The cross-talk between miRNAs and JAK/STAT pathway in cutaneous T cell lymphoma: Emphasis on therapeutic opportunities

Mycosis Fungoides (MF) and Sézary Syndrome (SS) belong to a wide spectrum of T cell lymphoproliferative disorders collectively termed cutaneous T cell lymphomas (CTCL). CTCLs represent an archetype of heterogeneous and dynamically variable lymphoproliferative neoplasms typified by distinct clinical, histological, immunophenotypic, and genetic features. Owing to its complex dynamics, the pathogenesis of CTCL remains elusive. However, in recent years, progress in CTCL classification combined with next-generation sequencing analyses has broadened the genetic and epigenetic spectrum of clearly defined CTCL entities such as MF and SS. Several large-scale genome studies have identified the polygenic nature of CTCL and unveiled an idiosyncratic mutational landscape involving genetic aberrations, epigenetic alterations, cell cycle dysregulation, apoptosis, and the constitutive activation of T cell/NF-κB/JAK-STAT signaling pathways. In this review, we summarize the evolving insights on how the intrinsic epigenetic events driven by dysregulated miRNAs, including the oncogenic and tumor-suppressive miRNAs, influence the pathogenesis of MF and SS. We also focus on the interplay between the JAK/STAT pathway and miRNAs in CTCL as well as the significance of the miRNA/STAT axis as a relevant pathogenetic mechanism underlying CTCL initiation and progression. Based on these biologic insights, the current status and recent progress on novel therapies with a strong biological rationale, including miRNA-targeted molecules and JAK/STAT-targeted therapy for CTCL management, are discussed.

Beyond Viral Infections: The Multifaceted Roles of Human Papillomavirus and Epstein-Barr Virus in Shaping the Tumor Microenvironment

The tumor microenvironment (TME) exerts a profound influence on the oncogenesis and progression of various cancers, notably those instigated by the human papillomavirus (HPV) and the Epstein-Barr virus (EBV). The etiology of HPV and EBV-associated malignancies is rooted in intricate interactions that intertwine viral infections, genetic predispositions, and distinct TME dynamics. These interactions foster a milieu that can either support or hinder tumorigenic progression. Gaining in-depth knowledge of the TME's unique features, including its cellular composition, cytokine profiles, and metabolic alterations specific to HPV and EBV-associated cancers, is fundamental to innovating more efficacious therapeutic strategies. This review delineates the intricate roles of HPV and EBV in shaping the TME and expounds upon the unique TME characteristics specific to HPV and EBV-driven cancers. Additionally, we spotlight innovative approaches to remodel the TME, aiming to augment therapeutic efficacy in combatting HPV and EBV-associated neoplasms.

Embelin inhibits viability of cutaneous T cell lymphoma cell lines HuT78 and H9 by targeting inhibitors of apoptosis

Cutaneous T cell lymphoma (CTCL) is a varied group of neoplasms that affects the skin. Acquired resistance against chemotherapeutic drugs and associated toxic side effects are limitations that warrant search for novel drugs against CTCL. Embelin (EMB) is a naturally occurring benzoquinone derivative that has gained attention owing to its anticancer pharmacological actions and nontoxic nature. We assessed the anticancer activity of EMB against CTCL cell lines, HuT78, and H9. EMB inhibited viability of CTCL cells in a dose-dependent manner. EMB activated extrinsic and intrinsic pathways of apoptosis as shown by the activation of initiator and executioner caspases. EMB-induced apoptosis also involved suppression of inhibitors of apoptosis, XIAP, cIAP1, and cIAP2. PARP cleavage and upregulation of pH2AX indicated DNA damage induced by EMB. In conclusion, we characterized a novel apoptosis-inducing activity of EMB against CTCL cells, implicating EMB as a potential therapeutic agent against CTCL.

In vitro evaluation of Neosetophomone B inducing apoptosis in cutaneous T cell lymphoma by targeting the FOXM1 signaling pathway

BACKGROUND

Cutaneous T cell lymphoma (CTCL) is a T cell-derived non-Hodgkin lymphoma primarily affecting the skin, with treatment posing a significant challenge and low survival rates.

OBJECTIVE

In this study, we investigated the anti-cancer potential of Neosetophomone B (NSP-B), a fungal-derived secondary metabolite, on CTCL cell lines H9 and HH.

METHODS

Cell viability was measured using Cell counting Kit-8 (CCK8) assays. Apoptosis was measured by annexin V/PI dual staining. Immunoblotting was performed to examine the expression of proteins. Applied Biosystems' high-resolution Human Transcriptome Array 2.0 was used to examine gene expression.

