Genotype, oxidase status, and preceding infection or autoinflammation do not affect allogeneic HCT outcomes for CGD

Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by life-threatening infections and inflammatory conditions. Hematopoietic cell transplantation (HCT) is the definitive treatment for CGD, but questions remain regarding patient selection and impact of active disease on transplant outcomes. We performed a multi-institutional retrospective and prospective study of 391 patients with CGD treated either conventionally (non-HCT) enrolled from 2004 to 2018 or with HCT from 1996 to 2018. Median follow-up after HCT was 3.7 years with a 3-year overall survival of 82% and event-free survival of 69%. In a multivariate analysis, a Lansky/Karnofsky score <90 and use of HLA-mismatched donors negatively affected survival. Age, genotype, and oxidase status did not affect outcomes. Before HCT, patients had higher infection density, higher frequency of noninfectious lung and liver diseases, and more steroid use than conventionally treated patients; however, these issues did not adversely affect HCT survival. Presence of pre-HCT inflammatory conditions was associated with chronic graft-versus-host disease. Graft failure or receipt of a second HCT occurred in 17.6% of the patients and was associated with melphalan-based conditioning and/or early mixed chimerism. At 3 to 5 years after HCT, patients had improved growth and nutrition, resolved infections and inflammatory disease, and lower rates of antimicrobial prophylaxis or corticosteroid use compared with both their baseline and those of conventionally treated patients. HCT leads to durable resolution of CGD symptoms and lowers the burden of the disease. Patients with active infection or inflammation are candidates for transplants; HCT should be considered before the development of comorbidities that could affect performance status. This trial was registered at www.clinicaltrials.gov as #NCT02082353.

A diagnostic classifier for pediatric chronic graft-versus-host disease: results of the ABLE/PBMTC 1202 study

The National Institutes of Health Consensus criteria for chronic graft-versus-host disease (cGVHD) diagnosis can be challenging to apply in children, making pediatric cGVHD diagnosis difficult. We aimed to identify diagnostic pediatric cGVHD biomarkers that would complement the current clinical criteria and help differentiate cGVHD from non-cGVHD. The Applied Biomarkers of Late Effects of Childhood Cancer (ABLE) study, open at 27 transplant centers, prospectively evaluated 302 pediatric patients after hematopoietic cell transplant (234 evaluable). Forty-four patients developed cGVHD. Mixed and fixed effect regression analyses were performed on diagnostic cGVHD onset blood samples for cellular and plasma biomarkers, with individual markers declared relevant if they met 3 criteria: an effect ratio ≥1.3 or ≤0.75; an area under the curve (AUC) of ≥0.60; and a P value <5.814 × 10-4 (Bonferroni correction) (mixed effect) or <.05 (fixed effect). To address the complexity of cGVHD diagnosis in children, we built a machine learning-based classifier that combined multiple cellular and plasma biomarkers with clinical factors. Decreases in regulatory natural killer cells, naïve CD4 T helper cells, and naïve regulatory T cells, and elevated levels of CXCL9, CXCL10, CXCL11, ST2, ICAM-1, and soluble CD13 (sCD13) characterize the onset of cGVHD. Evaluation of the time dependence revealed that sCD13, ST2, and ICAM-1 levels varied with the timing of cGVHD onset. The cGVHD diagnostic classifier achieved an AUC of 0.89, with a positive predictive value of 82% and a negative predictive value of 80% for diagnosing cGVHD. Our polyomic approach to building a diagnostic classifier could help improve the diagnosis of cGVHD in children but requires validation in future prospective studies. This trial was registered at www.clinicaltrials.gov as #NCT02067832.

Case Report: Unmanipulated Matched Sibling Donor Hematopoietic Cell Transplantation In TBX1 Congenital Athymia: A Lifesaving Therapeutic Approach When Facing a Systemic Viral Infection

