Warm reactive autoantibodies detected by solid phase technology: Patient characteristics, laboratory features, and clinical significance.

OBJECTIVES: This study focused on the serology, clinical characteristics, and hemolytic potential of warm reactive autoantibodies detected by solid phase red cell adherence. METHODS: Ninety-seven patients with warm autoantibodies were evaluated. Serologic characteristics included the strength of solid phase reactivity, the results of tube-based ancillary testing, direct antiglobulin test and eluate results, and an assessment for contemporaneous alloantibodies. Clinical characteristics of the patients included age, sex, and primary diagnosis. Each patient was also assessed for evidence of hemolysis. RESULTS: Most of the 97 study patients were female (63.9%), and the average age was 66 years. Hematologic disorders were the most common diagnosis. A majority (70.1%) of the warm autoantibodies had 3 to 4+ reaction strengths, and approximately 90% had negative testing with at least 1 test tube method. There was an even distribution of direct antiglobulin test reaction strengths, with 74% reactive with anti-immunoglobulin G only. Alloantibodies were identified in 20% of patients. Evidence of hemolysis was identified in only 13 patients (13.4%). CONCLUSIONS: Warm reactive autoantibodies are more likely to be hemolytic, have strongly reactive indirect and direct antiglobulin tests, remain reactive in tube-based ancillary testing methods, and are seen primarily in patients with hematologic disorders.

Three Rwandan Children With Massive Splenomegaly and Epstein-Barr Virus-associated Lymphoproliferative Disorders: Case Presentations and the Literature Review.

This report describes 3 Rwandan children with massive splenomegaly and pancytopenia who underwent splenectomy. Each was diagnosed with Epstein-Barr virus-associated lymphoproliferative disorder (EBV LPD) based on lymphocyte morphology, lymphocyte immunophenotype, and the results of EBV in situ hybridization studies. The differential diagnosis of splenomegaly, with a special emphasis on the sub-Saharan African context, is discussed along with EBV and associated disorders. These cases serve as a call to consider EBV LPD in the differential diagnosis of splenomegaly in children in whom common causes have been ruled out.

Strict vs lenient criteria for elution testing: comparison of yields between two tertiary care medical centers.

In this study, 2 patient populations, using different elution strategies, were compared to evaluate eluate yields under more and less restrictive conditions. An informative eluate was defined as one in which an antibody that could be clinically significant was detected in the eluate but was not detectable in the plasma at the time of elution testing. The results for 160 direct antiglobulin tests (DATs) and 160 elution studies were evaluated in 71 patients at the adult hospital (lenient criteria). The results for 372 DATs and 43 elution studies were evaluated in 123 patients at the pediatric hospital (strict criteria). The yields from these eluates were 0.6% at the adult hospital (C antibody) vs 2.3% at the pediatric hospital (Jk(a) antibody). Thus, the yield of information from eluate testing is low regardless of the stringency applied to testing. However, considering the cost and time required for testing, more stringent criteria are advised.

Recombinant polymeric IgG anti-Rh: a novel strategy for development of direct agglutinating reagents.

Anti-Rh alloantibodies are used in research and clinic laboratories to define the Rh antigenic profile of human blood samples. IgM anti-Rh antibodies directly agglutinate Rh-positive RBCs. Anti-Rh antibodies of the IgG isotype bind to Rh antigens with a higher intrinsic affinity than IgM and sensitize RBCs, but do not induce direct hemagglutination. The aim of this work was to produce IgG anti-Rh possessing direct hemagglutinating properties of IgM. To achieve this goal, recombinant antibody technology was used to construct genes encoding Ig light and heavy chains that will form polymers with anti-Rh specificity. Expression vectors and liposome-mediated DNA transfer were used to generate transfectomas secreting human recombinant IgG3 anti-Rh. ELISA, SDS-PAGE, and hemagglutination were used to identify and characterize the recombinant antibody produced. Thus, a recombinant polymeric IgM-like IgG3 anti-Rh antibody was produced that directly agglutinates RBCs with specificity identical to that of the parent non-agglutinating IgG. The results obtained suggest that the technology used here to generate polymeric IgM-like IgG3 anti-Rh antibodies can be applied to produce Rh blood typing reagents. This approach might also be used to develop reagents for which cell surface antigen binding and agglutination or aggregation is required.

