Utility of adsorption techniques in serological evaluation of warm autoimmune haemolytic anaemia

Background

Various adsorption techniques are available to remove serum autoantibodies and subsequently detect the underlying alloantibody in previously transfused patients with autoimmune haemolytic anaemia. We planned to establish a suitable adsorption technique in our transfusion service which can remove all autoantibodies and detect underlying alloantibodies rapidly, cheaply and effectively.

Study design and methods

We evaluated 71 direct antiglobulin test-reactive patients with warm AIHA over a period of 20 months. Twenty-three of these 71 patients who had a previous history of blood transfusion or pregnancy and were confirmed carriers of autoantibodies (indirect antiglobulin test-reactive) were considered for the adsorption study. Depending on the adequacy of samples, history of blood transfusion and severity of anaemia either autoadsorption or alloadsorption or both using polyethylene glycol (PEG) or low ionic strength saline (LISS)-papain were performed.

Results

Underlying alloantibodies were detected in 7 of the 23 patients (30.4%) and all these were specific to Rhesus antigens. The mean number of alloadsorptions for complete autoantibody removal using PEG was 1.43 which was significantly lower than the 3.9 using the LISS-papain method (p<0.05). The mean time required by PEG alloadsorption and LISS-papain alloadsorption for autoantibody removal was 93.6 minutes and 177.7 minutes, respectively (p<0.05). Discordant results were not observed in any case and identical alloantibodies were detected by both the techniques.

Conclusion

We found that the PEG method is a rapid, cheap and effective way to remove autoantibodies and detect underlying alloantibodies.     

Precautions surrounding blood transfusion in autoimmune haemolytic anaemias are overestimated

Background

It is very evident that many precautions are taken regarding transfusion of red blood cells in patients with autoimmune haemolytic anaemia. Frequently, considerable efforts are made to examine the indication and serological compatibility prior to transfusion in such patients. However, at times, this may unnecessarily jeopardize patients who urgently require a red blood cell transfusion.

Materials and methods

Thirty-six patients with warm-type autoimmune haemolytic anaemia were included in this study. All patients had reactive serum autoantibodies and required blood transfusion. Standard serological assays were employed for the detection and characterization of antibodies to red blood cells.

Results

A positive direct antiglobulin test was observed in all 36 patients, in addition to detectable antibodies in both the eluate and serum. Significant alloantibodies were detected in the serum samples of three patients (anti-c, anti-JK^a, and anti-E). In 32 patients, red blood cell transfusion was administered with no significant haemolytic transfusion reactions due to auto- and/or allo-antibodies. Due to overestimation of positive cross-matches three patients received no transfusion or delayed transfusion and died, and one patient died due to unrecognised blood loss and anaemia which was attributed to an ineffective red blood cell transfusion.

Discussion

Many of the reported recommendations regarding transfusion of red blood cells in autoimmune haemolytic anaemia are highly questionable, and positive serological cross-matches should not result in a delay or refusal of necessary blood transfusions.     

The role of the direct antiglobulin test in pre-transfusion investigations and the approach to selecting blood for transfusion in autoimmune haemolytic anaemia: results of a regional survey

Introduction

The aim of this study was to conduct a Regional survey to determine the policies and ways of performing the direct antiglobulin test in pre-transfusion screening, the approach used in cases giving positive results with this test and the technical and operative modalities for choosing blood for transfusion in cases of autoimmune haemolytic anaemia.

Materials and methods

A questionnaire, containing ten multiple-choice questions, was sent to all the transfusion centres in the Region of Tuscany.

