Noemi Greppi

Effectiveness of Red Blood Cells Filtered Through Cotton Wool to Prevent Antileukocyte Antibody Production in Multitransfused Patients

Abstract. The effectiveness of red blood cells made leukocyte‐free by filtration through cotton wool to prevent the production of antileukocyte antibodies was evaluated in children suffering from Cooleys anemia. Two studies were performed: study I was carried out prospectively in two groups of non transfused patients, one group treated with leukocyte‐free filtered red cells, the other with buffy‐coat‐free packed red cell units. Different types of antileukocyte antibodies were looked for in both groups and the results were compared. In study II the behavior of pre‐existing lymphocytotoxic antibodies found in the serum of children previously transfused with standard or buffy‐coat‐free packed red cell units was followed after the patients had been passed to a program of transfusion with leukocyte‐free filtered red cells. Study I showed that none of the patients transfused with leukocyte‐free filtered red cell units have produced antileukocyte antibodies, while these could be found in 2/3 of the patients transfused with buffy‐coat‐free packed red cell units. Study II showed that the repeated transfusion of leukocyte‐free filtered red cells to patients who possessed in their serum preformed lymphocytotoxic antibodies did not cause any increase in the potency or spectrum of these antibodies, but was in fact accompanied in some cases by their decrease or disappearance. It is concluded that filtration through cotton wool is an easy and inexpensive means of preparing leukocyte‐free red blood cells for transfusion capable of preventing (or reducing) the production of antileukocyte antibodies in multitransfused patients.

Metformin overdose causes platelet mitochondrial dysfunction in humans

IntroductionWe have recently demonstrated that metformin intoxication causes mitochondrial dysfunction in several porcine tissues, including platelets. The aim of the present work was to clarify whether it also causes mitochondrial dysfunction (and secondary lactate overproduction) in human platelets, in vitro and ex vivo.MethodsHuman platelets were incubated for 72 hours with saline or increasing doses of metformin (in vitro experiments). Lactate production, respiratory chain complex activities (spectrophotometry), mitochondrial membrane potential (flow-cytometry after staining with JC-1) and oxygen consumption (Clark-type electrode) were then measured. Platelets were also obtained from ten patients with lactic acidosis (arterial pH 6.97 ± 0.18 and lactate 16 ± 7 mmol/L) due to accidental metformin intoxication (serum drug level 32 ± 14 mg/L) and ten healthy volunteers of similar sex and age. Respiratory chain complex activities were measured as above (ex vivo experiments).ResultsIn vitro, metformin dose-dependently increased lactate production (P < 0.001), decreased respiratory chain complex I activity (P = 0.009), mitochondrial membrane potential (P = 0.003) and oxygen consumption (P < 0.001) of human platelets. Ex vivo, platelets taken from intoxicated patients had significantly lower complex I (P = 0.045) and complex IV (P < 0.001) activity compared to controls.ConclusionsDepending on dose, metformin can cause mitochondrial dysfunction and lactate overproduction in human platelets in vitro and, possibly, in vivo.Trial registrationNCT%2000942123.

The clinical importance of leukocyte depletion in regular erythrocyte transfusions.

Abstract. Antilymphocyte, antigranulocyte and antiplatelet alloantibodies, T lymphocyte subsets, expression of HLA‐DR antigens on T lymphocytes and NK cell function were determined in 11 homozygous β‐thalassemic children multitransfused ab initio with Erypur‐filtered leukocyte‐free red cell units (group A) and in 13 similar children multitransfused with standard packed red cell units (group B). No antibodies were found in group A patients, whereas 69% of group B patients were immunized. The two groups did not differ significantly with regard to the other test results. Considered together, thalassemia patients showed a percentage of T4+ cells and a NK cell function that were significantly lower than those found in a reference group of 16 healthy male blood donors. Thalassemics moreover showed a higher than normal percentage of T3+, T4+ and T8+ cells expressing HLA‐DR antigens.

Relationship of the time of storage and transfusion reactions to platelet concentrates from buffy coats

BACKGROUND: Transfusion reactions to platelet concentrates prepared from buffy coats (BC‐PCs) were reviewed to determine the effect of some variables of BC‐PC preparation and storage: time of BC storage before BC‐PC preparation (1–2 days); time of BC‐PC storage before transfusion (1–5 days); no white cell reduction versus laboratory and bedside BC‐PC white cell reduction.

Optimal conditions for white cell reduction in red cells by filtration at the patient's bedside

Background: A quality control program of white cell (WBC) reduction in red cells at the bedside was implemented, based on postfiltration counting in a Nageotte chamber of the residual WBCs from samples taken from a segment of the transfusion set, after 1‐in‐10 sample dilution with Turkss solution. During a 1‐year quality control program, 5.1 percent of counted units had apparent filtration failures, that is, WBC counts exceeding 5 × 106 per unit. The cause(s) for these apparent failures were investigated.