RESULTS

NSP-B induced apoptosis in CTCL cells by activating mitochondrial signaling pathways and caspases. We observed downregulated expression of BUB1B, Aurora Kinases A and B, cyclin-dependent kinases (CDKs) 4 and 6, and polo-like kinase 1 (PLK1) in NSP-B treated cells, which was further corroborated by Western blot analysis. Notably, higher expression levels of these genes showed reduced overall and progression-free survival in the CTCL patient cohort. FOXM1 and BUB1B expression exhibited a dose-dependent reduction in NSP-B-treated CTCL cells.FOXM1 silencing decreased cell viability and increased apoptosis via BUB1B downregulation. Moreover, NSP-B suppressed FOXM1-regulated genes, such as Aurora Kinases A and B, CDKs 4 and 6, and PLK1. The combined treatment of Bortezomib and NSP-B showed greater efficacy in reducing CTCL cell viability and promoting apoptosis compared to either treatment alone.

CONCLUSION

Our findings suggest that targeting the FOXM1 pathway may provide a promising therapeutic strategy for CTCL management, with NSP-B offering significant potential as a novel treatment option.

Dysregulated FOXM1 signaling in the regulation of cancer stem cells

Since the introduction of the cancer stem cell (CSC) paradigm, significant advances have been made in understanding the functional and biological plasticity of these elusive components in malignancies. Endowed with self-renewing abilities and multilineage differentiation potential, CSCs have emerged as cellular drivers of virtually all facets of tumor biology, including metastasis, tumor recurrence/relapse, and drug resistance. The functional and biological characteristics of CSCs, such as self-renewal, cell fate decisions, survival, proliferation, and differentiation are regulated by an array of extracellular factors, signaling pathways, and pluripotent transcriptional factors. Besides the well-characterized regulatory role of transcription factors OCT4, SOX2, NANOG, KLF4, and MYC in CSCs, evidence for the central role of Forkhead box transcription factor FOXM1 in the establishment, maintenance, and functions of CSCs is accumulating. Conventionally identified as a master regulator of the cell cycle, a comprehensive understanding of this molecule has revealed its multifarious oncogenic potential and uncovered its role in angiogenesis, invasion, migration, self-renewal, and drug resistance. This review compiles the large body of literature that has accumulated in recent years that provides evidence for the mechanisms by which FOXM1 expression promotes stemness in glioblastoma, breast, colon, ovarian, lung, hepatic, and pancreatic carcinomas. We have also compiled the data showing the association of stem cell mediators with FOXM1 using TCGA mRNA expression data. Further, the prognostic importance of FOXM1 and other stem cell markers is presented. The delineation of FOXM1-mediated regulation of CSCs can aid in the development of molecularly targeted pharmacological approaches directed at the selective eradication of CSCs in several human malignancies.

Bioinformatics Analysis Reveals FOXM1/BUB1B Signaling Pathway as a Key Target of Neosetophomone B in Human Leukemic Cells: A Gene Network-Based Microarray Analysis

Abnormal expression of Forkhead box protein M1 (FOXM1) and serine/threonine kinase Budding uninhibited by benzimidazoles 1 (BUB1B) contributes to the development and progression of several cancers, including chronic myelogenous leukemia (CML). However, the molecular mechanism of the FOXM1/BUB1B regulatory network and the role of Neosetophomone-B (NSP-B) in leukemia remains unclear. NSP-B, a meroterpenoid fungal secondary metabolite, possesses anticancer potential in human leukemic cells lines; however, the underlying mechanism has not been elucidated. The present study aimed to explore the role of NSP-B on FOXM1/BUB1B signaling and the underlying molecular mechanism of apoptosis induction in leukemic cells. We performed gene expression profiling of NSP-B-treated and untreated leukemic cells to search for differentially expressed genes (DEGs). Interestingly BUB1B was found to be significantly downregulated (logFC -2.60, adjusted p = 0.001) in the treated cell line with the highest connectivity score among cancer genes. Analysis of TCGA data revealed overexpression of BUB1B compared to normal in most cancers and overexpression was associated with poor prognosis. BUB1B also showed a highly significant positive correlation with FOXM1 in all the TCGA cancer types. We used human leukemic cell lines (K562 and U937) as an in vitro study model to validate our findings. We found that NSP-B treatment of leukemic cells suppressed the expression of FOXM1 and BUB1B in a dose-dependent manner. In addition, NSP-B also resulted in the downregulation of FOXM1-regulated genes such as Aurora kinase A, Aurora kinase B, CDK4, and CDK6. Suppression of FOXM1 either by siRNA or NSP-B reduced BUB1B expression and enhanced cell survival inhibition and induction of apoptosis. Interestingly combination treatment of thiostrepton and NSP-B suppressed of cell viability and inducted apoptosis in leukemic cells via enhancing the activation of caspase-3 and caspase-8 compared with single-agent treatment. These results demonstrate the important role of the FOXM1/BUB1B pathway in leukemia and thus a potential therapeutic target.