Results

The data from all 40 regional centres were analysed. Direct antiglobulin tests and autocontrols were not regularly used in pre-transfusion screening. The direct antiglobulin test was predominantly reserved for suspected cases of autoimmune haemolytic anaemia. Sixty percent of the laboratories characterised the specificity of samples that were positive for IgG and complement by the direct antiglobulin test, 45% that were positive for IgM, 35% also for IgA, and 13% also for subclasses of IgG. Elution studies were reserved (in 18% of laboratories) for those cases in which it was expected that transfusion therapy would be used. In cases of autoimmune haemolytic anaemia, autologous/allogeneic adsorption was carried out in 27% of the structures (the use of proteolytic enzymes is predominant, followed by the “ZZAP” reagent – a mixture of dithiothreitol and an enzyme) and the dilution method in 20%; transfusion of red blood cells with a phenotype extensively compatible (c, C, D, E, e, K, Jk^a, Jk^b, Fy^a, Fy^b, S, s) with that of the recipient is practised in 17% of the centres, while transfusion of units of “least incompatible” red blood cells was reported by 95% of the centres, but in 88% this is preceded by at least one of the above mentioned immunohaematological investigations.

Conclusions

The organisation of a network of Services of Immunohaematology and Transfusion Medicine can be exploited to overcome some technical and operative limitations of peripheral, dependent Transfusion Sections. The results of this study reveal which immunohaematology laboratory is endowed with the greatest potential and which could, therefore, become the regional reference centre. This investigation could lay the basis for defining behavioural algorithms and recommendations on the issues considered.     

Significance of multiple types of antibodies on red blood cells of patients with positive direct antiglobulin test: a study of monospecific antiglobulin reactions in 85 patients

Blood samples from 85 patients with a positive direct antiglobulin test were tested with monospecific antiglobulin reagents: anti-IgG, anti-IgM, anti-IgA, and anti-C3. No typical pattern of antiglobulin reaction could be correlated with specific diseases except for the patients with methyldopa-induced positive direct antiglobulin test, all of whom had only IgG on their red blood cells. The presence of more than 1 type of antibody on red blood cells was associated with severe haemolysis. These patients responded less frequently to steroids, and in most of them no underlying disease could be found. Most patients with complement alone on red blood cells had no evidence of haemolysis, and when present it was never severe.     

The Direct Antiglobulin Test: Still a Place for the Tube Technique?

OBJECTIVES: Antibodies of different immunoglobulin isotypes, or complement, may coat red blood cells in vivo. They are detected by the direct antiglobulin test (DAT), usually performed by the conventional tube technique. The purpose of this study was to compare the latter technique with the gel test. METHODS: Three hundred and ninety-eight consecutive samples, sent to our laboratory for direct antiglobulin testing, were analyzed with the tube technique and the gel test, using reagents from different manufacturers. Eighty-seven samples had been collected from newborns and 23 from fetuses. Results were expressed as positive or negative. RESULTS: In 162 out of 398 cases, the DAT was negative with both methods, whereas in 178 out of 398 cases, the DAT was positive with both techniques using polyspecific antibodies (observed agreement: 84.5%; kappa = 0.71). Discrepancies between the two methods were observed in 58 cases: 51 samples appeared as DAT positive using the tube method and negative with the gel test, whereas only 7 were positive exclusively with the gel test. Among the 178 samples that were positive with both techniques, 93 samples showed discordant results when evaluated with monospecific antisera (11 with anti-IgG and 82 with anti-C3d, respectively). The sensitivity of the DAT performed by the gel test, in comparison with the conventional tube technique, was 75.4% (95% confidence interval (CI): 69.4-80.8). 96. 8% (95% CI: 92.8-99.0), and 16.3% (95% CI: 9.8-24.9) with polyspecific, anti-IgG and anti-Cd3 reagents, respectively. CONCLUSIONS: The gel test appeared to be less sensitive than the conventional tube technique when utilized for DAT, particularly when C3d was present on red blood cells. These results emphasize that before implementing a new technique in the laboratory, comparison with existing techniques, using different reagents, is mandatory.     

New insights into childhood autoimmune hemolytic anemia: a French national observational study of 265 children

Background

Autoimmune hemolytic anemia is a rare condition in children. Little is known about its initial presentation and the subsequent progression of the disease.