Hemolytic disease of the fetus and newborn due to anti-Ge3: combined antibody-dependent hemolysis and erythroid precursor cell growth inhibition.

The Gerbich (Ge) antigens are a collection of high-incidence antigens carried on the red blood cell membrane glycoproteins, glycophorins C and D. Antibodies against these antigens are uncommon, and there have been only rare case reports of hemolytic disease of the fetus and newborn due to anti-Ge. In this case report, we present a neonate with severe anemia and hyperbilirubinemia due to anti-Ge3. Routine and special laboratory studies undertaken in this case suggested two mechanisms for the patient's hemolysis and persistent anemia. Antibody-dependent hemolysis was associated with early-onset hyperbilirubinemia, anemia, and a mild reticulocytosis, and inhibition of erythroid progenitor cell growth was associated with late anemia and normal bilirubin and reticulocyte values. Though rare, anti-Ge3 can be a dangerous antibody in pregnancy. Affected neonates may require intensive initial therapy and close follow-up for at least several weeks after delivery.

Warm-reactive autoantibodies in pediatric patients: clinical and serologic correlations.

The significance of warm-reactive autoantibodies in pediatric patients has not been a subject of thorough evaluation. This study was undertaken to correlate the clinical and serologic features of these antibodies to identify predictors of clinical significance. Forty-two consecutive patients with serologically detectable warm-reactive autoantibodies were studied. These patients (21 male, 21 female) had a mean age of 9 years (range: 2 mo to 21 y). Primary diagnoses included autoimmune disorders (14), sickle cell disease (14), viral infection (4), idiopathic autoimmune hemolytic anemia (2), leukemia (2), and other diseases (6). Autoimmune hemolysis, as determined by clinical and laboratory findings, was documented in 24 patients (57%). Serologic studies revealed that all patients demonstrated IgG on their red cells [Direct Antiglobulin Test (DAT) reactivity range: microscopic to 3+]; 17 (40%) also demonstrated complement (DAT reactivity range: microscopic to 2+). There was a correlation between the strength of the DAT for IgG and the presence of complement on the red cells, with both being important predictors of hemolysis. These findings may be useful in predicting the clinical significance of warm-reactive autoantibodies in pediatric patients and allow for more efficient and effective follow-up care.

Severe neonatal hemolysis due to a maternal antibody to the low-frequency Rh antigen C(w).

C(w) is a low-frequency antigen in the Rh blood group system with a prevalence of approximately 2% in whites. Although anti-C(w) is not an uncommon antibody in pregnancy (0.1% incidence), clinically significant hemolytic disease of the newborn is highly unusual. We report the case of an infant with severe hyperbilirubinemia and persistent anemia due to a high-titer maternal C(w) antibody. The medical literature relating to maternal C(w) alloimmunization and neonatal outcome is also reviewed. In addition, recommendations are made regarding the management of pregnancies and newborns complicated by antibodies to C(w).

Transfusion-associated graft-versus-host disease: a serious residual risk of blood transfusion.

Transfusion-associated graft-versus-host disease (TA-GVHD) is well recognized as an uncommon, but frequently fatal, adverse effect of blood component therapy. In this disorder, viable donor lymphocytes transfused to a vulnerable patient orchestrate a devastating attack on the recipient's tissues. In contrast to the striking reduction in infectious risks of blood transfusion, a significant residual risk of TA-GVHD remains. This article reviews the pathogenesis and mechanism of TA-GVHD, which provide the foundation for a prevention strategy. A review of selected recent cases illustrates the challenges faced in the identification, prevention, and treatment of this frustrating disorder.

Warm reactive autoantibodies: clinical and serologic correlations.

Warm reactive autoantibodies are encountered relatively frequently in tertiary care hospitals. We studied 100 consecutive patients with warm autoantibodies to correlate their clinical and serologic features. Study patients (56 male, 44 female) had various diagnoses and a mean age of 53.5 years (range, 3-90 years). Autoimmune hemolysis was documented in 29 patients; 20 patients (69%) in this subset had diseases classically associated with warm autoimmune hemolytic anemia (hematologic and autoimmune disorders). All study patients demonstrated IgG on their RBCs (direct antiglobulin test [DAT] reactivity range, microscopic to 4+); 49 also demonstrated C3 (reactivity range, microscopic to 3+). The DAT for IgG was 2+ or more in 25 (86%) of 29 patients with hemolysis; the DAT for IgG was 1+ or less in 45 (63%) of 71 patients without hemolysis. In patients with hemolysis, 21 (72%) of 29 had a DAT reactive for C3. These findings may be useful in determining the clinical significance of warm autoantibodies and the extent to which patients should be followed up for hemolysis.

