Polyspecific Anti-human Globulin Research Articles

Role of direct antiglobulin test in assessing the severity of extravascular hemolysis in autoimmune hemolytic anemia – analysis from a cross-sectional study

Background: Autoimmune hemolytic anemia (AIHA) is an immune hemolytic disease characterized by hemolysis and anemia which results from increased red cell destruction due to auto antibodies directed against self-antigens on red cells. Clinical characteristics and potential associated hemolysis in AIHA can greatly depend on the serological characteristics. Aims and Objectives: This study was done to find out the association of Grade of polyspecific Direct Antiglobulin test (DAT), complement involvement and immunoglobulin G (IgG) subclass with severity of hemolysis in an AIHA patients. Materials and Methods: This was a cross-sectional study conducted for a period of 18 months from March 1, 2012, to August 31, 2013. Fifty consecutive AIHA patients diagnosed by a positive DAT in EDTA anticoagulated blood samples using poly specific anti human globulin reagent were followed up and results of various immunohematological tests such as polyspecific and monospecific DAT, IgG subtyping, and thermal amplitude were performed. Hematological and biochemical parameters such as hemoglobin, percentage of reticulocyte, total serum bilirubin, and serum lactate dehydrogenase also were recorded. Data were analyzed using SPSS v17. Results: Majority of patients were belonging to 31–40 year age group and there was a remarkable female predilection. Secondary AIHA was more common (56%) than primary. SLE was identified as the most common underlying disorder in secondary AIHA. Majority (46%) were Grade 4 DAT positive. Predominant autoantibody identified was IgG (52%). Of the total IgG positive cases, IgG1 was the predominant subclass. C3d alone was detected in 18% of cases and C3d and IgG together in 30%. About 48% of our patients were of warm type, 32% mixed type, and 20% cold type. About 80% of the study population were treated with steroids alone. A small percentage of cases (16%) needed immunosuppressant in addition to steroids and still a smaller percentage (4%) needed splenectomy. Higher grades of DAT positivity were associated with more severe degree of anemia and hyperbilirubinemia. The study also demonstrated a positive correlation between DAT grade and severity of hemolysis. Conclusion: AIHA patients in this study were predominantly of Warm AIHA with more of IgG1 involvement. A significant association is found between higher grades of DAT results and severity of anemia and jaundice in this study group. A positive correlation exists between grades of DCT and hemolysis as well.

Determination of C,c,E and e Antigens Section Prevalence in Rh D Negative Individuals: Is it Good Exercise with Utilities in Clinical Blood Transfusion Practices?

Introduction: Besides D antigen, C,c,E and e antigens of Rh blood group system are the most important antigens involved in alloimmunisation. The prevalence of C,c,E and e antigens in Rh D negative individuals in local population has many utilities in transfusion medicine practice. Aim: To determine the prevalence of C,c,E and e antigens in Rh D negative individuals. Materials and Methods: This prospective observational study was performed at Bhanumati clinical laboratory, Navsari, Gujarat, India, from January 2020 to January 2022. A total of 270 Rh D negative samples irrespective of ABO blood group status were typed for C,c,E and e antigen using monoclonal reagents from two different manufacturers using conventional tube technique. The most likely phenotype and genotype were determined using reference textbooks. Possibility of weak D in these 270 samples was ruled out using polyspecific Antihuman Globulin Reagent performing test for weak D antigens. Results were analysed using Excel spread sheet. Results: Prevalence of C,c,E, and e antigen in the 270 Rh D negative samples were, C (17, 6.29%), c (267, 98.88%), E (1, 0.37%) and e (270, 100%). Most probable genotypes were dce/ dce(rr), dCe/dce(r’r), dCe/dCe(r’r’) and dcE/dce(r’’r). Conclusion: Data obtained of C,c,E and e antigen prevalence in Rh D negative individuals is having varied utilities in blood transfusion services such as formulating rare blood group registry, preparing in house screening and panel red cells, and maintaining inventory of rare blood group units using freezing technology, if available.