Design and Methods

Since 2004, a national observational study has been aiming to thoroughly describe cases and identify prognostic factors. Patients from all French hematologic pediatric units have been included if they had a hemoglobin concentration less than 11 g/dL, a positive direct antiglobulin test and hemolysis. Evans’ syndrome was defined by the association of autoimmune hemolytic anemia and immunological thrombocytopenic purpura. Data from patients’ medical records were registered from birth to last follow-up. Autoimmune hemolytic anemia was classified as primary or secondary. Remission criteria, qualifying the status of anemia at last follow-up, were used with the aim of identifying a subgroup with a favorable prognosis in continuous complete remission.

Results

The first 265 patients had a median age of 3.8 years at diagnosis. In 74% of cases the direct antiglobulin test was IgG/IgG+C3d. Consanguinity was reported in 8% of cases and first degree familial immunological diseases in 15% of cases. Evans’ syndrome was diagnosed in 37% of cases. Autoimmune hemolytic anemia was post-infectious in 10%, immunological in 53% and primary in 37% of cases. After a median follow-up of 3 years, 4% of children had died, 28% were still treatment-dependent and 39% were in continuous complete remission. In multivariate analysis, IgG and IgG+C3d direct antiglobulin tests were associated with a lower rate of survival with continuous complete remission (adjusted hazard ratio, 0.43; 95% confidence interval, 0.21–0.86).

Conclusions

This nationwide French cohort is the largest reported study of childhood autoimmune hemolytic anemia. The rarity of this condition is confirmed. Subgroups with genetic predisposition and underlying immune disorders were identified.     

An original method to study autoantibody specificity in haemoglobin stained eluates by the column agglutination techniques

Summary When studying autoantibody specificity by the indirect antiglobulin test with column agglutination techniques ether and xylene elution techniques result in haemoglobin stained eluates which give a red colouration to the gel or glass beads and do not allow the identification of positive reactions. Xylene eluates were incubated with commercially available group 0-test red cell panels at 37°C for 45 min in the wells of a microtitre plate in a 3:1 eluate:red cell ratio. After washing with normal saline, sensitized red cells, resuspended in low ionic strength solution (LISS), were applied onto the microtubes containing the antiglobulin serum and positive reactions were recorded after centrifugation. We studied the specificity of 35 autoantibody containing eluates from 12 patients with lymphoproliferative disorders (six having autoimmune haemolysis) and 23 HIV patients without autoimmune haemolysis. All patients had a gel or column positive (IgG) direct antiglobulin test while the tube direct antiglobulin test failed to show red cell bound IgG. We found a reactive indirect antiglobulin test in 20/23 eluates from HIV infected patients (with a panreactive specificity), in all patients with autoimmune haemolysis (one with anti-C, two with anti-E, one with anti-K and two with a panreactive specificity) and in all patients with positive direct antiglobulin test but without immune mediate haemolysis (in all cases with panreactive specificity). The method proposed is a promising tool for the study of the specificity of antibody containing haemoglobin stained eluates; in this study it allowed us to confirm that some HIV patients have specific binding of IgG on their RBC and to identify the specificity of tube test non-reactive eluates.     

Prevalence,specificity and risk of red blood cell alloantibodies among hospitalised Hubei Han Chinese patients

Background

The prevalence, specificity and risk of red blood cell alloantibodies vary widely among different geographic areas, races, and diseases and according to different methods of study, but no data are available on the Chinese Han population, who were investigated in the present study.

Materials and methods

Antibody screening was conducted among 42,517 hospitalised Hubei Han Chinese individuals using column agglutination technology. Samples that were positive in antibody screening were subjected to antibody identification by the tube test. Clinical data, including gender, age, race, transfusion history and records of alloantibody detection, transfusion reactions or haemolytic disease of the newborn, were collected to analyse the prevalence and specificity of alloantibodies and complications associated with them.

