The efficacy of performing red cell elution studies in the pretransfusion testing of patients with positive direct antiglobulin tests

In order to evaluate the efficacy of performing red cell elutions in pretransfusion testing, the serologic records of 638 patients with positive direct antiglobulin tests (DAT) were reviewed. These patients were identified by routine antibody screening procedures that included an autologous control. DAT results on the red cells of these patients showed 279 with IgG and C3d sensitization, 319 with IgG alone, and 40 with C3d sensitization alone. Of 638 patients' red cell eluates, 401 demonstrated no reactivity, 154 demonstrated panagglutination, and 60 demonstrated passively acquired anti-A,B. Only 23 of 638 patients had alloantibody sensitization of their red cells. Of the 23, 19 had serum antibody corresponding to the specificity of antibody detected in the eluate. Thus, only four of 638 (0.6%) eluates gave results unavailable by serum testing alone. This study indicates that routine eluate investigation provides little useful information in assuring compatibility. Serum antibody testing and careful review of the clinical and transfusion history constitute appropriate pretransfusion testing in patients with positive direct antiglobulin tests. Eluate testing should be restricted to cases in which immune hemolysis is suspected clinically.     

Hemolytic anemia after kidney transplantation: a prospective analysis

BACKGROUND: Hemolysis may occur in 9% to 40% of patients after solid organ transplantation and be caused by the passenger lymphocyte syndrome (PLS). STUDY DESIGN AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.     

The role of the elution in antibody investigations

BACKGROUND: The direct antiglobulin test (DAT) commonly detects immunoglobulin G (IgG) molecules or complement fragments on the red blood cell (RBC) surface. If IgG antibodies are present then elution procedures can be performed to identify the specificity of these antibodies. Our reference laboratory performs elutions on the RBCs of those patients who have received cellular blood products in the past 30 days and have either a newly identified positive DAT with anti-IgG or the agglutination strength is increased over a previous DAT and if ordered by a clinician regardless of transfusion history. This study questioned how frequently elutions contributed novel serologic information under our reference laboratory's current policy or whether elutions should be performed in more selective serologic conditions.
STUDY DESIGN AND METHODS: Recipients whose RBCs underwent eluate testing were identified from the blood bank's database and information about the antecedent DAT and antibody detection test and eluate was recorded.
RESULTS: In total 648 eluates were evaluated and 82 of 648 (12.7%) revealed a novel antibody not present in the serum (an informative eluate). In 2 of 82 informative eluates non–anti-A/B alloantibodies that were not present in the serum were detected: one example each of anti-D and anti-E. Both were associated with a microscopically positive antecedent DAT. The rate of an informative eluate was higher when the antibody detection test was negative.
CONCLUSION: The strength of the DAT does not indicate the likelihood of an informative eluate. Performing an eluate when the antibody detection test is positive has limited value.     

Positive direct antiglobulin tests at birth without demonstrable maternal antibody

A healthy 38-year-old white woman had two abortions and three live children. Red cells from each of her living children at birth had a strongly positive direct antiglobulin test. Detailed studies on the third child showed that the cells were sensitized by IgG. Maternal serum, tested by a range of techniques against reagent red cells and the husband's cells, showed no unusual antibody. Maternal serum and eluates prepared from red cells of the third child did not react with fresh cells from the older siblings (aged 7 and 10 years). Follow-up on the third child showed that the direct antiglobulin test was positive at 2 months, weakly positive at 4 months, and negative at 8 months. Red cells collected at 8 months of age did not react with the stored eluate prepared from the baby's sensitized red cells at birth. The most likely explanation of these data is that the children inherited a paternal antigen that is only present as a red cell surface-active structure during fetal development.     

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.     