Outcomes of an automated procedure for the selection of effective platelets for patients refractory to random donors based on cross-matching locally available platelet products.

In 1999, we implemented an automated platelet cross‐matching (XM) programme to select compatible platelets from the local inventory for patients refractory to random donor platelets. In this study, we evaluated platelet count increments in 40 consecutive refractory patients (8·3% of 480 consecutive platelet recipients) given 569 cross‐match‐negative platelets between April 1999 and December 2001. XM was performed automatically with a commercially available immunoadherence assay. Pre‐, 1‐ and 24‐h post‐transfusion platelet counts (mean ± SD) for the 569 XM‐negative platelet transfusions containing 302 ± 71 × 109 platelets were 7·7 ± 5·5, 32·0 ± 21·0 and 16·8 ± 15·5 × 109/l respectively. Increments were significantly higher (P < 0·05, t‐test) than those observed in the same patients given 303 random platelet pools (dose = 318 ± 52 × 109 platelets) during the month before refractoriness was detected, when pre‐, 1‐ and 24‐h post‐transfusion counts were 7·0 ± 8·6, 15·9 ± 16·1 and 9·6 ± 12·8 × 109/l respectively. The cost of the platelet XM disposable kit per transfusion to produce 1‐h post‐transfusion platelet count increments >10 × 109/l was euro 447. This programme enabled the rapid selection of effective platelets for refractory patients, from the local inventory.

Preliminary evaluation of cord blood platelet gel for the treatment of skin lesions in children with dystrophic epidermolysis bullosa

The common clinical manifestations of EB are mechanical fragility of the skin, blister formation, and abnormal wound healing, but the severity of the skin lesions varies depending on the distinct type of the disease. Junctional EB and dystrophic EB (DEB), the most severe types of EB diseases, usually cause chronic pain and discomfort that can significantly reduce the quality of life of affected

Multicenter evaluation of a whole-blood filter that saves platelets

BACKGROUND:  Whole‐blood (WB) leukoreduction filters in current use retain the majority of PLTs. A new whole‐blood filter, which retains significantly fewer of the PLTs (or saves PLTs [WB‐SP]), has been developed. The performance characteristics of the WB‐SP filter have been evaluated in a multicenter study.

Multicentre standardisation of a clinical grade procedure for the preparation of allogeneic platelet concentrates from umbilical cord blood.

BACKGROUND In addition to a largely prevalent use for bleeding prophylaxis, platelet concentrates from adult blood have also been used for many years to prepare platelet gels for the repair of topical skin ulcers. Platelet gel can be obtained by activation of fresh, cryopreserved, autologous or allogeneic platelet concentrates with calcium gluconate, thrombin and/or batroxobin. The high content of tissue regenerative factors in cord blood platelets and the widespread availability of allogeneic cord blood units generously donated for haematopoietic transplant but unsuitable for this use solely because of low haematopoietic stem cell content prompted us to develop a national programme to standardise the production of allogeneic cryopreserved cord blood platelet concentrates (CBPC) suitable for later preparation of clinical-grade cord blood platelet gel. MATERIALS AND METHODS Cord blood units collected at public banks with total nucleated cell counts <1.5×10(9), platelet count >150×10(9)/L and volume >50 mL, underwent soft centrifugation within 48 hours of collection. Platelet-rich plasma was centrifuged at high speed to obtain a CBPC with target platelet concentration of 800-1,200×10(9)/L, which was cryopreserved, without cryoprotectant, below -40 °C. RESULTS During 14 months, 13 banks produced 1,080 CBPC with mean (± standard deviation) volume of 11.4±4.4 mL and platelet concentration of 1,003±229×10(9)/L. Total platelet count per CBPC was 11.3±4.9×10(9). Platelet recovery from cord blood was 47.7±17.8%. About one-third of cord blood units donated for haematopoietic transplant could meet the requirements for preparation of CBPC. The cost of preparation was € 160.92/CBPC. About 2 hours were needed for one technician to prepare four CBPC. DISCUSSION This study yielded valuable scientific and operational information regarding the development of clinical trials using allogeneic CBPC.

The ‘cherry buffy‐coat syndrome’, a cause of decreased platelet yield in platelet concentrates obtained from buffy‐coats

A large number of European blood centres, including our own, use the buffy‐coat method for platelet production. In this article we describe a previously unnoticed phenomenon shown by a proportion of buffy‐coats, which display an unusually bright cherry colour and low platelet counts.