Results

A total of 212 patients with alloantibodies were identified among 42,517 patients, yielding a prevalence of 0.50% in this study. Significantly different prevalence rates were observed according to age and sex. The most frequently identified alloantibodies were anti-E (87/212, 41.0%), anti-D (45/212, 21.2%), anti-M (41/212, 19.3%) and a combination of anti-E and anti-c (13/212, 6.1%). Haemolytic disease was observed in 13 infants with anti-D, three infants with anti-E and one infant with anti-Fy^a alloantibodies. Delayed haemolytic transfusion reactions occurred in four patients with alloantibodies.

Discussion

In hospitalised Hubei Han Chinese individuals, the overall prevalence of alloantibodies was 0.50%, with anti-E, anti-D and anti-M being the most frequently identified alloantibodies. These results indicate that anti-D and anti-E alloantibodies were major risk factors for haemolytic disease of the newborn or delayed haemolytic transfusion reactions in this study population.     

Relationship of Circulating Anti-C3b and Anti-C1q IgG to Lupus Nephritis and Its Flare

Background and objectives

Autoantibodies to complement C1q (anti-C1q) are associated with the diagnosis of lupus nephritis. In this study, we compare anti-C1q IgG with another complement autoantibody, anti-C3b IgG, as a biomarker of lupus nephritis and lupus nephritis flare.

Design, setting, participants, & measurements

Our investigation involved the Ohio SLE Study, a prospective observational cohort of patients with recurrently active lupus who were followed bimonthly. Serum anti-C1q and anti-C3b IgG levels were assessed cross-sectionally by ELISA in 40 normal controls and 114 patients in the Ohio SLE Study (41 nonrenal and 73 lupus nephritis) at study entry, and longitudinally in a subset of patients in the Ohio SLE Study with anti-C1q–positive lupus nephritis in samples collected every 2 months for 8 months leading up to lupus nephritis flare (n=16 patients).

Results

In the cross-sectional analysis, compared with anti-C1q IgG, anti-C3b IgG was less sensitive (36% versus 63%) but more specific (98% versus 71%) for lupus nephritis. Only anti-C3b IgG was associated with patients with lupus nephritis who experienced at least one lupus nephritis flare during the Ohio SLE Study period (P<0.01). In the longitudinal analysis, circulating levels of anti-C1q IgG increased at the time of lupus nephritis flare only in patients who were anti-C3b positive (P=0.02), with significant increases occurring from 6 (38% increase) and 4 months (41% increase) before flare. Anti-C3b IgG levels also trended up at lupus nephritis flare, although the change did not reach statistical significance (P=0.07). Neither autoantibody increased 2 months before flare.

Conclusions

Although not as prevalent as anti-C1q IgG, anti-C3b IgG showed nearly complete specificity for lupus nephritis. The presence of anti-C3b IgG identified patients with lupus nephritis who were prone to flare and in whom serial measurements of markers associated with complement, such as anti-C1q IgG, may be useful to monitor lupus nephritis activity.     

Jk(a?b?) phenotype screening by the urea lysis test in Thai blood donors

Background

The Jk(a−b−) phenotype is rare in most populations and often detected after transfusion or pregnancy. After immunisation, anti-Jk3 forms and it can be difficult to find compatible Jk(a−b−) donors. Using anti-Jk^a and anti-Jk^b in a conventional tube method is unsuitable for identifying Jk(a−b−) in mass screening of blood donors. Jk(a−b−) phenotypes are associated with the absence of urea transporters on erythrocytes, making red blood cells (RBC) resistant to lysis by 2M urea, while Jk(a+b−), Jk(a−b+) and Jk(a+b+) phenotypes are susceptible to lysis.

Materials and methods.

We screened for Jk(a−b−) phenotypes in blood donors by the urea lysis test using a 96-well microplate. The Jk(a−b−) phenotypes were confirmed by the indirect antiglobulin test (IAT).