Congenital athymia can present with severe T cell lymphopenia (TCL) in the newborn period, which can be detected by decreased T cell receptor excision circles (TRECs) on newborn screening (NBS). The most common thymic stromal defect causing selective TCL is 22q11.2 deletion syndrome (22q11.2DS). T-box transcription factor 1 (TBX1), present on chromosome 22, is responsible for thymic epithelial development. Single variants in TBX1 causing haploinsufficiency cause a clinical syndrome that mimics 22q11.2DS. Definitive therapy for congenital athymia is allogeneic thymic transplantation. However, universal availability of such therapy is limited. We present a patient with early diagnosis of congenital athymia due to TBX1 haploinsufficiency. While evaluating for thymic transplantation, she developed Omenn Syndrome (OS) and life-threatening adenoviremia. Despite treatment with anti-virals and cytotoxic T lymphocytes (CTLs), life threatening adenoviremia persisted. Given the imminent need for rapid establishment of T cell immunity and viral clearance, the patient underwent an unmanipulated matched sibling donor (MSD) hematopoietic cell transplant (HCT), ultimately achieving post-thymic donor-derived engraftment, viral clearance, and immune reconstitution. This case illustrates that because of the slower immune recovery that occurs following thymus transplantation and the restricted availability of thymus transplantation globally, clinicians may consider CTL therapy and HCT to treat congenital athymia patients with severe infections.

Correction: Chronic Granulomatous Disease-Associated IBD Resolves and Does Not Adversely Impact Survival Following Allogeneic HCT

The original version of this article unfortunately contained the missing author, Caridad Martinez. The authors would like to correct the list. We apologize for any inconvenience that this may have caused. The correct author list is shown above.

Immune profile differences between chronic GVHD and late acute GVHD: results of the ABLE/PBMTC 1202 studies

Human graft-versus-host disease (GVHD) biology beyond 3 months after hematopoietic stem cell transplantation (HSCT) is complex. The Applied Biomarker in Late Effects of Childhood Cancer study (ABLE/PBMTC1202, NCT02067832) evaluated the immune profiles in chronic GVHD (cGVHD) and late acute GVHD (L-aGVHD). Peripheral blood immune cell and plasma markers were analyzed at day 100 post-HSCT and correlated with GVHD diagnosed according to the National Institutes of Health consensus criteria (NIH-CC) for cGVHD. Of 302 children enrolled, 241 were evaluable as L-aGVHD, cGVHD, active L-aGVHD or cGVHD, and no cGVHD/L-aGVHD. Significant marker differences, adjusted for major clinical factors, were defined as meeting all 3 criteria: receiver-operating characteristic area under the curve ≥0.60, P ≤ .05, and effect ratio ≥1.3 or ≤0.75. Patients with only distinctive features but determined as cGVHD by the adjudication committee (non-NIH-CC) had immune profiles similar to NIH-CC. Both cGVHD and L-aGVHD had decreased transitional B cells and increased cytolytic natural killer (NK) cells. cGVHD had additional abnormalities, with increased activated T cells, naive helper T (Th) and cytotoxic T cells, loss of CD56bright regulatory NK cells, and increased ST2 and soluble CD13. Active L-aGVHD before day 114 had additional abnormalities in naive Th, naive regulatory T (Treg) cell populations, and cytokines, and active cGVHD had an increase in PD-1- and a decrease in PD-1+ memory Treg cells. Unsupervised analysis appeared to show a progression of immune abnormalities from no cGVHD/L-aGVHD to L-aGVHD, with the most complex pattern in cGVHD. Comprehensive immune profiling will allow us to better understand how to minimize L-aGVHD and cGVHD. Further confirmation in adult and pediatric cohorts is needed.

Hematopoietic Cell Transplantation in Patients With Primary Immune Regulatory Disorders (PIRD): A Primary Immune Deficiency Treatment Consortium (PIDTC) Survey

Primary Immune Regulatory Disorders (PIRD) are an expanding group of diseases caused by gene defects in several different immune pathways, such as regulatory T cell function. Patients with PIRD develop clinical manifestations associated with diminished and exaggerated immune responses. Management of these patients is complicated; oftentimes immunosuppressive therapies are insufficient, and patients may require hematopoietic cell transplant (HCT) for treatment. Analysis of HCT data in PIRD patients have previously focused on a single gene defect. This study surveyed transplanted patients with a phenotypic clinical picture consistent with PIRD treated in 33 Primary Immune Deficiency Treatment Consortium centers and European centers. Our data showed that PIRD patients often had immunodeficient and autoimmune features affecting multiple organ systems. Transplantation resulted in resolution of disease manifestations in more than half of the patients with an overall 5-years survival of 67%. This study, the first to encompass disorders across the PIRD spectrum, highlights the need for further research in PIRD management.