Hemolytic uremic syndrome revisited: Shiga toxin, factor H, and fibrin generation.

The hemolytic uremic syndrome (HUS) is a disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, and renal failure. These features reflect the underlying histopathologic lesion: fibrin-rich thrombi that predominate in the renal microvasculature. HUS most commonly affects children younger than 5 years and is associated with Shiga toxin-producing enteric bacteria, the most important of which is Escherichia coli O157:H7. In this setting, HUS is epidemic and also might affect adults, particularly elderly people. Sporadic cases of HUS more commonly occur in adults and are associated with a wide variety of inciting agents and conditions. Although the disease manifestations might be similar and endothelial activation or injury likely represents a common etiologic event, differing responses to therapy suggest different pathogenic mechanisms. As more is understood about the underlying pathogenesis of the diseases that we now lump together as HUS, more efficacious and rational treatment and prevention strategies are likely to follow.

Thrombotic thrombocytopenic purpura: from platelet aggregates to plasma.

Thrombotic thrombocytopenic purpura (TTP) is a syndrome of severe thrombocytopenia and microangiopathic hemolytic anemia without an alternative explanation. Although some patients also have a combination of fever and neurologic and/or renal manifestations, these are not required for the diagnosis. Thus, plasmapheresis should start as soon as TTP is placed high in the differential diagnosis to prevent significant mortality. Histopathologically, TTP is characterized by widespread platelet thrombi in the microcirculation. Ultralarge von Willebrand factor (vWf) multimers found in the patient's plasma are the basis for the platelet thrombi. Recent evidence has linked the abnormal fragments of vWf with deficiency of a plasma enzyme named vWf-cleaving protease, or ADAMTS-13. While a small percentage of patients with TTP have a constitutional defect in this enzyme, many with the acute idiopathic form have an antibody to ADAMTS-13, affecting its ability to cleave vWf. The determination of the enzyme activity and the presence of its inhibitor have emerged as a potential tool in the diagnosis and prognosis of TTP. Furthermore, it helps to differentiate TTP from the hemolytic uremic syndrome, in which the level of ADAMTS-13 is expected to be normal or only slightly decreased.

Clinical significance of anti-Jra: report of two cases and review of the literature.

BACKGROUND: Jra is a high-frequency antigen seen in all populations, but the clinical significance of Jra antibodies is incompletely understood. Two cases are reported in which patients with anti-Jra received incompatible transfusions. CASE REPORTS: A 69-year-old Japanese man had anti-K and anti-Jra. Despite multiple transfusions of Jr(a+), K- RBCs, his clinical course remained stable without evidence of hemolysis. A 45-year-old Japanese woman with anti-Jra was transfused with two units of Jr(a+) RBCs without clinical evidence of hemolysis. However, the same patient received an additional unit of Jr(a+) RBCs 1 week after the initial transfusions and, within 6 hours of transfusion, developed signs and symptoms of an acute hemolytic transfusion reaction. STUDY DESIGN AND METHODS: Routine serologic methods were used to study the patients' RBCs and plasma. A monocyte monolayer assay (MMA) was used to determine the potential clinical significance of the anti-Jra, where reactivity (R) greater than 5 percent indicates potential clinical significance. RESULTS: The anti-Jra in the first case had a pretransfusion titer of 32 with a MMA result of 3.3 percent R. No clinical or laboratory evidence of hemolysis was seen after transfusion of 4 units of Jr(a+), K- RBCs. The anti-Jra in the second case had a pretransfusion titer of 32 with a MMA result of 24.5 percent R. This patient developed an acute hemolytic reaction after transfusion of Jr(a+) RBCs. CONCLUSION: Anti-Jra can be clinically significant as demonstrated by acute hemolysis in the second case. The MMA accurately predicted the clinical outcome of each case and appears to be a useful tool in predicting the biologic behavior of anti-Jra.