Teresa Paglieroni

HLA class II antibodies in transfusion‐related acute lung injury

BACKGROUND: Transfusion‐related acute lung injury (TRALI) is a serious, sometimes fatal, complication of transfusion. Granulocyte and HLA class I antibodies present in blood donors have been associated with TRALI. HLA class II antibodies have recently been described in a few cases of TRALI.

TRALI: correlation of antigen-antibody and monocyte activation in donor-recipient pairs.

BACKGROUND : TRALI may be a severe reaction associated with transfusion of plasma‐containing blood components. TRALI has usually been associated with antibodies against granulocytes and HLA class I antigens, but more recently with antibodies against HLA class II and monocytes. TRALI cases were investigated to determine correlation between antigen and antibody. Additionally, activation of monocytes by TRALI serums was studied.

The effects of flavanol-rich cocoa and aspirin on ex vivo platelet function

BACKGROUND Flavanols modulate platelet function in vitro, but less is known of their in vivo effects and how they compare to pharmacological platelet inhibitors. We investigated the effect of a flavanol-rich cocoa beverage (897 mg/ml) in combination with and in comparison to aspirin on platelet function and activation in healthy subjects. METHODS AND RESULTS On separate test days in a crossover design, 16 healthy adults consumed aspirin (81 mg), cocoa (as a beverage), or aspirin plus cocoa. Platelet activation was measured by surface expression of P-selectin and PAC-1 binding to the activated conformation of the GPIIb/IIIa receptor (GPIIb/IIIa-act). Platelet function was measured on an analyzer (the PFA-100) that measures shear stress-induced platelet plug formation in response to collagen-epinephrine or collagen-ADP. Plasma epicatechin concentrations peaked approximately 2 h after subjects were given either the cocoa or aspirin plus cocoa. After 6 h, cocoa inhibited epinephrine-induced platelet function. Epinephrine-induced platelet function was inhibited 2 and 6 h after aspirin, and after aspirin plus cocoa. Epinephrine-stimulated P-selectin expression was inhibited by aspirin at 6 h, and after 2 and 6 h by aspirin plus cocoa. ADP-stimulated P-selectin expression was not affected by the treatments. Cocoa and aspirin, given separately, reduced epinephrine-stimulated GPIIb/IIIa-act expression at 2 and 6 h, respectively, and at 2 and 6 h when given together, suggesting an additive effective. ASA plus cocoa inhibited ADP-stimulated GPIIb/IIIa-act expression at 6 h. CONCLUSIONS Flavanol-rich cocoa inhibited epinephrine-stimulated platelet activation and function. These effects were qualitatively similar to aspirin, but less profound. These results emphasize the need to further examine the effects of food flavonoids for platelet modulating effects.

Cocoa and Wine Polyphenols Modulate Platelet Activation and Function

There is speculation that dietary polyphenols can provide cardioprotective effects due to direct antioxidant or antithrombotic mechanisms. We report in vitro and postingestion ex vivo effects of cocoa procyanidins, a procyanidin-rich cocoa beverage and dealcoholized red wine (DRW) on human platelet activation. In a series of in vitro studies, cocoa procyanidin trimers, pentamers or DRW (3 and 10 micromol/L) were incubated with citrated peripheral whole blood in the presence and absence of platelet agonists. Platelet activation was detected using fluorescent-labeled monoclonal antibodies recognizing the fibrinogen binding conformation of GPIIb-IIIa (referred to herein as PAC-1 binding) and the activation-dependent platelet epitope CD62P (P-selectin). The percentage of CD42a-positive platelets coexpressing PAC-1 binding and/or CD62P was determined by multiparameter flow cytometry. Procyanidin trimers, pentamers and DRW added to whole blood in vitro increased PAC-1 binding and P-selectin expression. In contrast, procyanidin trimers, pentamers and DRW inhibited the platelet activation in response to epinephrine. The effects on platelet activation of cocoa beverage and DRW consumption were also studied in healthy subjects. Citrated blood was obtained before and 2 and 6 h after the ingestion of a cocoa beverage, a caffeine-containing beverage, DRW or water. Platelet activation was measured by flow cytometry. The consumption of DRW did not affect the expression of activation-dependent platelet antigens, either unstimulated or after ex vivo activation with epinephrine. However, the consumption of DRW increased PAC-1 binding in response to 100 micromol/L ADP ex vivo. Cocoa consumption reduced platelet response to agonists ex vivo. The ingestion of water had no effect on platelet activation, whereas a caffeine-containing beverage augmented the response of platelets to epinephrine. In summary, select cocoa procyanidins and DRW added to whole blood in vitro increased expression of platelet activation markers in unstimulated platelets but suppressed the platelet activation response to epinephrine. In contrast, cocoa consumption suppressed unstimulated and stimulated platelet activation in whole blood. This suppressive effect observed on platelet reactivity may explain in part the reported cardioprotective effects of dietary polyphenols.

Platelet activation and platelet-erythrocyte aggregates in patients with sickle cell anemia

Vascular occlusion and vasculopathy underlie much of the morbidity in patients with sickle cell anemia. Platelets may play a role in this vasculopathy. Samples from 12 adults patients with sickle cell anemia were examined for evidence of platelet activation and formation of platelet-erythrocyte aggregates (PEA) using fluorescent-labeled monoclonal antibodies and flow cytometry. We noted an increased expression of activation-dependent antigens on the platelets from patients with sickle cell anemia compared with those from both white and black control subjects. In addition, patients with sickle cell anemia had increased levels of platelet microparticles and PEA. Platelets are activated in patients with sickle cell anemia and they adhere to sickle erythrocytes. The significance of this activation and adherence are the subject of further investigation.

