD46 isoforms on lymphocytes corresponds to the preferential inclusion or exclusion of the second STP exon (exon 8), (c) the third STP exon (exon 9) is specifically deleted in some placentae, (d) spermatozoa delete both exons 12 and 13, encoding a shorter transmembrane region and a unique cytoplasmic tail and (e) all tissues tested differentially splice exon 13, resulting in two alternative cytoplasmic tails. The distribution of the 14 alternatively spliced RNA transcripts correlated with the presence of protein isoforms of the predicted size, indicating that alternative splicing leads to heterogeneity of CD46 glycoproteins.