A. Parravicini

Red cell alloantibodies in thalassemia major. Results of an Italian cooperative study

Clinical and serological data on 1435 Italian thalassemia major patients were collected during a cooperative study involving 19 centers in 10 regions. The main findings were as follows: 18 percent of the patients were under 6 years of age, 63 percent between 6 and 15, and 19 percent over 15. Forty‐one percent had undergone splenectomy. Sixty‐two percent of the patients were maintained at pretransfusion hemoglobin levels higher than 10 g per dl, 36 percent between 8 and 10 g per dl, and 2 percent below 8 g per dl. Overall, 5.2 percent of the patients had clinically significant red cell alloantibodies (136 alloantibodies in 74 patients). One‐half of the immunized patients had more than one and one‐fourth had more than two alloantibodies. The specificities of the 136 alloantibodies were almost exclusively confined to the common antigens of the Rh, Kell, Kidd, and Duffy systems, in that decreasing order of frequency. The antibody screening procedure, using a low‐ionic‐ strength solution antiglobulin test against a three‐red‐cell panel and the patients own red cells (autocontrol) with a serum to cell ratio of 100 to 1 was shown to be an adequate technique for red cell antibody detection.

Prevalence of hepatitis C virus antibodies in Italian blood donors.

Abstract. 11,117 blood donors from 24 blood transfusion services evenly distributed throughout the various Italian regions were tested for the presence of hepatitis C virus (HCV) antibodies in the serum and serum alanine aminotransferase (ALT) level. The results are as follows: (1) anti‐HCV seroprevalence in Italy was 0.87% with a difference between Northern and Southern regions (0.68 vs. 1.37%) and between younger and older subjects (0.62 vs. 1.21%); (2) prevalence of elevated ALT levels was 4.74% without a North‐South effect (except than for markedly elevated ALT levels); (3) anti‐HCV seroprevalence was higher in subjects with elevated ALT (5.0%), with a North‐South effect (2.2 vs. 9.9%) and particularly high (19.2%) in subjects with markedly elevated ALT; (4) ALT levels were elevated in 26.2% of anti‐HCV positive subjects, with a North‐South effect (14 vs. 40.5%).

Leukocyte depletion of red cell units at the bedside by transfusion through a new filter

Standard packed red cell (PRC) units can be depleted of leukocytes and platelets if they are transfused through a blood administration set in which the usual 170‐mu filter has been replaced by a leukocyte removal filter (Sepacell R‐500). During a 6‐month period, 1550 PRC units were transfused through this filter in 611 transfusions to 80 multitransfused patients with thalassemia who had had a patient reaction rate (PRR) of 63 percent and a transfusion reaction rate (TRR) of 13 percent when given standard PRC or buffy‐coat‐depleted PRC. When given filtered PRC, PRR and TRR became 3.7 percent and 0.5 percent, respectively. The effectiveness of the filter was also evaluated in vitro. By filtering 2 standard PRC units through the same filter, median values (and ranges) for red cell recovery and for residual leukocytes and platelets were 87 percent (83–92), 6.1 × 10(6) (0–100), and 2.7 × 10(9) (0.6–9.7), respectively. Although refinements are needed to improve standardization of the filter and to increase red cell recovery (which is low when 1 unit is filtered through one filter) and blood administration rate, the ability to provide leukocyte‐free red cells prepared at the bedside for virtually all recipients appears to be a realistic goal.

Removal of white cells from red cells by transfusion through a new filter

The effectiveness of a new filter (RC100) for the preparation of white cell‐depleted red cells (RBCs) at the bedside was evaluated in vitro and in vivo using three RBC products: standard RBC concentrate (CPDA units), RBCs suspended in saline‐adenine‐glucose‐mannitol additive solution after the removal of plasma (SAGM units), and RBCs suspended in SAGM after the removal of plasma and buffy coat (SAGM‐BC units). Median RBC recovery was at least 92 percent when 2 units were administered through one filter; median values for residual white cells and platelets were less than or equal to 20 × 10(6) and less than or equal to 2.5 × 10(9) per 2 units, respectively. The in vivo study was carried out in 80 multiply transfused patients with thalassemia, 35 of whom had experienced frequent nonhemolytic transfusion reactions when given standard or buffy coat‐free RBCs. During the 6‐month study, each patient was given two transfusions of each type of RBC product One febrile nonhemolytic transfusion reaction occurred in each of two patients receiving SAGM‐BC units, but in no other case. If the flow rate is not reduced, the median transfusion time is 35 minutes per CPDA unit and 15 minutes per SAGM and SAGM‐BC unit. It is concluded that the transfusion of RBCs through the RC100 is a simple and effective procedure to administer white cell‐depleted RBCs prepared at the bedside.

