Expanding Phenotype of Schimke Immuno-Osseous Dysplasia: Congenital Anomalies of the Kidneys and of the Urinary Tract and Alteration of NK Cells.

Schimke immuno-osseous dysplasia (SIOD) is a rare multisystemic disorder with a variable clinical expressivity caused by biallelic variants in SMARCAL1. A phenotype-genotype correlation has been attempted and variable expressivity of biallelic SMARCAL1 variants may be associated with environmental and genetic disturbances of gene expression. We describe two siblings born from consanguineous parents with a diagnosis of SIOD revealed by whole exome sequencing (WES). Results: A homozygous missense variant in the SMARCAL1 gene (c.1682G>A; p.Arg561His) was identified in both patients. Despite carrying the same variant, the two patients showed substantial renal and immunological phenotypic differences. We describe features not previously associated with SIOD-both patients had congenital anomalies of the kidneys and of the urinary tract and one of them succumbed to a classical type congenital mesoblastic nephroma. We performed an extensive characterization of the immunophenotype showing combined immunodeficiency characterized by a profound lymphopenia, lack of thymic output, defective IL-7Rα expression, and disturbed B plasma cells differentiation and immunoglobulin production in addition to an altered NK-cell phenotype and function. Conclusions: Overall, our results contribute to extending the phenotypic spectrum of features associated with SMARCAL1 mutations and to better characterizing the underlying immunologic disorder with critical implications for therapeutic and management strategies.

Alveolar cells under mechanical stressed niche: critical contributors to pulmonary fibrosis.

Pulmonary fibrosis arises from the repeated epithelial mild injuries and insufficient repair lead to over activation of fibroblasts and excessive deposition of extracellular matrix, which result in a mechanical stretched niche. However, increasing mechanical stress likely exists before the establishment of fibrosis since early micro injuries increase local vascular permeability and prompt cytoskeletal remodeling which alter cellular mechanical forces. It is noteworthy that COVID-19 patients with severe hypoxemia will receive mechanical ventilation as supportive treatment and subsequent pathology studies indicate lung fibrosis pattern. At advanced stages, mechanical stress originates mainly from the stiff matrix since boundaries between stiff and compliant parts of the tissue could generate mechanical stress. Therefore, mechanical stress has a significant role in the whole development process of pulmonary fibrosis. The alveoli are covered by abundant capillaries and function as the main gas exchange unit. Constantly subject to variety of damages, the alveolar epithelium injuries were recently recognized to play a vital role in the onset and development of idiopathic pulmonary fibrosis. In this review, we summarize the literature regarding the effects of mechanical stress on the fundamental cells constituting the alveoli in the process of pulmonary fibrosis, particularly on epithelial cells, capillary endothelial cells, fibroblasts, mast cells, macrophages and stem cells. Finally, we briefly review this issue from a more comprehensive perspective: the metabolic and epigenetic regulation.

Neurological injuries in COVID-19 patients: direct viral invasion or a bystander injury after infection of epithelial/endothelial cells.

A subset of patients with coronavirus 2 disease (COVID-19) experience neurological complications. These complications include loss of sense of taste and smell, stroke, delirium, and neuromuscular signs and symptoms. The etiological agent of COVID-19 is SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), an RNA virus with a glycoprotein-studded viral envelope that uses ACE2 (angiotensin-converting enzyme 2) as a functional receptor for infecting the host cells. Thus, the interaction of the envelope spike proteins with ACE2 on host cells determines the tropism and virulence of SARS-CoV-2. Loss of sense of taste and smell is an initial symptom of COVID-19 because the virus enters the nasal and oral cavities first and the epithelial cells are the receptors for these senses. Stroke in COVID-19 patients is likely a consequence of coagulopathy and injury to cerebral vascular endothelial cells that cause thrombo-embolism and stroke. Delirium and encephalopathy in acute and post COVID-19 patients are likely multifactorial and secondary to hypoxia, metabolic abnormalities, and immunological abnormalities. Thus far, there is no clear evidence that coronaviruses cause inflammatory neuromuscular diseases via direct invasion of peripheral nerves or muscles or via molecular mimicry. It appears that most of neurologic complications in COVID-19 patients are indirect and as a result of a bystander injury to neurons.

Elevated levels of autoantibodies against EXD2 and PHAX in the sera of patients with chronic thromboembolic pulmonary hypertension.

