Fernanda Morelati

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.

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.

In vitro quantification of anti-red blood cell antibody production in idiopathic autoimmune haemolytic anaemia: effect of mitogen and cytokine stimulation

The immunopathogenic mechanisms underlying idiopathic autoimmune haemolytic anaemia (AIHA) are still unknown, although regulatory cytokines are thought to play an important role. We investigated cytokine production by mitogen‐stimulated whole blood cultures from 21 patients with AIHA and from 22 age‐ and sex‐matched controls. In parallel experiments, we studied the effect of mitogen and cytokine stimulation on anti‐red blood cell (RBC) IgG antibody production, assessed as both binding on autologous RBCs and secretion in culture supernatants. To quantify anti‐RBC antibody, we set up a sensitive and quantitative solid phase competitive immunoassay. The results showed that in AIHA patients production of interleukin (IL)‐4, IL‐6 and IL‐13 was significantly increased, whereas that of interferon (IFN)‐γ was reduced. Multivariate analysis showed that IFN‐γ was the only independent factor significantly associated with the reduced T‐helper‐1‐like cytokine profile. Patients with active haemolysis showed further reduction of IFN‐γ and IL‐2 production and increased secretion of transforming growth factor (TGF)‐β. In AIHA patients, mitogen stimulation, as well as IL‐6, significantly increased autologous anti‐RBC‐binding relative to unstimulated cultures. Mitogen stimulation and addition of IL‐4, IL‐6, IL‐10, IL‐13 and TGF‐β significantly increased both autologous anti‐RBC binding and antibody secretion in AIHA patients compared with controls. The results suggest that a reduced T‐helper‐1‐ and a predominant T‐helper‐2‐like profile and elevated TGF‐β levels might play a role in the immunopathogenesis of AIHA. Furthermore, our competitive anti‐RBC antibody was able to detect anti‐RBC antibody production in some direct antiglobulin test (DAT)‐negative AIHA patients.

Management of alloimmune thrombocytopenia

Fetal alloimmune thrombocytopenia is caused by maternal sensitization to paternally-derived antigens on fetal platelets, most commonly HPA-1a.1 It occurs in approximately 1 in 1000 live births and is the commonest cause of severe fetal and neonatal thrombocytopenia, and of intracranial hemorrhage in neonates born at term.2 Since there is currently no routine screening, first-time cases of fetal alloimmune thrombocytopenia are generally identified following the birth of a markedly thrombocytopenic neonate. Antenatal management is thus only possible in subsequent pregnancies. Intracranial hemorrhage is the most devastating complication of fetal alloimmune thrombocytopenia and often occurs antenatally. Assessment of projected clinical severity is thus based on the development of intracranial hemorrhage in a previous sibling. If there is such a history of intracranial hemorrhage, the chance of this complication occurring again in the next pregnancy is extremely high in an untreated, antigen-positive sibling.3 Administration of intravenous immunoglobulin (IVIG) to the mother, initially given in conjunction with dexamethasone, was first used to prevent recurrence of antenatal intracranial hemorrhage in 1988.4 This approach of providing IVIG-based medical therapy administered to the mother to increase the fetal platelet count has since been extensively investigated in hundreds of maternal-fetal pairs.5 The efficacy of IVIG-based therapy has been supported by numerous studies6–16 (Table 1A) but not by others17–19 (Table 1B). The studies presented in Tables 1A and 1B surprisingly report virtually identical percentages of cases of intracranial hemorrhage: 2.7% versus 2.9%, respectively. However, overall mean birth platelet counts differed markedly between the two groups. While platelet counts are considered to be surrogate markers of intracranial hemorrhage, fortunately, the likelihood of fetal and neonatal intracranial hemorrhage, in the absence of this complication having occurred in a previous sibling, is relatively low.

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.

Evaluation of a new automated instrument for pretransfusion testing

BACKGROUND: A number of automated devices for pretransfusion testing have recently become available. This study evaluated a fully automated device based on column agglutination technology (AutoVue System, Ortho, Raritan, NJ).

Immune hemolytic anemia associated with teicoplanin

BACKGROUND:  Several drugs can cause immune hemolytic anemia. Here a patient who developed hemolytic anemia after treatment with teicoplanin is described.

An acute haemolytic transfusion reaction due to anti-Jk.

The Kidd system antibodies are characteristically difficult to detect. They show variability in immunoglobulin class, subclass and serological characteristics. They are generally detected by an antiglobulin test, using a polyspecific antiglobulin or complement antiserum. Often, the antibodies are only detected using cells with a double dose (homozygous) expression of Kidd antigens, enzyme-treated cells or by using sensitive immunohaematological techniques.

New technologies in immunohaematology.

Since the discovery of the ABO system, numerous important innovations have contributed to a continuous, rapid evolution in the diagnostic methods for in vitro measurements of the antigen-antibody reaction, allowing a significant improvement in the compatibility between blood from donors and the recipients. Apart from the introduction of ABO typing, these methods include the determination of Rh type and phenotype, the direct and indirect antiglobulin tests, cross-matching and consequent identification of antigens and antibodies of clinical relevance, the use of low ionic strength additives and enzyme treatments, the development of monoclonal reagents and solid-phase and microcolumn platforms for performing the pre-transfusion tests. Since transfusion safety depends on a series of strictly inter-related processes1, among which pre-transfusion tests have a predominant role, in recent years some of the new technologies that integrate the classical techniques in immunohaematology have become valid instruments for improving the safety of transfusions. The aim of this review is to illustrate the principles and practical applications of these emerging techniques used in our laboratory to identify antigens and antibodies, in cases of red cell or platelet immunisation.