Platelet activation in patients with sickle cell disease

Vascular occlusion and vasculopathy underlie much of the morbidity in patients with sickle cell anaemia. Platelets may play a role in this vasculopathy. Samples from 43 patients with sickle cell disease (SCD) were examined for evidence of platelet activation using fluorescent‐labelled monoclonal antibodies and flow cytometry. There was increased expression of activation‐dependent antigens on the platelets from patients with SCD compared to those from both Caucasian and African‐American controls. In addition, SCD patients had increased levels of platelet microparticles. Platelets are activated in patients with sickle cell disease. The contribution of platelet activation to sickle cell pathophysiology is under active investigation in our laboratories.

High-level long-term white blood cell microchimerism after transfusion of leukoreduced blood components to patients resuscitated after severe traumatic injury

BACKGROUND: Long‐term white blood cell (WBC) microchimerism (MC), of at least 2 years, has been reported in trauma patients receiving fresh nonleukoreduced (non‐LR) blood. It is unknown, however, whether this occurs with LR blood products that are nearly devoid of WBCs. Twenty‐seven patients transfused with LR and non‐LR blood products were studied after severe traumatic injury. A secondary aim was to explore donor‐recipient mixed lymphocyte reactivity in vitro.

Postprandial Lipemia is Associated With Platelet and Monocyte Activation and Increased Monocyte Cytokine Expression in Normolipemic Men

The activation of platelets and monocytes has been implicated in the development of cardiovascular diseases. We asked the question if postprandial lipemia following a fatcontaining meal is associated with platelet and monocyte activation and increased platelet-monocyte interaction. Thirteen healthy, normal weight, normolipemic males, 20 to 49 years, consumed a 40% fat meal of whole foods. Blood samples were obtained at fasting and 3½ and 6 hours after ingestion. Triglyceride levels increased to 48% over baseline at 3½ hours postconsumption and returned to fasting levels by 6 hours. Multiparameter flow cytometry using monoclonal antibodies showed that the percentage of platelets expressing surface P-selectin and the activated conformation the GPIIb-IIIa receptor was significantly higher at 3½ hours compared to fasting. The percentage of platelet-monocyte aggregates increased by 36% at 3½ hours and 43% at 6 hours postconsumption. The percentage of monocytes expressing intracellular tumor necrosis factor-tx (TNF-ax) increased seven and eightfold at 3½ and 6 hours, respectively. The expression of interleukin-l,B (IL-1p increased in a similar manner. These data suggest activation of platelets and monocytes after a moderate fat meal. Repetitive activation of platelets and monocytes could be an early event in the initiation and development of atherosclerosis.

Blood transfusion is associated with donor leukocyte microchimerism in trauma patients.

INTRODUCTION Blood transfusion can result in survival of donor leukocyte subpopulations in the recipient. Persistence of donor leukocytes in the transfusion recipient is termed microchimerism. Microchimerism likely reflects engraftment of the recipient with donor hematopoietic stem cells and is very uncommon with transfusion for elective surgery, sickle cell anemia, thalassemia, and HIV. We have found, however, that microchimerism may be more common in trauma patients. OBJECTIVE To determine how frequently transfusion after trauma is associated with microchimerism. METHODS We prospectively enrolled 45 trauma patients who were transfused > or =2 units of PRBCs. We sampled blood before hospital discharge and determined microchimerism by polymerase chain reaction (PCR) analysis of specimens using quantitative allele-specific HLA DR assays to detect non-recipient alleles. Data are expressed as median with interquartile range. RESULTS Patients had a median age of 38 (interquartile range 25, 58) years, ISS of 19 (13, 29), and mortality of 7%. Seventy-eight percent were men, and 84% had blunt trauma. Patients received a median of 6 (4, 16) (range 2, 87) units of PRBCs. Of the 45 patients, 24 (53%) had evidence of microchimerism. Compared with patients without evidence of microchimerism, these patients had no difference in mean age, gender, ISS, units of PRBCs transfused, time from transfusion to blood sampling, or proportion that underwent splenectomy. Twenty-one of the 24 patients with microchimerism had only 1 or 2 non-recipient DR alleles identified by PCR. CONCLUSIONS Transfusion after trauma is associated with over half of recipients having evidence of microchimerism. Age, sex, ISS, and splenectomy of the recipient and the number of transfused units did not correlate with microchimerism. Because the median time from transfusion to sampling for PCR analysis was not longer in the group without microchimerism, it is unlikely microchimerism is due merely to failure of the recipient to clear transfused donor leukocytes.

Flavanols and platelet reactivity.

Platelet activity and platelet-endothelial cell interactions are important in the acute development of thrombosis, as well as in the pathogenesis of cardiovascular disease. An increasing number of foods have been reported to have platelet-inhibitory actions, and research with a number of flavanol-rich foods, including, grape juice, cocoa and chocolate, suggests that these foods may provide some protection against thrombosis. In the present report, we review a series of in vivo studies on the effects of flavanol-rich cocoa and chocolate on platelet activation and platelet-dependent primary hemostasis. Consumption of flavanol-rich cocoa inhibited several measures of platelet activity including, epinephrine- and ADP-induced glycoprotein (GP) IIb/IIIa and P-Selectin expression, platelet microparticle formation, and epinephrine-collagen and ADP-collagen induced primary hemostasis. The epinephrine-induced inhibitory effects on GP IIb/IIIa and primary hemostasis were similar to, though less robust than those associated with the use of low dose (81 mg) aspirin. These data, coupled with information from other studies, support the concept that flavanols present in cocoa and chocolate can modulate platelet function through a multitude of pathways.