Positive antiglobulin tests due to intravenous immunoglobulin in patients who received bone marrow transplant

To investigate an increased frequency of positive direct (DAT) and indirect (IAT) antiglobulin tests in bone marrow transplant (BMT) patients who received intravenous immunoglobulin (IVIG), serologic testing was performed weekly on blood samples from 94 consecutive BMT patients. Group 1 (47 patients) did not receive IVIG. Group II (47 patients) received high-dose IVIG as prophylaxis for cytomegalovirus infections. Before transplantation no alloantibodies were found in the serums of 92 patients and anti-E was found in the serums of two patients. DATs were negative in all patients before BMT. Four percent of Group I had a positive IAT and 13 percent had a positive DAT. In contrast, 25.5 percent of Group II patients had a positive IAT and 49 percent had a positive DAT, usually within 1 week after initiation of IVIG therapy (p less than 0.001). Antibodies identified in serums and eluates of patients in Group I were anti-A and anti-B. Antibodies identified in serums and eluates of patients in Group II were anti-A, -B, -D, and -K. Twenty-one lots of IVIG were tested and antibodies identified were anti-A, -B, -D, and -K. The data suggest that the higher frequency of positive serologic tests in Group II was due to passively acquired antibodies from high-dose IVIG.     

The evaluation of a positive direct antiglobulin test in pretransfusion testing

The results of serologic studies on 879 blood samples with a positive direct antiglobulin test (DAT) are presented. All blood samples were from patients who were either anemic, for reasons other than blood loss, recently transfused, or had serum antibodies detected during routine pretransfusion tests. Blood samples from only 81 of the patients included in this study had serologically reactive eluates (64 autoantibodies, three antibodies to penicillin and cephalothin treated red blood cells, three passively acquired anti-A antibodies, and 11 transfusion-induced alloantibodies). The eluted antibodies were also detected in the serum by routine pretransfusion tests in 13 of the patients whose red blood cells eluted autoantibodies, and in five of the patients whose red blood cells eluted transfusion-induced alloantibodies. All but one of the 11 transfusion-induced alloantibodies were detected within 14 days posttransfusion. Based on these findings, a cost-effective and safe approach to the management of blood samples with a positive DAT would be to restrict the preparation and testing of eluates to those samples from recently transfused patients. It is the contention of the authors that the incorporation of the DAT in pretransfusion testing should primarily serve to detect alloantibody formation before such antibodies are evident in the serum, and should not be used to screen patients for unsuspected autoimmune hemolytic anemia. Furthermore, the authors question the necessity for blood banks to routinely perform an autocontrol on all blood samples from prospective transfusion recipients.     

The evaluation of a positive direct antiglobulin test (autocontrol) in pretransfusion testing revisited

Direct antiglobulin tests (DATs) using anti-IgG were performed on 65,049 blood samples from prospective transfusion recipients; 3570 tests (5.49%) were positive. Using criteria published previously (primarily excluding patients not transfused within the preceding 14 days), 778 samples from other than neonatal patients were selected for further evaluation. Eluates that did not react were obtained on 518 (66.6%) of these samples. Warm-reactive autoantibodies were apparent in 192 eluates, while 16 contained drug-related antibodies, anti-A or anti-B from prior transfusion with ABO mismatched blood components, or anti-D passively acquired from immune serum globulin. Fifty-two eluates contained alloantibodies; however, in only six of these cases did the corresponding serum lack unexpected alloantibodies, as determined by routine pretransfusion studies. Three additional weakly reactive clinically significant alloantibodies were detected solely through additional serum tests performed on DAT-positive samples. On the basis of these findings, the DAT had a low predictive value when used to detect the early manifestations of an immune response to recently transfused red cells. Elimination of the autocontrol from routine pretransfusion testing, therefore, carries minimal risk to patients yet will undoubtedly contribute to the containment of health care costs. Moreover, the risk is lower than that associated with the elimination of the antiglobulin crossmatch.     