CLINICAL AND LABORATORIAL FACTORS ASSOCIATED WITH HEMOLYTIC DISEASE SECONDARY TO ABO INCOMPATIBILITY IN A BRAZILIAN COHORT OF 4,122 NEWBORNS

ABO incompatibility affects up to 15% of mother and fetus binomial. Hemolysis secondary to ABO incompatibility is an important differential diagnosis among newborns presenting with jaundice. Most studies evaluating risk factors for newborn hemolysis due to ABO incompatibility date from almost 40 years ago and literature lacks reports describing the laboratorial factors predictive of this disease after the advent of modern immunohematological reagents, which are more sensitive. To determine the clinical and laboratorial factors associated with the occurrence of overt hemolysis due to ABO incompatibility among Brazilian newborns. This was a nested case control study stemming from a cohort of 4,122 newborns of three different Brazilian hospitals. Mothers and newborns were ABO typed using conventional tube method and direct antiglobulin test (DAT) was also performed in tube using polyspecific anti human globulin. The occurrence of jaundice secondary to ABO incompatibility was retrieved from the medical files. Diverse clinical and laboratorial factors were associated with the endpoint (ABO incompatibility disease) using Chi-square test for categorical variables and t-test for continuous variables. Multivariable analysis was performed using logistic regression. A p-value less than 0.05 was considered significant. Among the 4,122 newborns 44 had the diagnosis of hemolytic disease due to ABO incompatibility. The incidence of this complication was 7.9% considering only the situations in which there was ABO incompatibility between mother and fetus. Positive DAT, group O mother and group A newborn were significantly associated with the occurrence of clinical symptoms of hemolysis and this association was kept in multivariable model (p < 0.001 for the three variables). The presence of intra-uterine growth arrest, use of corticosteroids or antibiotics by the mother, type of birth (C-section or normal) and mother self-declared race were not associated with the occurrence of overt hemolysis secondary to ABO incompatibility. DAT presented 65.85% sensitivity, 96.28% specificity, 16.9% positive predictive value and 99.6% negative predictive value for the diagnosis of ABO incompatibility hemolysis. There were no cases of positive DAT in situations other than mother group O and newborns group A or B. The hemoglobin presented by the newborns right after birth was significantly lower when mothers were of group O and newborns were of group A (p < 0.001). Positive DAT, mother of group O and newborn of group A are independent factors associated with the occurrence of hemolysis due to ABO incompatibility of clinical relevance. With the improvement of the immunohematological reagents, positive DAT poses as an important diagnostic tool for the diagnosis of this complication, since the negative predictive value of the test is very high.

Serological Characterisation of Auto-antibodies in Patients with Direct Antiglobulin Test Positive Autoimmune Haemolytic Anaemia at a Tertiary Care Teaching Hospital in Tirupati, India

Introduction: Haemolysis in Autoimmune Haemolytic Anaemia (AIHA) is a result of Immunoglobulin G (IgG) or Immunoglobulin M (IgM) auto-antibodies with or without complement components binding to the Red Blood Cell (RBC) surface and initiating its destruction. Serologic evidence is provided by autocontrol or Direct Antiglobulin Test (DAT). Diagnostic work-up is essential as the management depends on the antibody type. Characteristics of the bound antibody and the target antigen determine the degree of haemolysis. Serological characterisation in AIHA helps to differentiate into its various types which help the clinician to decide on the treatment to be given. Aim: To serologically characterise the auto-antibodies in patients with DAT positive AIHA at a tertiary care teaching hospital. Materials and Methods: This cross-sectional study was carried out in the Department of Transfusion Medicine, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India, from March 2019 to February 2020. A 40 consecutive patient samples were included in the study. Characterisation of antibody was done using polyspecific Anti-Human Globulin (AHG) reagent followed by mono-specific AHG reagent by gel method. If antibody was of IgG type, then the subclass was determined by a mono specific anti-IgG1 and anti-IgG3 gel card. Association between antibody types, subtype, and strength of DAT with severity of haemolysis were compared using Chi-square/Fisher’s-exact test. A p-value of less than 0.05 was considered statistically significant. Results: The total study population was 40 patients. The mean age of the study population was 45 years (range 13-78). Out of 40 patients, males were 30 (75%) and females were 10 (25%). The primary and secondary causes for AIHA include 4 (10%) and 36 (90%) respectively. Among 40 patients, 22 (55%) patients had IgG antibody alone, 17 (42.5%) patients had IgG antibody with combination of other antibodies and 1 (2.5%) had only complement (C3d). IgG1 was identified in 7 (18%) of patients, combination of IgG1 and IgG3 in 3 (7.7%). There was a significant association with IgG+combination (p-value=0.03), IgG1+IgG3 (p-value=0.029) and strength of reaction (p-value=0.003) with respect to severity of haemolysis. Conclusion: Presence of multiple antibodies, presence of IgG1 and IgG3 and with complement combination and presence of higher grading of reaction in gel column were associated with severity of haemolysis. We recommend that serological characterisation of auto-antibody in AIHA would help the clinician in assessing the severity of haemolysis so that management can be done appropriately.

