Positive direct antiglobulin test due to antiphospholipid antibodies in normal healthy blood donors

Antiphospholipid Antibodies and Autoimmune Haemolytic Anaemia: A Systematic Review and Meta-Analysis

The relationship between antiphospholipid antibodies (aPL) and autoimmune haemolytic anaemia (AIHA) has never been systematically addressed. The aim of this study is to assess the link between aPL and AIHA in adult systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). This study performed an EMBASE/PubMed search from inception to June 2019 and meta-analysis using Peto’s odds ratios. The pooled prevalence (PP) of IgG/IgM anticardiolipin (aCL) and lupus anticoagulant (LA) was greater in AIHA +ve than AIHA −ve patients (34.7% vs. 27.6%, p = 0.03; 33.3% vs. 21.8%, p < 0.0001; 20.9% vs. 8.3%, p = 0.01). The PP of AIHA was greater in: (1) IgG and IgM aCL +ve than −ve patients (21.8% vs. 11.1%, p = 0.001 and 18.7% vs. 6.3%, p < 0.0001), (2) in SLE related APS than in primary APS patients (22.8% vs. 3.9% p < 0.0001), (3) in APS +ve than APS −ve SLE patients (23.2% vs. 8.4%, p = 0.01), and (4) in thrombotic APS than non-thrombotic APS/SLE patients (26.8% vs. 10%, p = 0.03). The PP of IgG/IgM aCL and LA was greater in DAT +ve than DAT −ve patients (42.4% vs. 12.8%, p < 0.0001; 26.2% vs. 12.8%, p = 0.03 and 29.2% vs. 15.7%, p = 0.004 respectively). It was found that AIHA prevalence is maximal in SLE with aPL/APS, low-moderate in SLE without aPL and minimal in PAPS. Moreover, AIHA is rightly included among the classification criteria for SLE but not for APS/aPL. The significance of an isolated DAT positivity remains unclear in this setting

Band 3 ectopic expression in colorectal cancer induces an increase in erythrocyte membrane-bound IgG and may cause immune-related anemia

Autoimmune hemolytic anemia (AIHA) is a rare comorbidity in colorectal cancer (CRC) and has an unknown etiology. Previously, we described an AIHA case secondary to CRC with ectopic band 3 expression. Herein, we investigated ectopic band 3 expression and erythrocyte membrane-bound IgG in a CRC cohort. Between September 2016 and August 2018, 50 patients with CRC and 26 healthy controls were enrolled in the present study. The expression of band 3 and SLC4A1 mRNA was observed in 97% of CRC surgical specimens. Although clinical AIHA was not observed in any patient with CRC, a direct antiglobulin test was positive in 10 of the patients in the CRC group (p = 0.01). Flow cytometry revealed significantly increased erythrocyte membrane-bound IgG among patients with CRC compared to healthy controls (mean ± standard deviation; 38.8 ± 4.7 vs. 29.9 ± 15.6, p = 0.012). Normocytic anemia was observed, including in cases negative for fecal occult blood, suggesting a shortened erythrocyte life-span due to increased membrane-bound IgG. Immunoprecipitation revealed increased anti-band 3 autoantibodies in patients' sera. Mouse experiments recapitulated this phenomenon. We also confirmed that band 3 expression is controlled by 5'AMP-activated protein kinase under hypoxic conditions. These findings increase our understanding of the etiology of cancer-related anemia.

Association of a positive direct antiglobulin test with chronic immune thrombocytopenia and use of second line therapies in children: A multi-institutional review

Immune thrombocytopenia (ITP) is the most common autoimmune cytopenia in children. Approximately, 25% of patients develop chronic disease, which may be unpredictable and challenging to treat. It is not currently possible to predict at the time of presentation which patients will have chronic disease or will experience symptoms requiring second-line therapy defined as treatment beyond corticosteroids, intravenous immunoglobulin, or Rh immune globulin. A multi-institutional retrospective review of 311 pediatric patients with ITP was performed with the goal of identifying clinical characteristics associated with disease course. In a cohort of 216 patients tested and for whom disease status was known, a positive direct antiglobulin test (DAT) was associated with chronic ITP vs spontaneous resolution of disease (29.2% vs 8.1%, P < 0.001) as well as the need for treatment with second line agents (38.5% vs 11.4%, P < 0.001) in 241 patients. Controlling for the effect of Evans syndrome, defined as having two immune cytopenias, a positive DAT was independently associated with chronic ITP (OR = 2.7, 95% CI: 1.0-7.2, P = 0.041) and use of second-line agents (OR: 3.6, 95% CI: 1.7-7.7, P = 0.001) by multivariate logistic regression model. These findings demonstrate an association with positive DAT and chronic disease, as well as refractory disease requiring second-line agents.

