Familial autoimmunity and risk of developing immune thrombocytopenia and Evans syndrome.

BACKGROUND: Immune thrombocytopenia (ITP) and Evans syndrome (ES) are manifestations of immune dysregulation. Genetic variants in immune-related genes have been identified in patients with ITP and especially ES. We aimed to explore familial autoimmunity in patients with ITP and ES to understand possible contributions to chronicity. PROCEDURE: We assessed family history in two ways: via patient report for ITP and ES and by population-based analysis using the Utah Population Database (UPDB) for ITP. A total of 266 patients with ITP and 21 patients with ES were identified via chart review, and 252 of the 266 patients with ITP were also identified in the UPDB. RESULTS: Chart review showed familial autoimmunity in 29/182 (15.9%) and 25/84 (29.8%) of patients with newly diagnosed+persistent (nd+p) ITP and chronic ITP (cITP), respectively, (p = .009). The UPDB analysis revealed that autoimmunity in relatives of patients with nd+pITP was higher than in relatives of controls (odds ratio [OR]: 1.69 [1.19-2.41], p = .004), but was not significantly increased in relatives of patients with cITP (OR 1.10 [0.63-1.92], p = .734). Incomplete family history in medical records likely contributed to the observed discrepancy. CONCLUSIONS: The findings suggest that familial autoimmunity may have a stronger association with the development of ITP rather than its duration. Twelve (57.1%) patients with ES reported autoimmunity in their relatives. UPDB analysis was omitted due to the small number of patients with ES. The use of population databases offers a unique opportunity to assess familial health and may provide clues about contributors to immune dysregulation features within families.

Maturing neutrophils of lower density associate with thrombocytopenia in Puumala orthohantavirus-caused hemorrhagic fever with renal syndrome.

Puumala orthohantavirus-caused hemorrhagic fever with renal syndrome (PUUV-HFRS) is characterized by strong neutrophil activation. Neutrophils are the most abundant immune cell type in the circulation and are specially equipped to rapidly respond to infections. They are more heterogenous than previously appreciated, with specific neutrophil subsets recently implicated in inflammation and immunosuppression. Furthermore, neutrophils can be divided based on their density to either low-density granulocytes (LDGs) or "normal density" polymorphonuclear cell (PMN) fractions. In the current study we aimed to identify and characterize the different neutrophil subsets in the circulation of PUUV-HFRS patients. PMNs exhibited an activation of antiviral pathways, while circulating LDGs were increased in frequency following acute PUUV-HFRS. Furthermore, cell surface marker expression analysis revealed that PUUV-associated LDGs are primarily immature and most likely reflect an increased neutrophil production from the bone marrow. Interestingly, both the frequency of LDGs and the presence of a "left shift" in blood associated with the extent of thrombocytopenia, one of the hallmarks of severe HFRS, suggesting that maturing neutrophils could play a role in disease pathogenesis. These results imply that elevated circulating LDGs might be a general finding in acute viral infections. However, in contrast to the COVID-19 associated LDGs described previously, the secretome of PUUV LDGs did not show significant immunosuppressive ability, which suggests inherent biological differences in the LDG responses that can be dependent on the causative virus or differing infection kinetics.

Association of Metal Cations with the Anti-PF4/Heparin Antibody Response in Heparin-Induced Thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is an antibody-mediated immune response against complexes of heparin and platelet factor 4 (PF4). The electrostatic interaction between heparin and PF4 is critical for the anti-PF4/heparin antibody response seen in HIT. The binding of metal cations to heparin induces conformational changes and charge neutralization of the heparin molecule, and cation-heparin binding can modulate the specificity and affinity for heparin-binding partners. However, the effects of metal cation binding to heparin in the context of anti-PF4/heparin antibody response have not been determined. Here, we utilized inductively coupled plasma mass spectrometry (ICP-MS) to quantify 16 metal cations in patient plasma and tested for correlation with anti-PF4/heparin IgG levels and platelet count after clinical suspicion of HIT in a cohort of heparin-treated patients. The average age of the cohort (n = 32) was 60.53 (SD = 14.31) years old, had a mean anti-PF4/heparin antibody optical density [OD405] of 0.93 (SD = 1.21) units, and was primarily female (n = 23). Patients with positive anti-PF4/heparin antibody test results (OD405 ≥ 0.5 units) were younger, had increased weight and BMI, and were more likely to have a positive serotonin release assay (SRA) result compared to antibody-negative patients. We observed statistical differences between antibody-positive and -negative groups for sodium and aluminum and significant correlations of anti-PF4/heparin antibody levels with sodium and silver. While differences in sodium concentrations were associated with antibody-positive status and correlated with antibody levels, no replication was performed. Additional studies are warranted to confirm our observed association, including in vitro binding studies and larger observational cohorts.