Autoimmune Haemolytic Anaemia in Patients with Cancer Diagnoses

Aims: To determine if AIHA plays a role in anaemia associated with malignancies, and ascertain the cancers in which AIHA occurs.&#x0D; Study Design: This was a cross-sectional case-control study.&#x0D; Place and Duration of Study: Department of Haematology and Blood Transfusion, University of Port Harcourt Teaching Hospital, Rivers, Nigeria.&#x0D; Methodology: We conducted the study on patients with malignancies either on admission in the wards or attending follow up clinics. Healthy age/sex-matched subjects were used as controls. Cases with and without chemotherapy were analyzed as subgroups. Three hundred and seventy-six (376) participants (188 cancer patients and 188 controls) were enrolled in the study. Full blood count, reticulocyte count, blood film, direct antiglobulin test (DAT), indirect antiglobulin test (IAT) and bilirubin assays were conducted on anticoagulated blood samples of all the patients and controls. The DAT was performed on a fresh sample not more than 6 hours after collection using polyspecific anti-human globulin.&#x0D; Results: Three (1.6%) of the 188 patients with malignancies were found to have a positive DAT of which 2 (1.1%) had strongly positive DAT with features of haemolysis and therefore had AIHA. The two patients with AIHA had chronic lymphocytic leukaemia. The third case was a weak positive DAT with malignant teratoma but did not have features of haemolysis. The cases of both AIHA and DAT were found in the group without chemotherapy. AIHA was the aetiology of anaemia in 2 (2%) of the 98 cases who had anaemia and were chemotherapy naive.&#x0D; Conclusion: AIHA plays a minor role in the aetiology of anaemia in cancer and is more common in lymphoid malignancies. A positive DAT may occur without features of haemolysis.

Agglutination testing for human erythrocyte product in the rhesus macaque.

There has been interest in using human blood products in nonhuman primate models of trauma to supplement human studies and to provide evidence to guide novel trauma resuscitation strategies. The compatibility of human RBCs has not been extensively studied in nonhuman primate species. Whole blood samples were collected from five healthy, nontransfused, not previously pregnant Chinese-bred rhesus macaques. The whole blood was centrifuged, and the plasma was decanted from each sample. Group O-negative human RBCs were mixed with the plasma from the rhesus macaque monkeys. Compatibility testing was performed by an immediate spin test and polyspecific and monospecific anti-human globulin (AHG) tests in glass tubes. Immediate spin testing revealed three out of five plasma samples (60%) from rhesus macaques caused at least 1+ agglutination with the human RBCs. Polyspecific anti-human globulin (AHG) tests demonstrated that two of five plasma samples (40%) from rhesus macaques caused at least 1+ agglutination with the human RBC, while the monospecific AHG testing revealed that the incompatibility was caused by C3d, not IgG. Human RBCs are not compatible with the plasma of some, but not all, Chinese-bred rhesus macaques.

A comparative study showing the potency of anti-C3d and anti-immunoglobulin G in polyspecific anti-human globulin using fresh and cryopreserved red blood cells.