The effect of protein mutations on drug binding suggests ensuing personalised drug selection

The advent of personalised medicine promises a deeper understanding of mechanisms and therefore therapies. However, the connection between genomic sequences and clinical treatments is often unclear. We studied 50 breast cancer patients belonging to a population-cohort in the state of Qatar. From Sanger sequencing, we identified several new deleterious mutations in the estrogen receptor 1 gene (ESR1). The effect of these mutations on drug treatment in the protein target encoded by ESR1, namely the estrogen receptor, was achieved via rapid and accurate protein-ligand binding affinity interaction studies which were performed for the selected drugs and the natural ligand estrogen. Four nonsynonymous mutations in the ligand-binding domain were subjected to molecular dynamics simulation using absolute and relative binding free energy methods, leading to the ranking of the efficacy of six selected drugs for patients with the mutations. Our study shows that a personalised clinical decision system can be created by integrating an individual patient's genomic data at the molecular level within a computational pipeline which ranks the efficacy of binding of particular drugs to variant proteins.

Molecular characteristics of Neisseria meningitidis in Qatar

The aim of the current study is to review the molecular characteristics of Neisseria meningitidis (N. meningitidis) in Hamad Medical Corporation, which is the provider of secondary and tertiary care in the state of Qatar. A total of 39 isolates of N. meningitidis from the period of 2013 to 2018 were revived and identified by Vitek, and susceptibility on the basis of the E test was retrieved from the patient's files. The revived isolates were subjected to multilocus sequence typing. The most common serogroup (19) of N. meningitidis was W135, of which 12 were isolated from blood and CSF. ST-11 was the most predominant ST clonal complex causing N. meningitidis cases (61.53%). Clonal complex ST-41/44 was the second most observed complex (3, 2 of which were related to serogroup B). The most frequent sequence type was 9596 (8 isolates). Determining the molecular pattern of N. meningitidis in Qatar is helpful for understanding the strains circulating in Qatar, and the study of the resistance trend of such strains may be very helpful for empirical treatment of future patients.

Epigenetic and breast cancer therapy: Promising diagnostic and therapeutic applications

The global burden of breast cancer (BC) is increasing significantly. This trend is caused by several factors such as late diagnosis, limited treatment options for certain BC subtypes, drug resistance which all lead to poor clinical outcomes. Recent research has reported the role of epigenetic alterations in the mechanism of BC pathogenesis and its hallmarks include drug resistance and stemness features. The understanding of these modifications and their significance in the management of BC carcinogenesis is challenging and requires further attention. Nevertheless, it promises to provide novel insight needed for utilizing these alterations as potential diagnostic, prognostic markers, predict treatment efficacy, as well as therapeutic agents. This highlights the importance of continuing research development to further advance the existing knowledge on epigenetics and BC carcinogenesis to overcome the current challenges. Hence, this review aims to shed light and discuss the current state of epigenetics research in the diagnosis and management of BC.

Outcome associated with EPCAM founder mutation c.499dup in Qatar

Tufting enteropathy (TE) is a rare autosomal recessive congenital enteropathy that usually requires long-term parenteral nutrition (PN). In the Arabic Peninsula, four distinct EPCAM mutations have been identified to cause TE. As consanguineous marriages are socially favored, pre-marital and pre-conception testing has become a critical disease prevention strategy. This study aimed to identify the pathogenic EPCAM mutations causing TE in Qatari families and determine possible genotype-phenotype correlations. Twenty-two TE patients from seven multiplex families with TE were identified. Blood samples were collected from patients and first-degree relatives. Exons of the gene were amplified and sequenced. Retrospective chart review and/or family interviews were conducted to determine phenotypic characteristics of the disease. Sequence analysis revealed a single, previously described c.499dup mutation in exon 5 of all families tested, suggesting a founder effect. Of the 18 patients whose full clinical information was available, three patients (17%) were off PN with a good quality of life, without intestinal transplantation, and one (6%) was receiving partial PN. Our patients with TE were severely stunted compared to a similar group of patients receiving long-term PN for short bowel syndrome, suggesting that this could possibly be due to TE rather than secondary to inadequate nutrition. Our study identified the EPCAM mutation c.499dup as the genetic defect causing TE in all the participant Qatari families. This finding should facilitate early diagnosis of TE and genetic counseling. Furthermore, it should aid in the prevention of TE through pre-marital screening, antenatal diagnosis, and pre-implantation genetic diagnosis.