Hemolytic anemia associated with injection of fluorescein

A 49-year-old woman presented with a hemoglobin level of 9.5 g per dL (95 g/L), reticulocyte count of 6.7 percent (0.067), and hemoglobinuria. The next day, the hemoglobin had dropped to 5.8 g per dL (58 g/L), and total bilirubin was 8.8 mg per dL (150 mumol/L). The serum reacted 2+ with all red cells (RBCs). The direct antiglobulin test (DAT) was 3+ with anti-IgG and 1+ with anti-C3, but eluates prepared by two different methods did not react with untreated RBCs. The eluate reacted 2+ with amoxicillin-coated RBCs; amoxicillin had been listed in the patient's record as a previous medication. The patient denied recent ingestion of amoxicillin. Further investigation documented the injection of a dye, fluorescein sodium (AK-FLUOR-25%), for a ophthalmologic fluorescein angiographic study 2 days before admission. RBCs coated with AK-FLUOR reacted with the eluate. Controls consisting of normal serum, an eluate prepared from DAT-negative RBCs, and a serum known to contain anti-penicillin did not react with AK- FLUOR-coated RBCs. Nine days later, the DAT was negative and the serum did not react with untreated RBCs. In the presence of AK-FLUOR (1-in- 125) or amoxicillin (1 mg/mL), the serum reacted 2+ in the antiglobulin test. Antibodies to AK-FLUOR and amoxicillin appeared to react by two mechanisms, which is similar to results in recent reports of other drugs associated with hemolytic anemia. AK-FLUOR has not previously been reported to be associated with hemolytic anemia.     

Incidence of antibody formation and positive direct antiglobulin tests in a multitransfused hemodialysis population

In order to determine the degree and significance of red cell antibody production by dialysis patients, two groups of patients were studied retrospectively. One hundred and five randomly selected dialysis patients (Group I) receiving a total of 1074 units of blood were reviewed, as were 38 patients who were given frozen-thawed red cells because of intractable nonhemolytic febrile reactions following transfusions of red cells stored conventionally (Group II). Eleven patients in Group I produced alloantibodies: nine after the start of dialysis. Of these, two patients had antibodies that were judged clinically insignificant. Eleven of 38 patients in Group II had red cell alloantibodies at the time of study, four of which were judged clinically significant. The direct antiglobulin test (DAT) was positive in 14 patients in Group I and eight patients in Group II for an overall percentage of 15. The cause of the positive DAT was determined in eluates for 26 percent of the cases studied. Clinically significant antibodies were produced by 6.7 percent of randomly selected dialysis patients (Group I). This incidence is lower than other chronically transfused patient populations reported, but higher than that reported in transfused patients at large. The incidence of positive DATs was higher than in some populations reported but not others.     

Evaluation of the manual hexadimethrine bromide (Polybrene) technique in the investigation of autoimmune hemolytic anemia

The use of the direct manual hexadimethrine bromide (Polybrene) test (DPT) in the investigation of patients for autoimmune hemolytic anemia (AIHA) was evaluated. Seventy-nine blood samples from 68 patients were tested. A direct antiglobulin test (DAT) using monospecific reagents and the DPT were performed, and a concentrated ether eluate was tested. The DAT was positive in 62 (78%) of 79 patients and negative in 17 (22%). There is a good correlation among DAT, eluate, and DPT in demonstrating the presence of immunoglobulin on the red cell surface. In contrast, the DPT does not detect C3d and is often negative in cases of AIHA in which C3d alone is demonstrated by the DAT. In DAT-negative cases, DPT results correlated with reactive eluates. However, in four cases of steroid-responsive, DAT-negative hemolytic anemia, the DPT supported the diagnosis of AIHA when the eluate did not react. The DPT is a useful additional screening test for the investigation of AIHA, but it is not recommended as a replacement for either eluate testing or the DAT.     

Life-threatening, antiglobulin test-negative, acute autoimmune hemolytic anemia due to a non-complement-activating IgG1 kappa cold antibody with Pra specificity

A 21-year-old man with fulminant cold autoantibody hemolytic anemia (CAHA) was hospitalized with hemoglobinemia, hemoglobinuria, hemoglobin concentration of 3.3 gm per dL, a negative direct antiglobulin test (DAT) with polyspecific and anti-C3d reagents, a negative Donath-Landsteiner test, and a cold agglutinin titer of 80. He failed to respond to corticosteroids, multiple plasma exchanges, and cyclophosphamide; he required 54 transfusions in 10 days to maintain a hemoglobin concentration of 6.0 to 10.0 g per dL. He improved dramatically after a splenectomy was performed. The wide-thermal-amplitude cold agglutinin proved to be an IgG1 kappa antibody with Pra specificity. The patient's serum exhibited normal complement activation. When the DAT was carried out at 0 to 4 degrees C, the result was strongly positive for IgG; the indirect antiglobulin test at 0 to 4 degrees C was positive with the patient's serum diluted 1 in 640. Within 6 months, he was in complete remission and receiving no therapy. As compared with eight patients with CAHA that was exclusively IgG-mediated, this patient is remarkable for his requirement for many transfusions and for DATs that were consistently negative for C3d.     