BACKGROUND:The antiglobulin test is used to determine red blood cells (RBCs) having surface-bound immunoglobulin G (IgG) and/or complement (C3b, C3d, C4b, and C4d) free in serum or attached to antigens on RBCs. In such circumstances, the quality of the anti-human globulin (AHG) which is used in routine cross-match/indirect agglutination test plays a vital role in blood transfusion medicine. For potency testing of polyspecific AHG, it is recommended by the Food and Drug Administration and the Centre for Biologics Evaluation and Research to use fresh O +ve RBCs within 1 hr of collection for sensitization with anti-C3d.AIM AND OBJECTIVE:Freshly collected red cells were cryopreserved and stored at a temperature of −70°C for 30 days. These cells were then sensitized with C3d and IgG after deglycerolization. Their viability was checked by potency testing using polyspecific AHG-containing anti-C3d and anti-IgG.MATERIALS AND METHODS:Anonymous left over fresh whole blood samples were collected from the Indian Red Cross Society, New Delhi, with CPDA as an anticoagulant, and the samples were treated within 1 h of collection. ABO and Rh (D) phenotyping was performed by test tube method. RBCs and plasma from the same donor were used throughout the study.RESULTS:In this comparative study, fresh RBCs (O +ve) maintained their viability after cryopreservation and were also found to be suitable for sensitization with C3d and IgG. The potency of polyclonal AHG did not differ significantly with fresh RBCs and cryopreserved RBCs for 30 days.CONCLUSION:This result suggests that the sensitization of fresh RBCs with IgG and C3d is not affected by using cryopreserved cells for 30 days.

Maternal anti-M induced hemolytic disease of newborn followed by prolonged anemia in newborn twins

Allo-anti-M often has an immunoglobulin G (IgG) component but is rarely clinically significant. We report a case of hemolytic disease of the fetus and newborn along with prolonged anemia in newborn twins that persisted for up to 70 days postbirth. The aim was to diagnose and successfully manage hemolytic disease of newborn (HDN) due to maternal alloimmunization. Direct antiglobulin test (DAT), antigen typing, irregular antibody screening and identification were done by polyspecific antihuman globulin cards and standard tube method. At presentation, the newborn twins (T1, T2) had HDN with resultant low reticulocyte count and prolonged anemia, which continued for up to 70 days of life. Blood group of the twins and the mother was O RhD positive. DAT of the both newborns at birth was negative. Anti-M was detected in mothers as well as newborns. Type of antibody in mother was IgG and IgM type whereas in twins it was IgG type only. M antigen negative blood was transfused thrice to twin-1 and twice to twin-2. Recurring reduction of the hematocrit along with low reticulocyte count and normal other cell line indicated a pure red cell aplastic state. Anti-M is capable of causing HDN as well as prolonged anemia (red cell aplasia) due to its ability to destroy the erythroid precursor cells. Newborns with anemia should be evaluated for all the possible causes to establish a diagnosis and its efficient management. Mother should be closely monitored for future pregnancies as well.

Autoimmune Hemolytic Anemia In Cancer Patients At a Tertiary Center In Southern Nigeria