While circulating autoantibodies have been detected in patients with several cardiovascular diseases, such studies have not been performed for chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH). Here we investigated the production of certain auto-antibodies in CTEPH patients. Initial screening was performed in 5 CTEPH patients and 5 healthy donors (HDs) using a ProtoArray Human Protein Microarray v5.1 containing 9,375 human proteins, and we selected 34 antigens recognized by IgG antibodies more strongly in the sera of CTEPH patients than in the sera of HDs. In subsequent second/third analyses, we validated the auto-antibody level using amplified luminescent proximity homogeneous assay-linked immunosorbent assay (AlphaLISA) in 96 CTEPH patients and 96 HDs as follows: At the second screening, we used 63 crude peptides derived from those selected 34 antigens and found that the serum levels of autoantibodies for 4 peptides seemed higher in CTEPH patients than in HDs. In third analysis, we used the purified peptides of those selected in second screening and found that serum antibodies against peptides derived from exonuclease 3'-5' domain-containing 2 (EXD2) and phosphorylated adaptor for RNA export (PHAX) were significantly higher in CTEPH patients than in HDs. The serum antibody levels to these antigens were also elevated in PAH patients. The titers against EXD2 peptide decreased after surgical treatment in CTEPH patients. These autoantibodies may be useful as biomarkers of CTEPH and PAH, and further investigations may provide novel insight into the etiology.

Influence of aspirin on the CX3CL1/CX3CR1 signaling pathway in acute pulmonary embolism.

The present study aimed to explore the influence of aspirin on the CX3CL1/CX3CR1 signaling pathway in acute pulmonary embolism (APE) in rats. Our previous study found that CX3CL1/CX3CR1 was increased in APE. However, the effect of this signaling pathway on APE remains unclear. CX3CL1-shRNA adenovirus and CX3CL1-overexpression vector were constructed. Male Sprague-Dawley rats were randomly divided into 9 groups (n=10): normal group (group N), sham operation group (group Sham), sham operation + aspirin group (group ASP), model group (group M), model + ASP group (group M+A), model + shRNA group (group M+SH), sham operation + CX3CL1-overexpression vector group (group Sham+Cx3), model + ASP + shRNA group (group M+A+SH), and model + ASP + CX3CL1-overexpression vector group (group M+A+CX3). Arterial pressure detection, hematoxylin and eosin staining, reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, and laser confocal scanning microscopy were applied. Aspirin significantly decreased pulmonary artery pressure, improve pathological changes in the embolism, and decreased the expression of CX3CL1/CX3CR1 and CX3CL1/NF-κB. Moreover, the adenovirus-overexpression CX3CL1 vector aggravated the inflammatory changes in APE, which were improved by aspirin. However, the intervention of the adenovirus CX3CL1 vector reduced the change, while its combination with aspirin significantly improved the change. In conclusion, aspirin improved pathological changes in rats with APE via the CX3CL1/CX3CR1 signaling pathway.

[The clinical manifestations and thrombotic risk factors in primary antiphospholipid syndrome].

OBJECTIVE: To investigate the clinical characteristics in patients with primary antiphospholipid syndrome (PAPS) and to identify potential predictors of thrombotic events. METHODS: A total of 107 patients with PAPS were enrolled in our study, who were admitted in Peking Union Medical College Hospital from January 2004 to December 2014. Demographic data, age at onset, disease duration, past history of hypertension and regular cigarette smoking, clinical manifestations, imaging characteristics, management and prognosis were retrospectively collected. Bivariate statistical analysis and logistical regression test were performed to compare the discrepancy between patients with or without thromboembolic events. RESULTS: In 107 patients, there were 65 female and 42 male patients, with mean age (39.8±15.8) years old, median disease duration 10.5 (2.0, 48.0) months. A total of 72(67.3%) patients reported episodes of thromboembolic events, including 72 venous thromboses and 29 arterial thromboses. The most frequent venous thromboses were deep vein thromboses (35.5%), pulmonary embolism the second common (29.9%), with cranial venous sinus thromboses the following (8.4%). In arterial thromboembolic events, the incidence of transient ischemic attack (TIA) and ischemic stoke was the highest(14.0%), embolism of lower extremities the second (6.5%), and 4 patients (3.7%) with acute myocardial infarction. Sixty seven patients(62.6%)had positive lupus anticoagulant, 60 patients(56.1%)with positive anticardiolipin antibody, 32 patients(29.9%, 32/74) with positive ß2 glycoprotein Ⅰ(ß2GPⅠ). Forty patients(37.4%)had double positive antibodies, while 19 cases(17.8%)with triple positive. In logistical regression, aging (per 10 years) and hypocomplementemia were significantly related to venous thrombosis (OR=1.421, 95%CI 1.066-1.894, P<0.05, and OR=6.435, 95%CI 1.374-30.130, P<0.05, respectively). Cigarette smoking and triple positive antibodies were independent risk factors of arterial thrombosis (OR=3.996, 95%CI 1.079-14.795, P<0.05 and OR=3.166, 95%CI 1.102-9.097, P<0.05, respectively). CONCLUSION: APS is an autoimmune disorder characterized by recurrent arterial and venous thromboembolic events. Venous thromboembolism is more common than the arterial. Age and hypocomplementemia are predictors of venous thromboembolism; while smoking and triple positive antibodies are independent risk factors of arterial thromboembolism.