Prevalence and Type Distribution of High-Risk Human Papillomavirus (HPV) in Breast Cancer: A Qatar Based Study

Human papillomavirus (HPV) has been implicated in the etiology of a variety of human cancers. Studies investigating the presence of high-risk (HR) HPV in breast tissue have generated considerable controversy over its role as a potential risk factor for breast cancer (BC). This is the first investigation reporting the prevalence and type distribution of high-risk HPV infection in breast tissue in the population of Qatar. A prospective comparison blind research study herein reconnoitered the presence of twelve HR-HPV types' DNA using multiplex PCR by screening a total of 150 fresh breast tissue specimens. Data obtained shows that HR-HPV types were found in 10% of subjects with breast cancer; of which the presence of HPV was confirmed in 4/33 (12.12%) of invasive carcinomas. These findings, the first reported from the population of Qatar, suggest that the selective presence of HPV in breast tissue is likely to be a related factor in the progression of certain cases of breast cancer.

Molecular Diagnosis of Rare Autosomal Recessive Escobar Syndrome in a Consanguineous Pakistani Family

Background: Escobar syndrome, a nonlethal variant of multiple pterygium syndromes (MPS), is a rare autosomal recessive disorder characterized by pterygia and multiple joint contractures along with other anomalies. Variants in cholinergic receptor nicotinic gamma subunit (CHRNG) have been previously reported in patients with Escobar syndrome. Objective: We studied a consanguineous Pakistani family affected with Escobar syndrome to identify the underlying genetic defect through short tandem repeat (STR) genotyping and direct DNA sequencing. Results: Genotyping with microsatellite markers (D2S427, D2S2344, and D2S206) revealed linkage of the disease phenotype in the family to the CHRNG locus. Using Sanger sequencing, we identified a homozygous nonsense CHRNG variant c.136C>T (p.R46*), predicted to produce a truncated protein that leads to acetylcholine receptor deficiency, causing MPS. The unaffected parents and siblings in the family were heterozygous carriers of this disease-causing variant. Conclusion: We report the identification of a nonsense CHRNG variant in a consanguineous Pakistani family affected with Escobar syndrome.

Reproductive oocyte/embryo genetic analysis: comparison between fluorescence in-situ hybridization and comparative genomic hybridization

Multiple displacement amplification (MDA) renders an increased quantity of genomic DNA available for comparative genomic hybridization (CGH), enabling it to be used to identify genomic imbalances in human blastomeres. The karyotypic lineage of 57 blastocysts derived from 11 ovum donors following ovarian stimulation was examined. CGH was performed on all first polar bodies, and linearly on corresponding second polar bodies and blastomeres. A diploid karyotype was propagated from the prefertilized oocyte to the embryo in 25 (44%) sets of analyses. In 32/57 sets (56%), aneuploidy was detected in the post-fertilized zygotes/embryos and in nine (28%) of such cases the aneuploidy was 'chaotic' (> or =3 chromosomes). In 4/57 cases (7%) mitotic aneuploidy was observed. CGH and fluorescence in-situ hybridization (FISH) were concurrently performed on two blastomeres removed from each of 44 embryos obtained from four patients. In 43 (98%) of these embryos there was a direct karyotypic correlation between nine-probe commercial FISH and CGH. CGH identified > or =15% more chromosomal abnormalities than through FISH alone. The linear propagation using MDA-CGH, of the same karyotypic abnormalities that affected the oocyte of origin, in the corresponding embryos, coupled with the fact that CGH confirmed the aneuploidies identified through FISH, validates the accuracy and reliability of CGH technology.

sHLA-G expression: is it really worth measuring?

HLA-G is believed to play a pivotal role in the immunoprotection of the semiallogenic embryo. Its expression during pre- and early implantation is correlated with the cleavage rate of the embryo. Studies in congenic mice have revealed that mRNA of both the maternal and paternal haplotypes are present in zygotes and in embryos at all stages of development.