Background With the emergence of non-communicable diseases accounting for 63% of deaths globally in 2008, and about four-fifths of these deaths occurring in the low and middle income countries; Cancer has been identified as the second leading cause of death by the World Health Organization. Anemia is one of the commonest symptoms of cancer and very frequently causes the patient to seek for medical attention even before the cancer is diagnosed. Anemia contributes tremendously to the co-morbidity of cancer, and proper treatment of anemia improves quality of life. Autoimmune haemolytic anemia (AIHA) is a heterogeneous group of diseases characterized by autoantibody production against red cell antigens, leading to their shortened survival. Autoimmunity and cancer are conditions associated with impaired cellular regulation. Immune dysregulation is believed to play a pathogenic role in the development of both autoimmunity and neoplasia. The objectives of this study are to provide baseline data on the prevalence of anemia in cancer in the Niger-Delta region of Nigeria, to determine if AIHA plays a significant role in anemia of cancer, and ascertain the cancers in which AIHA occurs in our environment. Methods This was a case-control study conducted on patients with confirmed diagnoses of solid, soft-tissue and haematological malignancies. Controls were healthy age, sex matched subjects. Cases with, and without exposure to chemotherapy were analyzed as sub groups. Three hundred and seventy six (376) participants (188 cancer patients and 188 controls) were enrolled into the study. Complete blood count, reticulocyte count, peripheral blood film, direct antiglobulin test (DAT), indirect antiglobulin test (IAT) and bilirubin assays were done. The DAT was performed on fresh samples not more than 6 hours after collection using polyspecific antihuman globulin. Analysis was done using Microsoft Office Excel 2007® Results Anemia was found in 124 (66%) of the total cancer population, while only 5 (2.7%) participants had anemia in the control group. Anemia was found in 98 of 149 (65.8%) in the cancer group not yet exposed to chemotherapy, while 26 of 39 cases (66.7%) in the cancer group who had received chemotherapy had anemia. Three (1.6%) of the 188 cancer patients (all not exposed to chemotherapy) were found to have a positive DAT, of which two were strongly positive with features of hemolysis and therefore had AIHA. The 2 patients with AIHA had chronic lymphocytic leukaemia. The third case of positive DAT had malignant teratoma and a weak DAT with no features of hemolysis. The 3 cases of positive DAT had positive IAT. AIHA was the aetiology of the anemia in 2 (2%) of the 98 cases with anemia in the group not yet exposed to chemotherapy. The group receiving chemotherapy had no positive DAT. There was no positive DAT in the control group, however there is no significant difference in the occurrence of AIHA in the cancer group from the controls (p= 0.08) Conclusion The data generated shows that anemia is common in patients with cancer as generally reported. The prevalence of anemia in the cancer group not yet exposed to chemotherapy and those on chemotherapy was about the same. Our data also suggests AIHA may play a role in the aetiology of anemia of cancer; however, patients with lymphoid malignancies are more predisposed. Our results show that a positive DAT may occur without hemolysis. Disclosures: No relevant conflicts of interest to declare.

Flank Pain and Profound Anemia in an 80-Year-Old Female: Table 1

Patient: 80-year-old Caucasian female Chief Complaint: Fatigue, flank pain, and hematuria History of Present Illness: The patient was admitted to the regional hospital after transfer orders from her primary care physician (PCP) subsequent to results of a CBC and a several week history of fatigue and hematuria. The PCP gave her ciprofloxacin to treat the presumed urinary tract infection (UTI). Upon a 1-month follow-up, the patient’s symptoms had not resolved, and the PCP discontinued the ciprofloxacin and started the patient on cephalexin. The patient again presented to her PCP, prior to this admission, with flank pain, in addition to the previous symptoms. Performance of a CBC revealed a hemoglobin level of 4.6 g/dL, and the patient was subsequently transferred to the hospital for treatment of profound anemia. Past Medical and Surgical History: Hypothyroidism Family History: Multiple myeloma Social History: Tobacco use (quit 15 years ago) Physical Examination Vital Signs: Temperature: 36.2°C; pulse 82 beats per minute; respiratory rate, 20 breaths per minute; blood pressure, 133/65. Principal Laboratory Findings: Table 1 Additional Testing: Reference Lab Pre-transfusion Workup Cell Studies: Direct antiglobulin test (DAT) positive to polyspecific anti-human globulin (AHG), anti-immunoglobulin G (IgG), and anti-complement; elution studies were not performed at the time. Serum/Plasma Studies: Autoantibody Reactivity: positive Adsorption Studies: Alloadsorption performed: no alloantibodies to common antigens detected Recommendations: Group O; Rh (D) compatible; least serologically incompatible; cross-matched red cells. Consideration should be given to the use of a properly monitored blood warmer; keep all fluids warm; keep patient warm. 1. What are the patient’s most striking clinical and laboratory findings? 2. What is the differential diagnosis for a patient with these findings? 3. What is the patient’s most likely diagnosis? 4. What protocol needs to take place to differentiate among the different types of autoimmune hemolytic anemias (AIHA)? 5. What is the recommended treatment and management …