Proteus syndrome: evaluation of the immunological profile.

Proteus syndrome (PS) is an extremely rare and complex disease characterized by malformations and overgrowth of different tissues. Prognosis of affected patients may be complicated by premature death, mostly due to pulmonary embolism and respiratory failure. To date, immunological data in Proteus syndrome are scarse.We report on the novel immunologic findings of a 15 years old girl affected with PS. Detailed T and B cell evaluation revealed maturational alterations for both subsets and functional hyperactivation for the latter. Such findings have not been reported previously in PS and may be the spy of more complex immune abnormalities in this syndrome.

Soluble urokinase plasminogen activator receptor and incidence of venous thromboembolism.

Raised plasma levels of the soluble urokinase plasminogen activator receptor (suPAR) have been associated with increased incidence of cardiovascular diseases. Whether suPAR is associated with venous thromboembolism (VTE) is largely unknown. The purpose of the present study was to investigate the relationship between suPAR and incidence of VTE in a cohort study. suPAR was measured in 5,203 subjects (aged 46-68 years, 58 % women) from the general population, who participated in the Malmö Diet and Cancer (MDC) study between 1991 and 1994. Incident cases of VTE were identified from the Swedish patient register during a mean follow-up of 15.7 years. Of 5,203 subjects with measurements of suPAR, 239 had VTE during follow-up (127 venous thrombosis, 86 lung embolism, 26 both). Incidence of VTE was significantly higher in subjects with suPAR levels in the top quartile. Adjusted for age and sex, the HR (4th vs 1st quartile) was 1.74 (95 %CI: 1.2-2.6, p for trend=0.003). After adjustments for risk factors, the HR was 1.66 (95 %CI: 1.1-2.5, p for trend=0.016). High level of suPAR was a risk indicator for incidence of VTE in this population-based cohort study. The causal relationships between suPAR and VTE remain to be explored.

Extracellular DNA and histones: double-edged swords in immunothrombosis.

The existence of extracellular DNA in human plasma, also known as cell-free DNA (cfDNA), was first described in the 1940s. In recent years, there has been a resurgence of interest in the functional significance of cfDNA, particularly in the context of neutrophil extracellular traps (NETs). cfDNA and histones are key components of NETs that aid in the host response to infection and inflammation. However, cfDNA and histones may also exert harmful effects by triggering coagulation, inflammation, and cell death and by impairing fibrinolysis. In this article, we will review the pathologic nature of cfDNA and histones in macrovascular and microvascular thrombosis, including venous thromboembolism, cancer, sepsis, and trauma. We will also discuss the prognostic value of cfDNA and histones in these disease states. Understanding the molecular and cellular pathways regulated by cfDNA and histones may provide novel insights to prevent pathological thrombus formation and vascular occlusion.

Epidemiology and pathophysiology of venous thromboembolism: similarities with atherothrombosis and the role of inflammation.

Venous thromboembolism (VTE) is a multifactorial disease. Major provoking factors (e. g. surgery, cancer, major trauma, and immobilisation) are identified in 50-60 % of patients, while the remaining cases are classified as unprovoked. However, minor predisposing conditions may be detectable in these patients, possibly concurring to the pathophysiology of the disease, especially when co-existing. In recent years, the role of chronic inflammatory disorders, infectious diseases and traditional cardiovascular risk factors has been extensively investigated. Inflammation, with its underlying prothrombotic state, could be the potential link between these risk factors, as well as the explanation for the reported association between arterial and venous thromboembolic events.

Antiphospholipid syndrome and the heart: a case series and literature review.