Serologic findings in autoimmune hemolytic anemia associated with immunoglobulin M warm autoantibodies

BACKGROUND: Autoimmune hemolytic anemia (AIHA) associated with immunoglobulin M (IgM) warm autoantibodies is unusual but often severe, with more fatalities than other types of AIHA. Diagnosing this type of AIHA can be difficult because routine serologic data are not always informative.
STUDY DESIGN AND METHODS: Forty-nine cases of IgM warm AIHA in 25 years were studied by serologic methods.
RESULTS: Routine direct antiglobulin tests (DATs) detected red blood cell (RBC)-bound C3 in 90 percent of cases (65% had C3 but no immunoglobulin G [IgG] on their RBCs) and IgG in 24 percent. IgM was detected on 29 of 47 (62%) patients' RBCs; RBC-bound IgM was detected in 14 of 47 cases by a tube DAT method and in an additional 15 of 21 (71%) cases using fluorescein isothiocyanate anti-IgM and flow cytometry. Eighty-one percent of eluates from patients' RBCs reacted. Warm autoagglutinins were present in 94 percent of serum samples; untreated and enzyme-treated RBCs were hemolyzed at 37°C by 13 and 65 percent of serum samples, respectively. Most agglutinins were optimally reactive at 30 to 37°C. Patients' RBCs were spontaneously agglutinated in 78 percent of cases; washing with 37°C saline or treating RBCs with dithiothreitol resolved this problem. Clear specificity of autoantibody was defined in 35 percent of serum samples.
CONCLUSION: IgM warm AIHA can be confused with cold agglutinin syndrome and "mixed/combined"-type AIHA; a serologic workup by a specialist reference laboratory can help with the diagnosis.     

凝胶微柱法与试管法检测放散液中抗体的比较

目的比较凝胶微柱法和试管法检测红细胞释放液抗体的能力。方法将30例外周血和41例脐血红细胞用两种方法测定直接抗人球蛋白试验(DAT)并进行酸放散,将放散液与三种谱细胞、A1、B细胞反应检测抗体的特异性。71例中12例作为阴性对照样本(DAT均为阴性),其中6例为健康献血者外周血,6例为不发生新生儿溶血病(Heamolytic disease of thenewborn,HDN)的婴儿脐血样本。结果24例外周血放散液中有10例两种方法均阳性,12例均为阴性,2例自身免疫性溶血性贫血(AIHA)患者样本凝胶微柱法阳性而试管凝集法阴性,6例健康捐献者的样本DAT试验阴性且两种方法检测放散液均为阴性;41例脐血样本中33例放散液两种方法均反应,2例放散液在试管法中与A1和B细胞反应而同样的放散液做凝胶微柱法时一个和A1细胞反应,另一个只与B细胞反应。结论两种方法检测放散液结果基本是一致的,检测AIHA患者红细胞释放液抗体时用微柱法比较好,检测脐血细胞释放的同种血凝素时试管凝集法更好—些。     

Resolution of red cell compatibility testing problems in patients receiving anti-lymphoblast or anti-thymocyte globulin

Passively acquired hemagglutinating antibodies may be detected in the serum of patients receiving horse anti-lymphoblast globulin (ALG) or anti-thymocyte globulin (ATG). Thirty-seven patients receiving ALG following renal transplantation were studied. Eight patients monitored daily all developed positive direct antiglobulin tests (DAT) and positive red cell antibody screening tests. Fifteen of 32 recipients developed red cell antibodies reactive at room temperature in saline, 4 of 32 in albumin at 37 degrees C, and 33 of 37 in the antiglobulin test. Horse globulin was detected on the red cells of all six recipients tested with rabbit anti-horse globulin. Ether eluates prepared from the red cells of 20 patients showed no specificity for common red cell antigens. Anti-human globulin (AHG), absorbed with ALG- coated red cells to remove the component in the AHG which was crossreacting with horse globulin, was used successfully for antibody screening and identification, direct antiglobulin testing, and/or the antiglobulin crossmatching of 27 ALG and ATG recipients, including five with red cell alloantibodies.     