Hemolytic anemia after kidney transplantation: a prospective analysis

Hemolysis may occur in 9% to 40% of patients after solid organ transplantation and be caused by the passenger lymphocyte syndrome (PLS). We have prospectively examined 217 kidney transplant recipients before (Day -1) and after (up to Days +10, +20, and +30) surgery. ABO-identical transplant was performed in 180 (82.9%) patients, while 37 (17.1%) individuals received ABO-compatible nonidentical grafts. Direct antiglobulin tests (DATs) were performed by tube technique (polyspecific anti-human globulin [IgG + C3d]), positive DAT samples were further tested by gel agglutination (monospecific anti-IgG, -IgM, -IgA, or -C3), and eluates were prepared from DAT-positive red blood cells (RBCs) by the dichloromethane elution test. We observed that 34 of 217 (15.7%) patients developed a positive DAT up to Day +30. The percentage of patients with positive DATs was significantly higher in those having ABO-compatible nonidentical transplants compared to those that received ABO-identical grafts (10/37 = 27.0% vs. 24/180 = 13.3%; p = 0.037). Specific RBC antibodies (anti-A or anti-B) were found in only 5 of 37 (13.5%) patients having ABO-compatible nonidentical transplants who presented with clinical hemolysis. We found only three reactive eluates from 24 patients with positive DATs who received ABO-identical transplants but had no hemolysis. Our data collected prospectively demonstrated that: 1) positive DATs occurred in 15.7% of all patients up to Day +30 after a kidney transplant; 2) the DAT positivity occurred up to Day +10 in 9.7% of all transplanted patients; 3) the majority of the transplant recipients with a positive DAT had a nonreactive RBC eluate; and 4) PLS was the cause of a positive DAT in 13.5% of patients submitted to ABO-compatible nonidentical kidney transplants.

Antibody elutions in Thai patients with a positive direct antiglobulin test.

The direct antiglobulin test is performed to determine whether an anaemic patient with evidence of haemolysis has autoimmune or alloimmune haemolytic anaemia. We determined the antibody specificity of eluted IgG antibodies from patients' blood samples with a positive direct antiglobulin test. Overall, 134 Thai patients were included in this study. EDTA blood samples were obtained from recently transfused patients, patients with unexplained anaemia and patients who had serum antibodies detected during routine pre-transfusion tests from different hospital blood banks. These complicated samples were sent to the National Blood Centre of the Thai Red Cross Society for investigation and to find compatible blood components. Each blood sample underwent a direct antiglobulin test with the gel technique using polyspecific antihuman globulin and mononospecific anti-IgG and anti-C3d. Acid eluates were prepared from the samples for which the direct antiglobulin test was positive and the specificities of the eluted antibodies were determined by the gel technique. Of the samples tested, 101 showed a positive direct antiglobulin test result (75.4%) using polyspecific antihuman globulin sera whereas only 95 samples (70.9%) were positive with anti-IgG or anti-IgG and anti-C3d. Moreover, 54 of 95 eluates (56.8%) were positive for antibody screening and tested with the reagent panel cells. Twenty-one eluates had specific alloantibodies, which were concordant with the findings in the patients' sera and all patients had a history of blood transfusion. Additionally, 33 eluates contained pan-agglutinins. Interestingly, alloantibodies could be determined using titration studies in 5 of 26 eluates with pan-agglutinins. Although the direct antiglobulin test is not routinely performed in pre-transfusion screening, this test and elution studies would be useful in patients with a history of previous transfusions, and in those for whom compatible blood cannot be found.

International Reference Reagents: Antihuman Globulin

AbstractAn international working party has conducted a study designed to select a suitable reference reagent for antihuman globulin, to replace those first made available in 1987. The chosen preparation contains levels of anti‐lgG and anti‐C3 (anti‐C3c and anti‐C3d) potency that are considered suitable to serve for reference when evaluating either polyspecific antihuman globulin reagents or those containing their separate monospecific components. The reference material is available in 2‐ml freezedried aliquots from seven assigned distribution centres.

Laboratory medicine parameter. Utilizing monospecific antihuman globulin to test blood-group compatibility.

When using polyspecific antihuman globulin (AHG) reagents to detect unexpected antibodies or for crossmatching, reactivity in the AHG phase may be due exclusively to the AHG anticomplement component. A lengthy evaluation may be needed to prove that the reactivity is caused by a "nuisance" antibody, one that is clinically insignificant. Clinically significant transfusion intolerance is rare when caused by blood group alloantibodies, which are detected only with AHG sera that contain anticomplement activity. Using monospecific anti-IgG AHG reagents to detect unexpected antibodies offers reliability while avoiding interference from some common and clinically insignificant IgM complement-fixing antibodies, and thereby saves time and expense.