Results

Altogether, 20,163 blood samples from Thai blood donors were tested and only RBC from five samples were resistant to lysis by 2M urea, while 20,158 samples were completely lysed within 5 min. In an IAT, both anti-Jk^a and anti-Jk^b failed to agglutinate RBC from all five samples. Using a micro-titre plate, the direct urea lysis test, costs • 0.01, about 480 times less than IAT. Moreover, the test time for each plate (94 samples) is about 18 times less than that for IAT.

Conclusion

Jk(a−b−) phenotype screening by the direct urea lysis test on samples in a micro-titre plate is simple, cost-effective and practical for mass screening of blood donors.     

Monitoring compliance with transfusion guidelines in hospital departments by electronic data capture

Background

The practice of transfusing red blood cells is still liberal in some centres suggesting a lack of compliance with guidelines recommending transfusion of red blood cells at haemoglobin levels of 6–8 g/dL in the non-bleeding patient. Few databases provide ongoing feedback of data on pre-transfusion haemoglobin levels at the departmental level. In a tertiary care hospital, no such data were produced before this study. Our aim was to establish a Patient Blood Management database based on electronic data capture in order to monitor compliance with transfusion guidelines at departmental and hospital levels.

Materials and methods

Hospital data on admissions, diagnoses and surgical procedures were used to define the populations of patients. Data on haemoglobin measurements and red blood cell transfusions were used to calculate pre-transfusion haemoglobin, percentage of transfused patients and transfusion volumes.

Results

The model dataset include 33,587 admissions, of which 10% had received at least one unit of red blood cells. Haemoglobin measurements preceded 96.7% of the units transfused. The median pre-transfusion haemoglobin was 8.9 g/dL (interquartile range 8.2–9.7) at the hospital level. In only 6.5% of the cases, transfusion was initiated at 7.3 g/dL or lower as recommended by the Danish national transfusion guideline. In 27% of the cases, transfusion was initiated when the haemoglobin level was 9.3 g/dL or higher, which is not recommended. A median of two units was transfused per transfusion episode and per hospital admission. Transfusion practice was more liberal in surgical and intensive care units than in medical departments.

Discussion

We described pre-transfusion haemoglobin levels, transfusion rates and volumes at hospital and departmental levels, and in surgical subpopulations. Initial data revealed an extensive liberal practice and low compliance with national transfusion guidelines, and identified wards in need of intervention.     

The UK National External Quality Assessment Scheme in Blood Group Serology. ABO and D grouping, antibody screening, direct antiglobulin test and antibody identification 1984-1985

In seven exercises of blood grouping the overall rates of major error were 0.19% and 0.25% in ABO and D grouping respectively. In ABO grouping this represents an increase in error rate over that observed in 1982-1983 but the increase was due to an unusually high error rate with one particular group A2B cell. An improvement in performance was observed in simple D grouping and was largely due to a lower incidence of false positive grouping of D-negative cells in the antiglobulin test. An improvement in performance observed in D grouping IgG-coated D-negative cells appeared to be due to a better understanding of the problem rather than to any change in serological practice. Error rates in antibody screening were somewhat lower than in 1982-1983 but this may or may not represent an improvement in performance as the test materials were not the same in the two periods. The direct antiglobulin test with IgG-coated cells was reliably performed with polyspecific and with anti-IgG reagents but an excess of false positive results was obtained with anti-C3d. Error rates in antibody identification varied from 0.6% for anti-D to 74% for anti-c + E.     