Benefits and challenges with diagnosing chronic and late acute GVHD in children using the NIH consensus criteria

Chronic graft-versus-host disease (cGVHD) and late acute graft-versus-host disease (L-aGVHD) are understudied complications of allogeneic hematopoietic stem cell transplantation in children. The National Institutes of Health Consensus Criteria (NIH-CC) were designed to improve the diagnostic accuracy of cGVHD and to better classify graft-versus-host disease (GVHD) syndromes but have not been validated in patients <18 years of age. The objectives of this prospective multi-institution study were to determine: (1) whether the NIH-CC could be used to diagnose pediatric cGVHD and whether the criteria operationalize well in a multi-institution study; (2) the frequency of cGVHD and L-aGVHD in children using the NIH-CC; and (3) the clinical features and risk factors for cGVHD and L-aGVHD using the NIH-CC. Twenty-seven transplant centers enrolled 302 patients <18 years of age before conditioning and prospectively followed them for 1 year posttransplant for development of cGVHD. Centers justified their cGVHD diagnosis according to the NIH-CC using central review and a study adjudication committee. A total of 28.2% of reported cGVHD cases was reclassified, usually as L-aGVHD, following study committee review. Similar incidence of cGVHD and L-aGVHD was found (21% and 24.7%, respectively). The most common organs involved with diagnostic or distinctive manifestations of cGVHD in children include the mouth, skin, eyes, and lungs. Importantly, the 2014 NIH-CC for bronchiolitis obliterans syndrome perform poorly in children. Past acute GVHD and peripheral blood grafts are major risk factors for cGVHD and L-aGVHD, with recipients ≥12 years of age being at risk for cGVHD. Applying the NIH-CC in pediatrics is feasible and reliable; however, further refinement of the criteria specifically for children is needed.

Low-dose azacitidine for relapse prevention after allogeneic hematopoietic cell transplantation in children with myeloid malignancies

BACKGROUND

The prognosis of children who relapse after allogeneic hematopoietic cell transplant (alloHCT) for myeloid malignancies remains poor.

PROCEDURE

To describe the safety and feasibility of post-transplant azacitidine for relapse prevention, we retrospectively reviewed the charts of 18 children undergoing alloHCT for myeloid malignancies.

RESULTS

There were 15 evaluable patients since three patients did not receive planned azacitidine due to early relapse or TRM. Azacitidine (32 mg/m² /dose for 5 days, in 28-day cycles as tolerated up to 1 year post-transplant) was started at a median of 66 days post-transplant (range 42-118). Two-thirds (10/15) of patients received eight or more cycles. Five patients stopped therapy early, only one attributable to toxicity. Mild myelosuppression was the most common reason for cycle delays. Dose modifications were made in three patients. There were three relapses, two of which occurred in patients in CR2 and one in CR1, with a median follow-up of 20 months (range 12.5-28), and no TRM in patients who received azacitidine.

CONCLUSIONS

Post-transplant azacitidine in children is safe and feasible, with most patients successfully receiving all planned cycles. Despite the limitations of a small cohort, low relapse incidence suggests a potential benefit in disease control that warrants further investigation.

Mixed chimerism and graft loss in pediatric recipients of an alemtuzumab-based reduced-intensity conditioning regimen for non-malignant disease

BACKGROUND

Reduced-intensity conditioning (RIC) regimens can mitigate the toxicity of hematopoietic cell transplantation (HCT) in children with non-malignant diseases, but are associated with increased risk for post-transplant mixed donor/recipient chimerism (MC) and/or graft loss (GL). Intervention with donor lymphocytes or stem cell boosts (DLI/boost) may be necessary, but there is limited information about timing and results of intervention.

PROCEDURE

We retrospectively evaluated 31 consecutive pediatric recipients of an alemtuzumab-based RIC HCT at the Children's Hospital of Philadelphia from May 2007 to December 2012 to determine the incidence of MC, GL, and use of DLI/boost. All patients received alemtuzumab with either fludarabine (150 mg/m(2) )/melphalan (140 mg/m(2) ) (n = 30) or fludarabine/busulfan (n = 1), and unmanipulated marrow grafts from related (48%) or matched unrelated (52%) donors.

RESULTS

Of surviving patients, 67% and 44% displayed MC and MC with ≤80% donor contribution (MC ≤ 80%), respectively. Rates of MC, MC ≤ 80%, DLI/boost, and GL were significantly higher in recipients of proximal/intermediate (100%, 73%, 46%, and 46%, respectively) compared to distal alemtuzumab (44%, 25%, 6%, and 6%, respectively). Event-free and overall survival was significantly lower in HLH compared with non-HLH patients. Twenty percent of patients required DLI/boost, and DLI/boost did not affect the incidence of GL.

CONCLUSIONS

RIC with proximal/intermediate alemtuzumab is associated with high rates of MC, need for DLI/boost, and GL.