1 Monoclonal antibodies as blood grouping reagents

The large volume requirements for high quality ABO and Rh(D) typing reagents can now be supplied by selected monoclonal antibodies. Superior anti-A and anti-B monoclonal reagents can be prepared, from blends of at least two antibodies, to optimize the intensity of agglutination for slide tests and the potency for the detection of the weaker sub-groups, including Ax and Bw, by tube techniques. New quality control steps have been described for some highly sensitive anti-A/anti-B antibodies to avoid the detection of traces of A on B cells or traces of B on A1 cells, which results from the non-specific activity of A and B transferases. Excellent anti-A,B reagents may also be made by blends of at least two antibodies to optimize both A and B reactions, but the need for their continued use is now debatable. The development of high titre IgM monoclonal anti-D reagents offers simple rapid saline Rh(D) typing of both patients and donors, but they cannot reliably detect weak D (Du) and some D variants, e.g. the epitopes on D category VI cells. However, this can be achieved by blending an IgM anti-D with IgG (polyclonal) anti-D which can detect these types after conversion of negative saline tests to an antiglobulin phase. In addition, high grade Du, D categories and variants can be reliably detected (for typing donors) by selected monoclonal IgM and IgG anti-Ds by use of suitably enhanced tests without the use of an antiglobulin test.(ABSTRACT TRUNCATED AT 250 WORDS)

Methyldopa-induced hemolytic anemia in a 15 year old presenting as near-syncope

Methyldopa is an antihypertensive medication which is available generically and under the trade name Aldomet that is widely prescribed in the adult population and infrequently used in children. Methyldopa causes an autoimmune hemolytic anemia in a small percentage of patients who take the drug. We report a case of methyldopa-induced hemolytic anemia in a 15-year-old boy who presented to the emergency department with near-syncope. The boy had been treated with intravenous methyldopa during a trauma admission seven weeks prior to presentation. Evaluation revealed a hemoglobin of three grams, 3+ Coombs' test with polyspecific anti-human globulin and monospecific IgG reagents, and a warm reacting autoantibody. Transfusion and corticosteroid therapy resulted in a complete recovery of the patient. Emergency physicians treating children must be aware of this syndrome in order to diagnose and treat it correctly. A brief review of autoimmune and drug-induced hemolytic anemias is provided.

Monoclonal antibodies in blood group serology

The state of the art of monoclonal antibody specifications and blending characteristics needed to produce high quality reagents are described for ABO, RhD and polyspecific anti-human globulin (AHG) reagents. Some interesting advances have been made. Thus some murine monoclonal anti-As (e.g. MH04) see Ax. Also, they may show feeble reactions with the traces of A on some group B cells (the B(A) phenomenon) and the quality control of these reagents is discussed. The use of anti-A,B reagents is now debatable as monoclonal anti-A/anti-B reagents are now more reliable than conventional reagents for detecting weak sub-groups of A and B. RhD typing by saline routine and rapid tests can now be performed with IgM monoclonal anti-D reagents (e.g. MAD-2), but the old problem of Du and D variants is discussed as IgM anti-D is not reliable for their detection. Monoclonal anti-C3c/C3d or just selected anti-C3d (BRIC-8) blended with rabbit anti-IgG make excellent potent clean AHG reagents. The essential false positive test of fresh serum incubated with CPD-A1 red cells from donor pack segment lines is essential for the adjustment and evaluation of AHG reagents. Selected monoclonal anti-M, anti-N, anti-Le a and Le b are established as excellent typing reagents and monoclonal antibodies have now been developed to e, E, K, k and other red cell antigens.

Bias From Commercial Reagent Labels in Laboratory Testing

While the causes of bias in research and clinical trials are of major concern to medical investigators, the sources of bias in established procedures and tests in the clinical laboratory have received less attention. This study demonstrates the extent of prejudice that can occur in the interpretation of test results using two manufacturers' polyspecific anti-human globulin sera. Both brands of reagents were found to be comparable by parallel doubleblind evaluation prior to this trial. Only the label identification of the commercial source was changed. A comparable period of routine testing without label changes was used as control. Personal brand preference caused differences of interpretation and judgment in both the control and trial groups.