The Differences Between Childhood and Adult Onset Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is a rare autoimmune disease of unknown etiology that represents a leading cause of acquired thromboembolism and recurrent miscarriage. It is characterized by the persistent elevated presence of pathogenic antiphospholipid auto-antibodies directed against cardiolipin, ß2-glycoprotein-I, and/or a positive lupus anticoagulant test. As with many autoimmune disorders, the pathogenesis of APS is believed to be the result of a complex interaction between environmental triggers and genetic predisposition. Although more common in adults, APS occasionally manifests in the neonatal period and throughout childhood. Adut-onset APS classification criteria are poorly validated to the pediatric population (in which pregnancy related complications are seldom seen) and as a result, assessment of the prevalence of the disease in childhood is difficult. Thromboembolic events seen in children include deep venous thrombosis in addition to stroke and pulmonary embolism, which can lead to significant long-term disability. The disease can be classified as either primary (when occurring in isolation) or secondary, in which the disease is diagnosed in the context of another underlying disease, most commonly systemic lupus erythematosus. A variety of laboratory and clinical difference are seen between pediatric and adult-onset APS. The marked female predominance seen in adult-onset disease is less evident in childhood where the gender split is more evenly spread. In addition, children with APS are at a higher risk of recurrent thromboembolism than adults. The treatment of childhood-onset APS is challenging due to a lack of large-scale prospective studies in the pediatric population. Therapeutic options are often based upon treatment guidelines that have been based upon literature from the adult-onset form of the disease. In the majority of cases, treatment is focused on the prevention of further thrombosis through treatment with long-term anti-coagulation therapy. The evidence for the use of antiplatelet agents (such as aspirin) and hydroxychloroquine is inconclusive. It is important to remember that anti-coagulation can have significant lifestyle implications for the child with APS and it is essential to consider potential implications relating to school and recreational activities, with contact sports often discouraged due to the increased risk of bleeding.

Incidence of clinically significant antibodies in patients and healthy blood donors: a prospective cross-sectional study from a tertiary healthcare center in India

INTRODUCTION

Since there is scarce data available on incidence and type of irregular antibodies in patients and donors in India, a study was undertaken to find the incidence of irregular antibodies in patients and irregular antibodies and a positive Direct Antiglobulin Test (DAT) in blood donors.

MATERIALS AND METHODS

Antibody screening was performed using commercial pooled "O" cells and three-cell panel for donors and patients respectively and an 11-cell panel for identification using Column Agglutination Technology (CAT) with Low-Ionic-Strength Saline-Indirect Antiglobulin Test (LISS-IAT) technique (Ortho Clinical Diagnostics, Johnson & Johnson, USA). The cassettes used were Anti-human Globulin (AHG) type. DAT on donors was also performed using the AHG cassettes.

RESULTS

Cumulative incidence of irregular antibodies amongst patients (n=32,560) and donors (n=31,367) were 0.12-0.009%, respectively. In patients, the commonest antibodies were from Rh system with anti-D being the most common antibody type (14/40; 35%) while in donors it was the MNS system with anti M (2/3) being the most common. Incidence of a positive DAT amongst the healthy blood donors was 0.04% (n=13/32,560).

DISCUSSION

Incidence of irregular antibodies in patients at 0.12% was slightly lower than published reports and could be because of the fact that the patient population studied comprised largely of surgical patients many of whom have never received blood transfusion. This data could also be more representative since the number of patients studied was much higher as compared to the previous Indian studies (32,560 vs. 531-2026). The report on incidence of irregular antibodies and DAT (0.009-0.04%) in blood donors was first such attempt in India.