Acquired isochromosome 12p, somatic TP53 and PTEN mutations, and a germline ATM variant in an adolescent male with concurrent acute megakaryoblastic leukemia and mediastinal germ cell tumor

Previous reports have described an association between hematologic malignancies (HMs) and extragonadal germ cell tumor (GCT). Most patients have been adolescent males with mediastinal nonseminomatous GCT. Although a variety of HMs have been reported, there is a striking predilection toward acute megakaryoblastic leukemia (AMKL). Shared cytogenetic anomalies--particularly isochromosome 12p [i(12p)]--have suggested common clonal origins to the tumors. We report the case of a 17-year-old boy presenting with AMKL and a synchronous mediastinal GCT, with the characteristic i(12p) in both neoplasms. The common clonal origin of the AMKL and GCT was further confirmed with massively parallel sequencing, which identified somatic TP53 and PTEN mutations, as well as a rare germline ATM variant. Although these represent commonly mutated genes in cancer, this combination of mutations is not typically associated with either GCT or AMKL, suggesting that these tumors may represent unique biologic entities when they co-occur.

Immunologic recovery in children after alternative donor allogeneic transplantation for hematologic malignancies: comparison of recipients of partially T cell-depleted peripheral blood stem cells and umbilical cord blood

Impaired immunologic recovery (IR) after hematopoietic stem cell transplantation (HSCT) is associated with increased risk for infections and relapse. Stem cell source and graft manipulation influence the kinetics of IR. Partial T cell depletion of peripheral blood stem cell (PBSC) grafts is a novel alternative method of graft manipulation for children. We compared IR in children undergoing HSCT for hematologic malignancies receiving either T cell-depleted (TCD)-PBSCs (n = 55) or umbilical cord blood (UCB) (n = 21) over a 7-year period at a single institution. PBSC grafts underwent ex vivo negative selection for CD3(+) cells using the CliniMACS system with partial T cell add-back. Recovery of CD4(+) T cells was significantly delayed in TCD-PBSC recipients compared with UCB recipients, owing to impaired CD4(+)/CD45RA(+) (naïve) T cell lymphopoiesis. Recovery of total CD3(+) cells and CD3(+)/CD8(+) cells was similar in the 2 groups. The TCD-PBSC recipients had a marked deficit in CD19(+) and, to a lesser extent, IgA/IgM, owing to the need for B cell depletion of these grafts to attenuate the risk of lymphoproliferative disease after TCD HSCT. There were no significant between-group differences in response to mitogen stimulation, time to independence from intravenous immunoglobulin supplementation, or incidence of viral reactivation. Transplantation outcomes of relapse, transplantation-related mortality, event-free survival, and overall survival were similar in the 2 groups. Efforts to enhance IR after partial TCD-PBSC transplantation, such as selective αβ T cell depletion, hold promise for further improvement of this transplantation approach.

Does heart failure etiology, New York Heart Association class, or ejection fraction affect the ability of clopidogrel to inhibit heightened platelet activity?

The ability of clopidogrel to inhibit platelet function in patients with congestive heart failure (CHF) was proved by the PLUTO-CHF trial. We retrospectively analyzed platelet characteristics with respect to CHF etiology, class, and ejection fraction in patients enrolled in the PLUTO-CHF study. Twenty-five patients were divided by CHF etiology, severity, and ejection fraction. All patients received aspirin 325 mg for at least 1 month prior to screening. Platelet function studies were performed at baseline and after 30 days of therapy. There were no differences in platelet parameters dependent on clinical characteristics of CHF, except for a significant (P = 0.023) decrease in platelet/endothelial cell adhesion molecule 1 (PECAM-1) expression in the New York Heart Association class III-IV due to the higher baseline values. Therapy with clopidogrel resulted in a significant inhibition of platelet activity assessed by ADP-induced and epinephrine-induced aggregation, closure time, expression of PECAM-1, glycoprotein Ib, glycoprotein IIb/IIIa antigen, glycoprotein IIb/IIIa activity with PAC-1, CD151, and reduced formation of platelet-leukocyte conjugates when compared with baseline. Clopidogrel provides antiplatelet protection in the broad spectrum of patients with CHF independently of its etiology, severity, or myocardial contractility. This uniform platelet inhibition with clopidogrel may be an important consideration in designing future large-scale clinical trials.