Efficacy of Performing Red-Cell Antibody Elutions in Patients with a Positive Direct Antiglobulin Test

Red blood cell antibody elutions are often routinely performed whenever a positive direct antiglobulin test (DAT) is encountered. To evaluate the efficacy of performing routine red-cell elutions we reviewed our antibody elution data. Of 122 eluates, 83 were negative, 35 were warm panagglutinins, 2 were felt to be transfusion-induced alloantibodies, 1 was passively acquired anti-A, and 1 was inconclusive. One of the eluted alloantibodies was not demonstrable in the serum. Thus, only 1 (0.8%) of the eluates provided important information not readily available through serum testing alone. We conclude that extensive serologic evaluation of a positive DAT should be reserved for those patients who have been recently transfused or are suspected of having immune hemolysis.     

Increased detection of clinically significant antibodies and decreased incidence of delayed haemolytic transfusion reaction with the indirect antiglobulin test potentiated by polyethylene glycol compared to albumin: a Japanese study

Background

The indirect antiglobulin test (IAT) can be potentiated by agents such as polyethylene glycol (PEG-IAT) and albumin (Alb-IAT). PEG-IAT is generally regarded as superior to Alb-IAT for the detection of clinically significant red blood cell (RBC) antibodies. However, supporting data come from Caucasian-dominant populations. Non-Caucasian populations should be investigated as well.

Material and methods

In this single-centre, retrospective, sequential study, Alb-IAT was used from 1989 to 1996 (8 years) and PEG-IAT from 1997 to 2008 (12 years). Pre-transfusion RBC alloantibody detection rates and specificity, post-transfusion alloantibody production, and the incidence of delayed haemolytic transfusion reaction were assessed and compared for the two periods.

Results

Although overall RBC alloantibody detection rates were comparable, PEG-IAT more frequently detected clinically significant antibodies such as anti-E, anti-Fy^b, and anti-Jk^a, and less frequently detected insignificant antibodies such as anti-Le^b and anti-P₁. New alloantibodies emerged comparably during the two periods. Delayed haemolytic transfusion reaction was less frequent during the PEG-IAT period (0.30% versus 0.12%, p<0.05).

Conclusion

PEG-IAT was superior in the detection of clinically significant antibodies, reduced the detection of insignificant antibodies, and prevented delayed haemolytic transfusion reaction better than Alb-IAT among Japanese transfusion recipients in this retrospective survey of limited power.     

Management of complaints in blood establishments: thirteen years of experience at the Croatian Institute of Transfusion Medicine

Background.

The aim of the study is to present the results and experience in the management of complaints in a transfusion service in order to draw attention to the importance of this segment of quality management and to stimulate publication of other studies on the topic.

Materials and methods.

This study is based on data from the Croatian Institute of Transfusion Medicine obtained by analysis of complaints recorded during a 13-year period (1998–2010). The distribution of the types and frequencies of complaints is presented, along with the level of their justifiability and criticality. The dynamics of the complaints is analysed overall and within particular categories. In addition, corrective actions and other factors that may have influenced the trends observed are discussed.

Results.

During the study period, 817 complaints were received, most of which (40.9%) referred to the positive direct antiglobulin test in red cell concentrates, followed by blood product issuing and distribution (12.9%) and blood product quality (9.4%). Of the 817 complaints, 177 (21.7%) were assessed as serious and 645 (78.9%) as justified based on the testing performed.

Conclusion.

Data collected by systematic recording and analysis of complaints provide a basis for problem identification, implementation of corrective and preventive actions, and improvement of product and service quality, and, thereby, customer satisfaction.     

A comparison of two automated methods for the detection and identification of red blood cell alloantibodies

Background

The aim of this study was to compare the routine use of two automated systems (OrthoAutoVue Innova, microcolumn, and Immucor Galileo, solid phase) for the screening and identification of irregular red blood cell alloantibodies in samples, analysed in our Transfusion Service during 6 months of normal activity. The study focused particularly on an evaluation of the repeatability of the screening tests, the identification of antibody specificities and the identification of antibodies in samples showing discordant results.

Materials and methods

Overall 2,229 samples from potential blood donors (A), multiply transfused patients with blood disorders (DH), potential transfusion recipients (TS), and external cases (E) were studied. The protocols were carried out according to the manufacturers recommendations.