Red cell and platelet-bound IgG penicillin antibodies in a patient with thrombocytopenia

A patient was found to have a positive direct antiglobulin test and thrombocytopenia while on a moderate dose of intravenous penicillin. Serological evaluation of the patient's red cells demonstrated that the positive antiglobulin test was due to antipenicillin antibody. This antibody also was demonstrated in the patient's serum. The patient's platelets had increased quantities of IgG; an eluate from her platelets gave positive test results with platelets treated with penicillin but not normal platelets. Her serum also reacted only with penicillin- treated platelets. Multiple absorptions of her serum with red cells treated with penicillin reduced reactivity against both fresh red cells and platelets treated with penicillin. This patient demonstrated the coexistence of drug-induced immune phenomena directed against both red cells and platelets.     

The detection of cell-bound antibody on complement-coated human red cells

This study sought to elucidate the mechanism by which human red cells, in a variety of clinical settings, become coated in vivo with autologous complement components in the absence of anti-red cell autoantibodies demonstrable by standard methods. By means of a newly developed complement-fixing antibody consumption test, previously undetectable red cell-bound gammaG globulin could be detected and quantified. By this technique, the complement-coated red cells of 13 of 16 patients were shown to carry abnormally high numbers of gammaG molecules per cell, which were nevertheless below the level for detection by the direct antiglobulin test. Eluates were made from the red cells of seven of these patients and each eluate, when sufficiently concentrated, was capable of sensitizing normal human red cells (with gammaG antibodies) to give a positive indirect antiglobulin test with anti-gammaG serum. In the presence of fresh normal serum, six of the eluates so tested were capable of fixing complement to normal human red cells. The antibodies in the red cell eluates did not exhibit Rh specificity and did not react with nonprimate red cells. When studied by sucrose gradient ultracentrifugation, the gammaG antibodies to human red cells in these eluates sedimented in the 7S region. It is concluded that in many patients in whom direct antiglobulin tests reveal only cell-bound complement, the complement fixation is mediated in vivo by small quantities of "warm-reacting" erythrocyte autoantibodies of the gammaG class.     

Comparison of DATs using traditional tube agglutination to gel column and affinity column procedures

BACKGROUND: Detection of immunoglobulin or complement bound to RBCs by using the DAT is valuable in the diagnosis of immune-mediated hemolytic anemia. Traditionally, the DAT has been performed by tube agglutination using anti-IgG or anti-C3d. The purpose of this study was to compare the tube agglutination DAT to gel microcolumn, affinity microcolumn, and flow cytometric DATs on RBCs coated in vitro and on patient RBC samples. STUDY DESIGN AND METHODS: RBCs from 84 patients were assessed by tube agglutination DAT, one gel microcolumn DAT, and two affinity microcolumn DATs. One affinity microcolumn assay was unmodified and one was modified by the addition of polyspecific antiglobulin or anti-IgG as a secondary antibody. RBCs from 15 of the 84 patients underwent analysis by flow cytometry with fluorescence-labeled anti-IgG. The assays were also compared by using D+ RBCs sensitized with serially adjusted concentrations of anti-D. RESULTS: Both tube agglutination and gel microcolumn DATs were positive in 49 patient samples; both assays were negative in 20 samples, and the results were discordant in 15. Gel microcolumn DATs were more likely than were tube agglutination DATs to detect IgG on RBCs. Affinity microcolumn DATs were less likely than gel microcolumn or tube agglutination DATs to detect IgG on RBCs. Flow cytometry results were the same as gel microcolumn results in 12 of 15 patient samples and the same as tube agglutination results in 13 of 15. Tube agglutination and both affinity microcolumn assays reacted with RBCs coated with anti-D that was diluted 1-in-100. The gel microcolumn and flow cytometry assays reacted with RBCs coated with anti-D diluted 1-in-400. There was no correlation between tube agglutination and gel microcolumn DATs in detecting bound C3d. CONCLUSION: Detection of IgG bound to RBCs was not consistent with the methods described. Gel microcolumn DATs were more sensitive than tube agglutination and affinity microcolumn DATs. Given the varied results of these assays, reference laboratories should not rely on a single method for DATs. More comprehensive testing should be performed when the tube agglutination DAT is negative in a patient with suspected immune-mediated hemolytic anemia. Further comparisons are necessary to determine the proficiency of flow cytometric assays.     