Lack of uniform platelet activation in patients after ischemic stroke and choice of antiplatelet therapy

INTRODUCTION

Platelets play an important role in the natural history of ischemic stroke, and are known to be activated in the acute phase. Although aspirin reduces risks of myocardial infarction, stroke and cardiovascular death, the extent of platelet action and the effect of aspirin on platelet function in patients recovering from stroke remain unclear.

METHODS

We studied 120 individuals divided into three equal groups: aspirin-free patients after ischemic stroke, post-stroke patients receiving aspirin (81-650 mg/daily), and aspirin-free subjects with multiple risk factors for vascular disease. Conventional platelet aggregation induced by 5 microM ADP and 5 microM epinephrine, cartridge-based analyzers (Ultegra, and PFA-100) readings, and expression of CD31, CD41a, CD42b, GPIIb/IIIa activity, CD51/CD61, CD62p, CD63, CD107a, CD154, CD165, formation of platelet-monocyte aggregates, intact (SPAN12), and cleaved (WEDE15) PAR-1 thrombin receptors by flow cytometry were analyzed.

RESULTS

There were no differences between aspirin-free post-stroke patients and aspirin-free controls. Although aggregation was slightly higher, 12 out of the 14 receptor analyses, were surprisingly lower in the post-stroke cohort. Aspirin-treated patients exhibited highly significant inhibition of epinephrine-induced aggregation (p=0.0001), prolongation of the closure time (p=0.03), and reduction of the aspirin reactive units (p=0.02) measured by the Ultegra device. In addition, surface platelet expression of thrombospondin (p=0.001), GPIIb/IIIa activity (p=0.04), P-selectin (p=0.03), CD40-ligand (p=0.04), CD165 (p=0.02), the formation of the platelet-monocyte aggregates (p=0.01), and intact epitope of PAR-1 thrombin receptor (p=0.03) were significantly lower in the aspirin-treated group.

CONCLUSIONS

Platelets are not activated in aspirin-free patients after ischemic stroke. Platelet function is significantly inhibited in those treated with aspirin when compared with healthy subjects with risk factors for vascular disease. Bleeding complications and hemorrhagic transformations after aggressive antiplatelet regimens could be related to the decreased or normal baseline platelet characteristics in such patients. Further analysis of platelet heterogeneity and its clinical significance remains to be determined in randomized trials.

Absence of Interaction Between Atorvastatin or Other Statins and Clopidogrel

BACKGROUND

Some, but not all, post hoc analyses have suggested that the antiplatelet effects of clopidogrel are inhibited by atorvastatin. We sought to address this issue prospectively by performing serial measurements of 19 platelet characteristics using conventional aggregometry, rapid analyzers, and flow cytometry.

METHODS

The Interaction of Atorvastatin and Clopidogrel Study (Interaction Study) was designed for patients undergoing coronary stenting. All patients (n = 75) received 325 mg of aspirin daily for at least 1 week and 300 mg of clopidogrel immediately prior to stent implantation. They had been taking atorvastatin (n = 25), any other statin (n = 25), or no statin (n = 25) for at least 30 days prior to stenting. The main outcome measure was comparison of platelet biomarkers 4 and 24 hours after clopidogrel administration between study groups.

RESULTS

At baseline, patients from both statin groups exhibited diminished platelet aggregation and reduced platelet expression of G-protein-coupled protease-activated thrombin receptor (PAR)-1. There were no significant differences in measured platelet characteristics among the study groups 4 and 24 hours after clopidogrel intake, with the exception of a lower collagen-induced aggregation at 24 hours and a constantly diminished expression of PAR-1 in patients treated with any statin.

CONCLUSIONS

Statins in general, and atorvastatin in particular, do not affect the ability of clopidogrel to inhibit platelet function in patients undergoing coronary stenting. These prospective data also suggest that statins may inhibit platelets directly via yet unknown mechanism(s) possibly related to the regulation of the PAR-1 thrombin receptors.