Results

The screening tests detected 78 samples that were positive with both systems, while 18 were positive only with Immucor and 11 only with Ortho (thus, overall, Immucor detected 96 positive samples and Ortho 89 positive samples). The use of the respective identification panels enabled us to identify the antibodies in 65 samples with Immucor and in 61 samples with the Ortho system; 74 antibodies were identified with Immucor (55 with a single specificity and 19 with mixed specificities) and 68 antibodies with Ortho (51 and 17, respectively). In the remaining cases (31 samples for Immucor and 28 for Ortho), the antibody specificity was not identified. The two systems were found to be essentially similar. The Immucor system revealed a greater number of antibodies, mainly because of its greater sensitivity at detecting anti-D antibodies.

Conclusions

Both systems showed a repeatability of over 85%, demonstrating that automation of immunohaematological tests is advantageous. The specificity of the antibody was identified in 68% of the samples. Furthermore, using the two systems led to the identification of ten new antibodies (6 anti-D, 2 anti-E, 1 anti Le^a, and 1 anti-Vel), which would not have been detected had only one of the two methods been used.     

The prevalence of irregular erythrocyte antibodies among antenatal women in Delhi

Background

Universal screening of all antenatal women, including D antigen-positive pregnant ones, is mandatory in most developed countries. However, no guidelines on this issue are available for developing countries such as India. Furthermore, there is limited information on immunisation rates in pregnant women (D antigen-positive and D antigen-negative) from India. We, therefore, studied the prevalence of alloantibodies among multigravida women in India.

Materials and methods

In this prospective study, carried out to detect the prevalence of alloantibodies among multigravida women in India, 3,577 multigravida women attending antenatal clinics were typed for ABO and D antigens and screened for alloantibodies by column agglutination technology. The medical history and detailed obstetric history of these women were reviewed and information recorded on any prior haemolytic disease of the foetus and newborn among siblings and/or blood transfusions.

Results

The overall prevalence of alloantibodies in this study was 1.25%. There was a statistically significant difference between alloimmunisation rates in the D antigen-negative and D antigen-positive groups (10.7% versus 0.12%, respectively). Anti-D antibody contributed to 78.4% of total alloimmunisations in our study.

Discussion

Anti-D was the most common culprit responsible for alloimmunisation. Other alloantibodies found included anti-C, anti-M, anti-S and anti-c. Large-scale population-based studies are required to assess the real magnitude of alloimmunisation in pregnant women in India.     

Incidence of Red Cell Alloantibody among the Transfusion Recipients of Universiti Kebangsaan Malaysia Medical Centre

Red blood cell alloimmunization is a common complication among the transfusion recipients. In Malaysia, multiple ethnicity causes genetic heterogeneity among the population which in turn can cause a wide variation of antibody. The objective of this study was to analyse the red cell alloantibody detected during the pre-transfusion testing. This was a cross-sectional study done in the blood bank of Universiti Kebangsaan Malaysia Medical Centre during the period of January–December 2010. The data was retrieved from the hospital laboratory information system. A total of 24,263 patients’ blood samples were subjected for pre-transfusion testing. Antibody screening was done using an indirect antiglobulin test method. The positive samples were further identified for antibody specificity. Antibody screening tests were positive in 184 patients out of 24,263 samples with the incidence of 0.76 %. Autoantibodies and alloantibodies were detected in 39/184 (21.2 %) and 140/184 (76.1 %) of the patients respectively. In five patients (2.7 %) the antibody specificity remained undetermined. Total 161 alloantibodies were identified. The suspected Anti-Mia alloantibody was observed most frequently (49/161, 30.4 %) followed by anti-E (30/161, 18.6 %) and anti-D (22/161, 13.7 %). Anti-E and anti-c were the most common combination of multiple alloantibodies. In view of the high incidence of suspected Anti-Mia antibodies, more efforts are needed to look into the techniques for confirmation of the Anti-Mia antibodies. Besides that, we suggested that all multiply transfused patients should be phenotyped for the Rh system and to supply Rh phenotype specific blood in order to limit alloimmunization.     