Antiphospholipid syndrome is a rare autoimmune disease characterized by a high tendency of developing thrombotic events. It is diagnosed in the presence of specific laboratory criteria (positivity for lupus anticoagulant, and the presence of anticardiolipin and aß2GPI antibodies) and clinical criteria such as thrombosis in any district (arterial or venous) and pregnancy morbidity. Being a multisystem disease, the heart is commonly affected by direct (autoimmune mediated action) or indirect (thrombosis) pathological mechanisms. Heart valve lesions are the most frequent manifestations; however, the haemodynamic significance is quite uncommon but when it occurs it may require surgery that further complicates the picture due to the high risk of thrombosis. Coronary arteries and myocardium are also affected leading to ischaemic heart disease and left ventricular dysfunction. Other findings include chronic thromboembolic pulmonary hypertension and accelerated atherosclerosis. The consequences of heart involvement may be significant in overt disease. The treatment of cardiac complications is challenging and requires an in-depth knowledge of the disease.

Deterioration of thromboses in primary antiphospholipid syndrome: TNF-alpha and anti-annexin A5 antibodies.

BACKGROUND: To investigate the association between clinical and serological features of patients with primary antiphospholipid syndrome (PAPS) and TNF-alpha, interleukin 6 (IL-6), and soluble IL-2 receptor (sIL-2R). METHODS: ELISA was used for measurement of antibodies (Abs) and TNF-alpha, while IL-6 and sIL-2R were measured by chemiluminescence. RESULTS: PAPS patients with pulmonary emboli showed positive correlation between IgM isotype of anti-annexin A5 antibodies and TNF-alpha (r = 0.894, p = 0.041) and IgM class of anticardiolipin antibodies and sIL-2R (r = 0.900, p = 0.037). In PAPS with cerebrovascular insults, positive correlation was noticed between TNF-alpha and IgG isotype of anticardiolipin (r = 0.624, p = 0.040) and anti-annexinA5 Abs (r = 0.768, p = 0.006). CONCLUSIONS: Isotype analysis of antiphospholipid and anti-annexin A5 Abs and investigation of their association with TNF-alpha is important for differentiation of PAPS patients that are prone to further deterioration of arterial and venous thromboses.

Detection of thromboembolism with 99mTc-labeled F(ab)2 fragment of anti-glycoprotein IIIa chimeric monoclonal antibody in beagle canines.

INTRODUCTION: Rapid and timely diagnosis of pulmonary embolism (PE) and deep venous thrombosis (DVT) is important to improve patient outcome. The goal of this study was using (99m)Tc-chSZ21-F(ab)(2), F(ab)(2) fragment of anti-glycoprotein IIIa chimeric monoclonal antibody, to image experimental thromboembolism (DVT and PE) in dogs. MATERIALS AND METHODS: Flow cytometry assay and adenosine diphosphate (ADP) stimulated platelet aggregation was performed to determine the specificity and affinity of chSZ21-F(ab)(2) to the GPIIb/IIIa receptor on human or canine platelets. Both PE and DVT were induced in 12 beagle canines by catheter under X-ray direction. After (99m)Tc-chSZ21-F(ab)(2) injection,animals were imaged for up to 3 hours then heparinized and sacrificed. RESULTS: Specific binding of chSZ21-F (ab)(2) to GPIIb/IIIa on human or canine platelets was verified by flow cytometry assay. chSZ21-F (ab)(2) inhibited ADP induced platelet aggregation with a dose-dependent manner, the concentration required to inhibit 50% (IC(50)) of platelet aggregation was 11.6 ± 7.9 nM and 24.9 ± 18.8 nM for human and canine, respectively. In vivo, focal uptake was observed in planar images as early as 30 min (DVT) and 60 min (PE), and became clearer within 3 hours after injection. Lesion-to-background ratio averaged 12.8 (PE-to-lung), 7.2 (DVT-to-blood), and 117.0(DVT-to-muscle), respectively. CONCLUSIONS: These results suggested that (99m)Tc-chSZ21-F(ab)(2) with high DVT and PE uptake is a promising agent for imaging vascular thrombosis.

Soluble CD40 ligand levels in acute pulmonary embolism: a prospective, randomized, controlled study.