Selective serotonin reuptake inhibitors yield additional antiplatelet protection in patients with congestive heart failure treated with antecedent aspirin

Clinical depression has been identified as an independent risk factor for increased mortality in patients with coronary artery disease. Enhanced platelet activity has been suggested as the mechanism responsible for this adverse association. Selective serotonin reuptake inhibitors (SSRIs) are known to inhibit platelets in patients undergoing coronary stenting. We sought to determine whether concomitant therapy with SSRIs would yield additional anti-platelet benefit in patients with congestive heart failure (CHF) already treated with antecedent aspirin. A total of 88 patients with left ventricular ejection fraction (LVEF) <40% or CHF symptoms in the setting of preserved systolic function and NYHA Class II-IV were analyzed. Of these, 23 patients (26%) were chronic SSRI users (SSRI+), and 65 patients were free from SSRI therapy (SSRI-). All patients received aspirin (325 mg) for at least 1 month prior to platelet studies. Platelets were assessed by aggregometry, flow cytometry and a rapid analyzer. The SSRI+ group exhibited a substantial decrease in platelet activity when compared with SSRI- patients, as manifested by a significant reduction in ADP- (P=0.001), and collagen-induced (P=0.02) aggregation, and the expression of PECAM-1 (P=0.03), GPIb (P=0.03), GP IIb/IIIa antigen (P=0.02) and GP IIb/IIIa activity with PAC-1 antibody (P=0.04) and P-selectin (P=0.02). Therapy with SSRIs also resulted in the reduced formation of platelet-leukocyte microparticles (P=0.01). Epinephrine-induced aggregation in plasma, collagen-induced whole blood aggregation, closure time and expression of vitronectin receptor, CD63, CD107a, CD107b and CD151 did not differ between groups. In patients with CHF already on aspirin, SSRI therapy was associated with further inhibition of platelet function. This observation may help to explain some of the clinical benefits associated with SSRI therapy. Further clinical trials may help to elucidate the potential outcome benefits of SSRIs in other potential thrombotic circumstances.

Aspirin inhibits surface glycoprotein IIb/IIIa, P-selectin, CD63, and CD107a receptor expression on human platelets

Platelet inhibition after aspirin therapy reduces the risk for the development of acute coronary syndromes. However, the mechanism by which aspirin affect platelets other than by prostaglandin blockade is unclear. We sought to determine the in vitro effects of aspirin on the surface expression of nine platelet receptors using whole blood flow cytometry. Blood from 24 healthy volunteers was incubated for 30 min with 1.8 and 7.2 mg/l phosphate-buffered saline-diluted acetylsalicylic acid in the presence or absence of apyrase. Platelet serotonin release, and the surface expression of platelet receptors with or without apyrase were determined using the following monoclonal antibodies: anit-CD41 [glycoprotein (GP)IIb/IIIa], CD42b (GPIb), CD62p (P-selectin), CD51/CD61 (vitronectin receptor), CD31 [platelet/endothelial cellular adhesion molecule-1 (PECAM-1)], CD107a [lysosomal associated membrane protein (LAMP)-1], CD107b (LAMP-2), CD63 (LIMP or LAMP-3), and CD151 (PETA-3). Samples were then immediately fixed with 2% paraformaldehyde, and run on the flow cytometer within 48 h. Aspirin does not affect serotonin release from human platelets. Dose-dependent inhibition of GPIIb/IIIa, P-selectin, CD63, and CD107a receptor expression was observed in the aspirin-treated whole-blood samples. Apyrase potentiates the effects of aspirin, and independently inhibits PECAM-1. In addition to the known effect of irreversibly inhibiting platelet cyclooxygenase-1, thereby blocking thromboxane A(2) synthesis, it appears that aspirin exhibits direct effects on selective major platelet receptors.

Effects of in vitro exposure of alcohol on surface receptor expression of human platelets

Platelet inhibition after moderate alcohol consumption in patients with ischaemic heart disease may contribute to reducing the risk for developing acute coronary syndromes. However, the mechanism by which ethanol affects platelets is not clarified. We sought to determine the in vitro effects of alcohol on the surface expression of human platelet receptors using whole blood flow cytometry. Blood samples from 10 healthy volunteers were incubated for 30 min with 25 and 50 mmol l(-1) of phosphate buffered saline diluted grain ethanol, concentrations often used in in vitro studies. The surface expression of platelet receptors was determined by flow cytometry after fixation with 2% paraformaldehyde using the following monoclonal antibodies: CD 41 (GP IIb/IIIa), CD 42b (GP Ib), CD 62p (P-selectin), CD 51/CD 61 (vitronectin receptor), CD 31 (PECAM-1), CD 107a (LAMP-1), CD 107b (LAMP-2), CD 63 (LIMP, LAMP-3) and CD 151 (PETA-3). Dose-dependent inhibition of GP IIb/IIIa, P-selectin, CD 63 and CD 107a receptor expression was observed in the ethanol-treated whole blood samples. This study for the first time establishes a direct effect of ethanol on selective major platelet receptors. Beneficial cardiovascular properties of moderate alcohol consumption may be explained by ethanol's antiplatelet action.