General Practitioners’ Judgment of their Elderly Patients’ Cognitive Status

Background

General practitioners (GP) play an important role in detecting cognitive impairment among their patients.

Objectives

To explore factors associated with GPs’ judgment of their elderly patients’ cognitive status.

Design

Cross-sectional data from an observational cohort study (AgeCoDe study); General practice surgeries in six German metropolitan study centers; home visits by interviewers.

Participants

138 GPs, 3,181 patients (80.13 ± 3.61 years, 65.23% female).

Measurements

General practitioner questionnaire for each patient: familiarity with the patient, patient morbidity, judgment of cognitive status. Home visits by trained interviewers: sociodemographic and clinical data, psychometric test performance. Multivariate regression analysis was used to identify independent associations with the GPs’ judgment of “cognitively impaired” vs. “cognitively unimpaired.”

Results

Less familiar patients (adjusted odds ratio [aOR] 2.42, 95% CI 1.35–4.32, for poor vs. very high familiarity), less mobile patients (aOR 1.29, 95% CI 1.13–1.46), patients with impaired hearing (aOR 5.46, 95% CI 2.35–12.67 for serious vs. no problems), and patients with greater comorbidity (aOR 1.15, 95% CI 1.08–1.22) were more likely to be rated as “cognitively impaired” by their GPs.

Conclusions

The associations between GPs’ assessments of cognitive impairment and their familiarity with their patients and patients’ mobility, hearing, and morbidity provide important insights into how GPs make their judgments.KEY WORDS: general practice, cognition, dementia, clinical judgment     

Multiple domains of ADAMTS13 are targeted by autoantibodies against ADAMTS13 in patients with acquired idiopathic thrombotic thrombocytopenic purpura

Background

Type G immunoglobulins against ADAMTS13 are the primary cause of acquired (idiopathic) thrombotic thrombocytopenic purpura. However, the domains of ADAMTS13 which the type G anti-ADAMT13 immunoglobulins target have not been investigated in a large cohort of patients with thrombotic thrombocytopenic purpura.

Design and Methods

Sixty-seven patients with acquired idiopathic thrombotic thrombocytopenic purpura were prospectively collected from three major U.S. centers. An enzyme-linked immunosorbent assay determined plasma concentrations of anti-ADAMTS13 type G immunoglobulins, whereas immunoprecipitation plus western blotting determined the binding domains of these type G immunoglobulins.

Results

Plasma anti-ADAMTS13 type G immunoglobulins from 67 patients all bound full-length ADAMTS13 and a variant truncated after the eighth TSP1 repeat (delCUB). Approximately 97% (65/67) of patients harbored type G immunoglobulins targeted against a variant truncated after the spacer domain (MDTCS). However, only 12% of patients’ samples reacted with a variant lacking the Cys-rich and spacer domains (MDT). In addition, approximately 37%, 31%, and 46% of patients’ type G immunoglobulins interacted with the ADAMTS13 fragment containing TSP1 2-8 repeats (T2-8), CUB domains, and TSP1 5-8 repeats plus CUB domains (T5-8CUB), respectively. The presence of type G immunoglobulins targeted against the T2-8 and/or CUB domains was inversely correlated with the patients’ platelet counts on admission.

Conclusions

This multicenter study further demonstrated that the multiple domains of ADAMTS13, particularly the Cys-rich and spacer domains, are frequently targeted by anti-ADAMTS13 type G immunoglobulins in patients with acquired (idiopathic) thrombotic thrombocytopenic purpura. Our data shed more light on the pathogenesis of acquired thrombotic thrombocytopenic purpura and provide further rationales for adjunctive immunotherapy.