Influence of early ICSI-derived embryo sHLA-G expression on pregnancy and implantation rates: a prospective study

BACKGROUND

We have previously reported the retrospective observation that when at least one embryo, transferred on day 3, expressed sHLA-G above the geometric mean (sHLA-G+) 46 h post-ICSI, there was a marked improvement in both pregnancy (PR) and implantation (IR) rates.

METHODS

The media surrounding individual embryos derived from ICSI performed on oocytes from 482 women < or =43 years of age were tested for sHLA-G expression by specific ELISA.

RESULTS

We report here prospective results showing improved IVF results following the transfer of 'good quality' embryos (7-9 cells with <20% fragmentation) by preferentially including at least one sHLA-G+ embryos. PR and IR for women < or =38 years were 63% and 32% when one transferred embryo was sHLA-G+, and 69% and 36% when at least two embryos were sHLA-G+. When none of the embryos transferred was sHLA-G+, PR and IR were 25% and 13%, respectively. Comparable PR and IR for women 39-43 years were 29% and 11% when none of the transferred embryos were sHLA-G+; 38% and 15% when at least one sHLA-G+ embryo was transferred; and 61% and 26% when at least two 2 sHLA-G+ embryos were transferred. The data were stratified by patient age.

CONCLUSIONS

PR and IR increased with the addition of each sHLA-G+ embryo, regardless of age. While there are significant barriers to routine embryo sHLA-G testing, we believe that if implemented, this would provide a mechanism for optimizing IVF PR while minimizing the risk of multiple pregnancies.

The Graduated Embryo Score (GES) predicts blastocyst formation and pregnancy rate from cleavage-stage embryos

BACKGROUND

Embryo morphology and cleavage rates alone do not consistently identify embryos with high implantation potential following IVF. Blastocyst transfer has been reported to improve success rates by identifying potentially superior quality embryos. Algorithms for predicting IVF outcomes based on the presence of early developmental milestones have been proposed. Here we introduce the Graduated Embryo Score (GES).

METHODS

Nucleolar alignment along the pronuclear axis, regular cleavage and degree of fragmentation at the first cell division, and cell number and morphology on day 3 were weighted to create a possible GES of 100 for each of 1245 fertilized embryos derived from 109 patients aged <40 years. The GES was correlated with IVF outcome.

RESULTS

Of 983 embryos for extended culture, 349 (36%) developed to blastocyst and 180 (18%) were good quality (grade I-II). When ranked by cell number and morphology alone, 34% of embryos with > or =7 cells and <20% fragmentation formed good quality blastocysts. Using GES, embryos scoring 90-100 had 64% blastocyst formation compared with 31% scoring 70-85 and with 11% scoring 30-65. Embryos scoring 70-100 had 44% blastocyst development compared with 9% scoring 0-65. Fifty-six patients (51%) conceived on-going gestations from 294 transferred embryos. In patients with at least one transferred embryo scoring > or =70, the pregnancy rate was 59% compared with 34% if all embryos scored <70. The overall implantation rate was 28%. Among embryos scoring 70-100, an implantation rate of 39% was seen, compared with 24% among embryos scoring 0-65.

CONCLUSIONS

Predicting which cleaved embryos will form blastocysts could permit the high success rates associated with blastocyst transfer to be achieved from day 3 embryo transfer.

Prevalence of GBV-C/hepatitis G virus viremia and anti-E2 in Canadian blood donors

BACKGROUND AND OBJECTIVES

GB virus C (GBV-C)/hepatitis G virus (HGV) is a recently recognized parenterally and sexually transmitted agent. The prevalence of GBV-C/HGV markers in Canadian blood donors has not been previously studied and was therefore determined.

MATERIALS AND METHODS

Blood donors [identity unlinked (IU), short-term temporarily deferred (STTD) and autologous groups] and donor samples with antibodies to hepatitis C (anti-HCV) or hepatitis B core were tested for GBV-C/HGV RNA and for antibodies to E2 antigen (anti-E2).

RESULTS

GBV-C/HGV RNA was found in 1.1% and anti-E2 in 7.3% of the combined IU/STTD donor group. Viremia was much more common in anti-HCV-positive samples (12.5%); anti-E2 was present in >50% of this group. In the STTD group, female gender was significantly associated with viremia.

CONCLUSION

GBV-C/HGV infection is relatively common in Canadian donors, and a small proportion are viremic. The association of female gender and viremia was unexpected. Further study is needed to clarify the epidemiology and natural history of GBV-C/HGV infection.