CD40 ligand is a thromboinflammatory molecule that predicts cardiovascular events. Platelets constitute the major source of soluble CD40 ligands (sCD40L), which has been shown to influence platelet activation. The main aim of this study was to evaluate sCD40L levels in patients with acute pulmonary embolism (PE). Sixty-five PE patients (32 males, mean age 58 ± 12 years) and 29 healthy controls (15 males, mean age 56 ± 14 years) were enrolled in the study. sCD40L levels were evaluated at the enrollment by ELISA method. Multislice detected pulmonary computed tomography was performed on all patients with a suspected diagnosis of PE. In addition, echocardiography was performed to evaluate right ventricular (RV) dysfunction. There was no statistically significant difference between the two groups regarding demographic features. sCD40L levels were significantly higher in acute PE group compared to healthy controls (5.3 ng/ml and 1.4 ng/ml, respectively; p < 0.001). sCD40L levels of patients with and without RV dysfunction were similar. Correlation analysis between echocardiographic findings and sCD40L levels did not show significant difference. The present study demonstrated a role of sCD40L in pathogenesis of PE for the first time. Further studies are needed to clarify a predictive and prognostic value of sCD40L levels in acute PE patients.

Heparin-induced thrombocytopenia associated with pulmonary embolism.

Type II heparin-induced thrombocytopenia (HIT) is a potentially severe adverse effect of heparin treatment triggered by an immune response. Although most cases occur in patients receiving unfractioned heparin, HIT can also arise after low-molecular-weight heparin (LMWH). We report a case of HIT in a postoperative orthopedic 75-year-old woman in treatment with LMWH (nadroparin) complicated by pulmonary embolism and treated successfully with recombinant hirudin. Early recognition and proper treatment are fundamental for the management of this life-threatening disorder.

Gender differences in chronic thromboembolic pulmonary hypertension in Japan.

BACKGROUND: The predominance of chronic thromboembolic pulmonary hypertension (CTEPH) in females and association of HLA-B*5201 with CTEPH have been reported in Japan. However, the clinical characteristics of female CTEPH remain uncertain. The purpose of the present study is to clarify the clinical phenotype of female CTEPH in Japan. METHODS AND RESULTS: The 150 consecutive patients (female 103, male 47; age 52.8+/-12.4 years SD) were admitted to Chiba University Hospital, and diagnosis was confirmed using right cardiac catheterization and pulmonary angiography. Among these patients, 78 underwent pulmonary endarterectomy. Clinical characteristics, pulmonary hemodynamics, extent of central disease and surgical outcome in females were compared with those in males. The female patients were elderly and had less deep vein thrombosis, less acute embolic episodes, better cardiac function, lower arterial oxygen tension and more peripheral thrombi, and showed less improvement through surgery than males. When the patients were identified using HLA-B*5201, HLA-B*5201-positive female patients had less embolic episodes and better cardiac function with lower operative mortality. In contrast, HLA-B*5201-negative female patients had less embolic episodes, and more peripheral thrombi, resulting in less improvement by surgery. CONCLUSION: The clinical phenotype of female CTEPH differed from that of male CTEPH. Additionally, gender differences of HLA-B*5201-positive type were dissimilar to those of HLA-B*5201-negative type.

Role of inflammation in right ventricular damage and repair following experimental pulmonary embolism in rats.

Right ventricular (RV) dysfunction is associated with poor clinical outcome following pulmonary embolism (PE). Previous studies in our laboratory show that influx of neutrophils contributes to acute RV damage seen in an 18 h rat model of PE. The present study describes the further progression of inflammation over 6 weeks and compares the neutrophil and monocyte responses. The RV outflow tract became white in colour by day 1 with influx of neutrophils (tissue myeloperoxidase activity increased 17-fold) and mononuclear cells with characteristics of M1 phenotype (high in Ccl20, Cxcl10, CcR2, MHCII, DNA microarray analysis). Matrix metalloproteinase activities were increased and tissue was thinned to produce a translucent appearance in weeks 1 through 6 in 40% of hearts. RV contractile function was significantly reduced at 6 weeks of PE. In this later phase, there was accumulation of myofibroblasts, the presence of mononuclear cells with M2 characteristics (high in scavenger mannose receptors, macrophage galactose lectin 1, PDGFR1, PDGFRbeta), enrichment of the subendocardial region of the RV outflow tract with neovesels (alpha-smooth muscle immunohistochemistry) and deposition of collagen fibres (picrosirius red staining) beginning scar formation. Thus, while neutrophil response is associated with the early, acute inflammatory events, macrophage cells continue to be present during the proliferative phase and initial deposition of collagen in this model, changing from the M1 to the M2 phenotype. This suggests that the macrophage cell response is biphasic.