White cell-reduced red cells prepared by filtration : a critical evaluation of current filters and methods for counting residual white cells

White cell (WBC) reduction, red cell (RBC) recovery, and filtration time were determined in 1‐day‐old standard and buffy coat‐depleted RBCs filtered in the laboratory through six commercial filters for WBC reduction. Residual WBCs were counted with a Burker chamber (BC), with a Nageotte chamber (NC), and by flow cytometry (FC). Results show that BC counts were 0 in several cases in which WBCs were detected with NC and FC, which indicated that the traditional BC method is too insensitive in use with currently available filters. Calibration curves performed by FC and with NC with samples containing known concentrations of WBCs from 1000 to 1 per microL showed that both FC and NC detected, on average, 67 percent of WBCs present in the samples (efficiency). However, the efficiency of FC showed small variability (61–70%) at different WBC levels, whereas the variability with NC was large (39–91%). This greater variability prevented the correction of NC counts by using a single factor and indicated difficulty in NC standardization. Therefore, because our main aim was to compare different filters rather than to define absolute levels of WBC contamination, uncorrected FC and NC counts were chosen to be reported. True WBC counts per unit should not exceed values that can be obtained by dividing uncorrected counts by the lowest efficiencies (61% for FC and 39% for NC). Uncorrected NC and FC counts were below 2 × 106 per unit in all units processed through three of the filters and below 5 × 106 per unit in all units processed through the other three. Removal of the buffy coat from RBCs before filtration generally but not invariably caused slightly higher WBC removals. Median RBC recovery in CPD RBCs containing the buffy coat, filtered through four of the filters, was greater than 90 percent, which was significantly higher than that shown by the other two filters. Buffy coat removal prior to filtration involved an additional median loss of 12.4 percent of RBCs. Median filtration time ranged from 5 to 23 minutes per unit. Although NC appears to be less expensive than FC, its performance in experimental and routine conditions requires further evaluation and thorough standardization. Because of the continuous development of more effective filters, more sensitive methods for WBC counting in WBC‐reduced blood components are needed.

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.

Preparation of Leukocyte-Free Platelets for Transfusion by Filtration through Cotton Wool

Abstract. Filtration through Imugard filters of random platelet concentrates or platelets obtained by plateletpheresis allow the preparation of leukocyte‐free platelets for transfusion. The procedure is simple and determines only a small platelet loss (less than 10%). Filtered platelets seem to function normally in vivo. The use of leukocyte‐free red cell and platelet transfusions for the support of patients suffering from leukemia or aplastic anemia could prevent major complications, such as refractoriness to platelet transfusion and to bone marrow transplantation.

Quality assessment of transfusion practice in elective surgery

A program of quality assurance (QA) was adopted to improve blood transfusion practice in elective surgery at a large urban hospital. For this purpose, a cooperative multidisciplinary group was formed, key indicators were identified, and an organization was set up. Data collected by this organization in the 1‐year period needed for implementation of the program indicated that blood misuse was common practice. In fact, overrequest, overtransfusion, excessive reconstitution of whole blood (i.e., concurrent transfusion of red cells and fresh‐frozen plasma), and underuse of predeposit were found in all ten surgical departments of the hospital. In a pilot study, data were collected from one surgical department during and after the implementation phase of the QA program; comparison of these data showed a postimplementation reduction of about two thirds in overtransfusion, whereas overrequest, reconstitution of whole blood, and predeposit rates remained unchanged. These results prompted continuation of the program in order to reach a definitive evaluation of its effectiveness.

Evaluation of three procedures for the preparation of leukocyte-poor and leukocyte-free red blood cells for transfusion.

Abstract. Three methods of leukocyte deprivation of blood for transfusion have been evaluated. Filtration of relatively fresh packed red cells (up to 5 days old) through Erypur filters appears to be the method of choice for the preparation of leukocyte‐free red cells, used to prevent the production of antileukocyte antibodies in nonimmunized, nontransfused patients undergoing repeated blood transfusions. Double dextran sedimentation plus saline washings also yields leukocyte‐free red cells, although with a lower frequency, and represents an alternative to Erypur filtration, especially because of the lower cost and no need of special equipment. Imugard filtration appears to be a simple and effective way for preparing leukocyte‐poor red blood cells. For all the three procedures, results are definitely better when buffy coat‐free packed red cell units are processed. In a given hospital the choice of the technique(s) for the preparation of leukocyte‐poor (free) red blood cells for transfusion depends on a number of factors, such as type of patients to be transfused (immunized or nonimmunized, small children or boys and adults), aim of the procedure (prevention of the febrile transfusion reaction or prevention of antileukocyte antibody production), continuous availability of materials, cost, length and easiness of the procedure; these three latter parameters are in turn related to a number of local situations and facilities.

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.