Management of blood donors and blood donations from individuals found to have a positive direct antiglobulin test

The medical literature is replete with articles addressing the diagnosis and management of patients with a positive direct antiglobulin test (DAT). However, there is scant information addressing the management of blood donors and blood donations found to have a positive DAT. Practices vary considerably between countries and blood suppliers within countries, and there is no standardized approach to the management of these blood donors or the blood products prepared from their donations. Recent evidence from Israel suggests that the finding of a positive DAT in a blood donor may not be as benign as previously thought. Therefore, it may be prudent for blood collection agencies to periodically reexamine their approach to the management of blood donors with a positive DAT and their donations. This article reviews the available literature and explores options for the management of DAT-positive blood donors and their blood donations.

A newly recognized blood group in domestic shorthair cats: the Mik red cell antigen

BACKGROUND

Naturally occurring alloantibodies produced against A and B red cell antigens in cats can cause acute hemolytic transfusion reactions. Blood incompatibilities, unrelated to the AB blood group system, have also been suspected after blood transfusions through routine crossmatch testing or as a result of hemolytic transfusion reactions.

HYPOTHESIS

Incompatible crossmatch results among AB compatible cats signify the presence of a naturally occurring alloantibody against a newly identified blood antigen in a group of previously never transfused blood donor cats. The associated alloantibody is clinically important based upon a hemolytic transfusion reaction after inadvertent transfusion of red cells expressing this red cell antigen in a feline renal transplant recipient that lacks this red cell antigen.

METHODS

Blood donor and nonblood donor cats were evaluated for the presence of auto- and alloantibodies using direct antiglobulin and crossmatch tests, respectively, and were blood typed for AB blood group status. Both standard tube and novel gel column techniques were used.

RESULTS

Plasma from 3 of 65 cats and 1 feline renal transplant recipient caused incompatible crossmatch test results with AB compatible erythrocytes indicating these cats formed an alloantibody against a red cell antigen they lack, termed Mik. The 3 donors and the renal transplant recipient were crossmatch-compatible with one another. Tube and gel column crossmatch test results were similar.

CONCLUSIONS AND CLINICAL IMPORTANCE

The absence of this novel Mik red cell antigen can be associated with naturally occurring anti-Mik alloantibodies and can elicit an acute hemolytic transfusion reaction after an AB-matched blood transfusion.

Use of gel microcolumn assay for the detection of drug-induced positive direct antiglobulin tests

Drugs can result in broad variety of hematologic abnormalities including positive direct antiglobulin test. In this study, we evaluated gel microcolumn assay for the detection of drug-induced antibodies. Direct antiglobulin test was performed by conventional tube and by gel microcolumn assay in 139 hospitalized patients. Drug in vitro studies were done in 34 patients with positive direct antiglobulin test by tube test and gel microcolumn assay using serum and eluate. None of them had signs of hemolytic anemia. A total of 1,000 blood samples from donors were used as control group. Gel microcolumn assay was more sensitive than in tube test for direct antiglobulin test (P<0.01). Positive direct antiglobulin test was more frequent in patients than in donors (P<0.01). Drug in vitro studies were positive with at least one drug in 76.5% of patients with positive direct antiglobulin test by immune complex and/or adsorption mechanisms. We found a high incidence of positive drug in vitro tests in positive direct antiglobulin test patients. Gel microcolumn assay showed appropriate results for drug in vitro studies. The combination of tube and gel microcolumn assay can improve detection of drug-induced positive direct antiglobulin tests.

Comparison of conventional tube test technique and gel microcolumn assay for direct antiglobulin test: a large study

Gel microcolumn assay (GMA) is a modified serological technique that has been used for ABO and Rh typing, direct antiglobulin test (DAT), detecting alloantibodies, red cell phenotyping, and other applications. However, for DAT, the role of GMA is controversial. The purpose of this large study was to compare the performance of the conventional tube test (CTT) to GMA for detecting potentially significant antibodies coating red blood cells in vivo. From January 1996 to May 2002, we performed DATs by GMA and CTT on 9,862 blood samples submitted to our reference laboratory, using LISS/Coombs cards (DiaMed-Latino America, Lagoa Santa-MG, Brazil) for GMA and polyspecific and monospecific anti-IgG reagents for CTT. Acid eluates were prepared from all positive DAT samples. The specificity of eluates was determined by GMA. We detected nonconcordant results in 2,079 out of 3,163 positive DATs (65.7%). All of these tests were only positive in GMA. Sensitivity and specificity for DATs was 100% and 83.0% for gel, and 50.7% and 97.8% for tube, respectively. Based on this study GMA showed to be more sensitive than CTT for detecting potentially significant antibodies coating red blood cells in vivo.