Inhibition of CINC-1 decreases right ventricular damage caused by experimental pulmonary embolism in rats.

Right ventricular (RV) dysfunction is a strong risk factor for poor clinical outcome following pulmonary embolism (PE), the third most prevalent cardiovascular disease. Previous studies in our laboratory demonstrated that RV failure during PE is mediated, in part, by neutrophil-dependant cardiac inflammation. In this study we use DNA microarray analysis of gene expression to demonstrate that PE results in increased expression of the CXC chemokines CINC-1 and CINC-2 between 6 and 18 h after the start of PE in a rat model of PE. Neutrophils accumulate in RV tissue by 18 h, and this inflammation is associated with decreased right heart function. Treatment of rats with Abs to CINC-1 significantly suppressed neutrophil accumulation in RVs during PE (52% reduction in tissue myeloperoxidase) and ameliorated RV failure. In addition, plasma concentration of cardiac troponin I, an established diagnostic marker for cardiac damage, was reduced by 90%. These results suggest that selective anti-inflammatory therapies targeted at neutrophil chemoattractants will reduce cardiac inflammation and reduce RV damage in the setting of PE.

Pseudo-pulmonary embolism as a sign of acute heparin-induced thrombocytopenia in hemodialysis patients: safety of resuming heparin after disappearance of HIT antibodies.

Heparin-induced thrombocytopenia (HIT) is a syndrome caused by platelet-activating antibodies that recognize complexes of platelet factor 4 (PF4) and heparin. Thrombocytopenia is the most common clinical feature of HIT. HIT can be considered as a hypercoagulable state, with a high risk of thrombosis. Another feature of HIT is an acute systemic reaction that characteristically begins 5-30 min after receiving an intravenous bolus of unfractionated heparin, such as is commonly given for hemodialysis (HD). Here we present 4 patients who developed acute HIT at or near the start of their chronic HD. All patients were anticoagulated with the low-molecular-weight heparin, nadroparin, for HD. Three of our patients underwent surgery approximately 1-2 weeks before developing HIT. All patients presented with an acute systemic reaction during HD. All patients were treated and further dialyzed with lepirudin. Under this treatment we observed a quick recovery of the platelet count, and patients remained symptom-free. Antibodies against the PF4-heparin complex were detected with a combination of a 'quick test' and an enzyme-linked immunosorbent assay test. The likelihood of having HIT previous to the detection of antibodies was estimated with the pre-test probability score criteria. The tests for PF4-heparin antibodies remained positive for an average of 165 days. Three patients underwent a rechallenge with nadroparin after disappearance of the HIT antibodies in their serum. All 3 remained symptomless when they were further hemodialyzed on nadroparin. Our observations indicate that nadroparin can be successfully reintroduced for HD anticoagulation once the patient's HIT antibodies have disappeared.

A red blood cell autoantibody with mimicking anti-E specificity.

BACKGROUND: Uncommonly, antibodies that appear to exhibit antigenic specificity on red blood cell (RBC) panels fail to maintain specificity following alloadsorption (i.e., they mimic antigenic specificity). Understanding both the pitfalls and the proper pathways to establish the diagnosis and to interpret the clinical significance of these mimicking antibodies is important for patient management. CASE REPORT: A 68-year-old woman was admitted with dyspnea, anemia, bilateral pulmonary emboli, and metastatic ovarian cancer. Blood bank evaluation identified anti-E reactivity in the patient's plasma sample and a positive direct antiglobulin test (DAT). RESULTS: The DAT was positive for immunoglobulin G and negative for C3b. An eluate of the RBCs showed E-antigen specificity on a RBC antibody panel. Repeat serologic testing with RBC antibody panels with adsorbed patient plasma showed removal of apparent anti-E reactivity with either E-antigen-positive or E-antigen-negative RBC stroma. CONCLUSION: A mimicking autoantibody with apparent E-antigen specificity was identified in the plasma sample of a woman with newly diagnosed ovarian cancer. Despite their relative low frequency, mimicking antibodies, whether auto- or alloantibodies, may interfere with the timely issuance of compatible blood products and may confuse laboratory and clinical staff. Determining the clinical significance of the antibody, by taking into account the RBC phenotype of the patient and the antigen prevalence in the general population, guides the extent of workup required to best utilize resources while assuring patient safety.