Prevalence of GBV-C/hepatitis G virus viremia and anti-E2 in Canadian blood donors

BACKGROUND AND OBJECTIVES

GB virus C (GBV-C)/hepatitis G virus (HGV) is a recently recognized parenterally and sexually transmitted agent. The prevalence of GBV-C/HGV markers in Canadian blood donors has not been previously studied and was therefore determined.

MATERIALS AND METHODS

Blood donors [identity unlinked (IU), short-term temporarily deferred (STTD) and autologous groups] and donor samples with antibodies to hepatitis C (anti-HCV) or hepatitis B core were tested for GBV-C/HGV RNA and for antibodies to E2 antigen (anti-E2).

RESULTS

GBV-C/HGV RNA was found in 1.1% and anti-E2 in 7.3% of the combined IU/STTD donor group. Viremia was much more common in anti-HCV-positive samples (12.5%); anti-E2 was present in >50% of this group. In the STTD group, female gender was significantly associated with viremia.

CONCLUSION

GBV-C/HGV infection is relatively common in Canadian donors, and a small proportion are viremic. The association of female gender and viremia was unexpected. Further study is needed to clarify the epidemiology and natural history of GBV-C/HGV infection.

Transfusion-transmitted malaria in Canada

Three cases of transfusion-transmitted malaria in Canada are described. Although very rare, this diagnosis should be considered in transfusion recipients who have undiagnosed symptoms consistent with malaria. Thick and thin blood smears should be urgently examined to exclude this possibility.

Antibodies to phosphatidylethanolamine and phosphatidylserine are associated with increased natural killer cell activity in non-male factor infertility patients

Antiphospholipid antibodies (APA) have been identified in patients with recurrent pregnancy loss and IVF failure. Of these, antiphosphatidylethanolamine (aPE) and antiphosphatidylserine (aPS) may have special significance. A link between increased natural killer cell activity (NKa+) and trophoblast cell apoptosis has also been reported. This study was undertaken to determine how the APA profile was associated with peripheral NK cell activity. We evaluated 197 female IVF candidates for APA and NKa. Eighty-nine patients (45%) were APA+ and of these, 51 (57%) were aPE/aPS+. Fifty-four patients (27%) had increased NK cell activity. Some 51% of APA+ and 78% of aPE/aPS+ patients had increased NK cell activity compared with 8% and 13% when APA and aPE/aPS tested negative respectively (P: < 0.0001). Non-male factor infertility patients were APA+ and NKa+ in 57% and 34% of cases respectively, compared with 19% and 13% if a pure male factor was present. Some 88% of aPE/aPS+, non-male factor patients had increased NK cell activity, compared with 12% who tested aPE/aPS negative (P: < 0.0001) and 25% of aPE/aPS+, isolated male factor patients (P: < 0.0001). These findings establish a direct relationship between APA (specifically aPE/aPS) and increased peripheral NK cell activity among non-male factor infertility patients. It is possible that APA do not directly cause reproductive failure but rather function as markers or intermediaries for an underlying, abnormal activation of cellular immunity.

Effect of premedication guidelines and leukoreduction on the rate of febrile nonhaemolytic platelet transfusion reactions

Platelet transfusion reactions were prospectively studied in haematology/oncology patients at five university teaching hospitals over three consecutive summers. The initial summer study provided baseline information on the use of premedications and the rate of platelet transfusion reactions (fever, chills, rigors and hives). Most (73%) platelet recipients were premedicated and 30% (95% CI 28-33%) of transfusions were complicated by reactions. The second study followed implementation of guidelines for premedicating platelet transfusions. Despite a marked reduction in premedication (50%), there was little change in the platelet transfusion reaction rate, 26% (95% CI 24-29%), or the type of reactions. The third study followed implementation of prestorage platelet leukoreduction while maintaining the premedication guidelines. The reaction rate decreased to 19% (95% CI 17-22%). For nonleukoreduced platelets, there was a statistically significant association between the platelet age and reaction rate (P = 0.04). For leukoreduced platelets, there was no statistically significant association between platelet age and reaction rate (P = 0.5). Plasma reduction of nonleukoreduced platelet products also reduced the reaction rate. These prospective studies document a high rate of platelet transfusion reactions in haematology/oncology patients and indicate premedication use can be reduced without increasing the reaction rate. Prestorage leukoreduction and/or plasma reduction of platelet products reduces but does not eliminate febrile nonhemolytic platelet transfusion reactions.