Clinical application of a flow cytometric direct antiglobulin test

BACKGROUND: The clinical application of flow cytometric direct antiglobulin test (FC-DAT) has rarely been evaluated for patients with various diseases including immune and nonimmune hemolytic anemia.
STUDY DESIGN AND METHODS: Blood samples from 380 patients with a variety of diseases were studied using the tube direct DAT and FC-DAT. The results of tube DAT and FC-DAT were compared. The predictive values of DAT for hemolysis were evaluated.
RESULTS: Of 57 patients with autoimmune hemolytic anemia (AIHA), 6 of the 17 with a negative tube DAT (immunoglobulin G [IgG]) had a positive FC-DAT (IgG) and 23 of the 36 patients with a negative tube DAT (complement 3d [C3d]) had a positive FC-DAT (C3d). In 57 patients with AIHA, the incidence of positive results of FC-DAT (IgG) and tube DAT (IgG) were similar (42 positive vs. 40 positive); but in 323 patients without AIHA, the incidence of positive FC-DATs (IgG) was higher than that of tube DAT (IgG; 47 positive vs. 9 positive). The higher incidence of positive FC-DAT (C3d) than that of tube DAT (C3d) was seen in patients with AIHA (42 positive vs. 21 positive) as well as in patients without AIHA (61 positive vs. 5 positive). Both DAT (IgG) and DAT (C3d) positive has highest positive predictive value for hemolysis, followed by DAT (IgG) alone positive and DAT (C3d) alone positive.
CONCLUSIONS: FC-DAT is a complementary test for diagnosing AIHA. There is a synergistic effect of the red blood cell–bound IgG and complement in predicting hemolysis.     

Clinical significance of serologic markers related to red blood cell autoantibodies production after red blood cell transfusion—severe autoimmune hemolytic anemia occurring after transfusion and alloimmunization: successful treatment with rituximab

BACKGROUND: The association of autoantibody formation with blood transfusion was previously noted. Severe autoimmune hemolytic anemia (AIHA) diagnosed after red blood cell (RBC) transfusion determined us to undertake this study and investigate the incidence and clinical significance of autoantibodies occurring after transfusion by a retrospective review of blood bank and medical records.
STUDY DESIGN AND METHODS: We report a lymphoma patient who developed severe autohemolysis after blood transfusion and alloantibody production. The hemolysis was refractory to steroids and chemotherapy and ceased after rituximab. We also retrospectively assessed the blood bank records for a 2-year period to identify the patients who developed autoantibodies after blood transfusion and examined laboratory, clinical features, and outcome.
RESULTS: From January 2005 through December 2006, 375 direct antiglobulin tests (DATs) and 3409 indirect antiglobulin tests (IATs) were found to be positive. Thirty-eight patients with positive DATs and IATs had demonstrable RBC warm-type autoantibodies occurring after blood transfusion; 27 of them had also one or more alloantibodies. Clinical and laboratory signs of hemolysis were absent in all patients (except the case reported). In another 5 patients alloantibodies were retrieved from RBC eluate and serum without evidence of autoantibodies; therefore, a delayed serologic transfusion reaction was diagnosed.
CONCLUSION: RBC autoantibodies are quite commonly found after blood transfusion. Nevertheless, clinically significant AIHA is a rare but at times a life-threatening phenomenon. We describe a first case of successful treatment with rituximab of refractory posttransfusion AIHA. Rituximab must be further evaluated for this indication.