Combination of 2 Quantitative Immunoassays and Clinical Score Algorithm to Reduce False-Negative Results in Heparin-Induced Thrombocytopenia: Prevalence Study of Mauriziano Hospital in Turin, Italy.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a serious adverse effect of heparin treatment caused by platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies. Accurate diagnosis of HIT is essential but remains challenging. The aim of our study was to explore the performance of our optimized diagnostic laboratory algorithm, based on Chemiluminescence (CliA) and ELISA immunoassays, on suspected HIT patients. The study compared the prevalence of HIT diagnosis in A.O. Mauriziano with the literature. METHODS: 163 consecutive patients were investigated for suspected HIT with CliA HemosIL Acustar HIT-IgG, Werfen. HIT was ruled out in all patients with CliA <0.13 U/mL. All patients with CliA >0.13 U/mL were further investigated with Zymutest-HIA anti-PF4 IgG ELISA immunoassay. In these patients, HIT was ruled out on the combination of CliA between 0.13 and 1.0 U/mL followed by ELISA assay <0.300 OD. HIT was ruled in patients whose plasma tested positive or doubtful with CliA and positive with ELISA immunoassay and confirmed positive with a platelet aggregation test (PAT). Suspicion of HIT was revealed with clinical 4Ts score or recent suggestive anamnestic history. RESULTS: Our diagnostic algorithm ruled out HIT diagnosis in 144/163 patients (88%) and predicted a positive PAT in 5/19 (26%) of CliA positive (4/5) or ELISA positive and CliA doubtful (1/5) patients. CONCLUSIONS: Our prevalence was 3.1%, comparable with the literature. The approach combining 2 quantitative immunoassays' (CliA and ELISA) results and 4Ts score probability was able to rule out the diagnosis within 1 h in 66% of patients with suspected HIT and within 24 h in 88% of patients. In the remaining 12% of cases, management decisions have to be based on individualized judgment while awaiting functional confirming results (48-72 h).

Flow cytometry vs conventional methods for the evaluation of anti-PF4/heparin antibodies: a single center study.

Aim: Heparin-induced thrombocytopenia (HIT) is a rare, life-threatening, immune-mediated adverse effect of heparin administration. This study compares frequently used laboratory assays in terms of their effectiveness in HIT diagnosis.Materials & methods: Fifty patients with suspected HIT were tested by gel immunoassay and solid phase PF4/heparin antibody ELISA. On positive results, platelet activation markers P-selectin and Annexin V were assayed using flow cytometry.Results: Thirty/50 patients were negative for both immunoassays. Flow cytometry was performed in the 20 immunoassay positive patients. Platelet activation was observed in 7/20 in the presence of low heparin concentration (0.2 IU/ml).Conclusion: The results are in accordance with the currently available literature and flow cytometry seems a promising alternative in HIT laboratory investigation.

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Recurrent Cerebral Hemorrhaging with Platelet Dysfunction Accompanied by Anti-glycoprotein VI Autoantibodies in a Patient with TAFRO Syndrome.

Thrombocytopenia, anasarca, fever, renal dysfunction, and organomegaly (TAFRO) syndrome is an inflammatory disorder with an unclear pathogenesis. We herein report a case of TAFRO syndrome in remission in a patient who experienced recurrent intracranial bleeding despite a normal platelet count and coagulation system. A further investigation suggested the presence of anti-glycoprotein VI (GPVI) autoantibodies in the plasma, which induced platelet dysfunction and bleeding tendency. No new bleeding or relapse of TAFRO syndrome occurred after immunosuppressive therapy was initiated. These findings may help elucidate the autoimmune pathogenesis of TAFRO syndrome.

Hypogammaglobulinemia and Anti-CD20 Therapy-Induced Acute Thrombocytopenia: Perhaps More than a Coincidence?

INTRODUCTION: The development of secondary hypogammaglobulinemia (sHGG) because of tumor treatment and/or the primary underlying hematologic disorder holds substantial clinical significance. B-cell-derived malignancies and anti-CD20 monoclonal antibodies (mAbs) represent important risk factors for the development of sHGG. In addition, the occurrence of acute thrombocytopenia (AT) induced by anti-CD20 therapy is a known, albeit rare, phenomenon. CASE PRESENTATION: A 54-year-old patient experiencing the first relapse of classical follicular lymphoma has commenced salvage therapy following the R-DHAP protocol. After rituximab infusion, platelet count dropped from 116 × 109/L to 13 × 109/L within 24 h. Reduced immunoglobulin G levels indicated moderate HGG; thus, we immediately administered intravenous immunoglobulins (IVIg). Within 5 days after initiation of IVIg, platelet count increased and stabilized at >50 × 109/L. CONCLUSIONS: It seems possible that anti-CD20 mAbs act like or activate similar mechanisms as autoantibodies in immune thrombocytopenia (ITP). Assuming that anti-CD20 therapy-induced AT is an ITP-like condition, HGG could be considered a potential risk factor. Thus, appropriate treatment of HGG with IVIg prior to anti-CD20 mAb therapy could potentially alleviate anti-CD20 therapy-induced AT.

Prolonged cytopenias after immune effector cell therapy and lymphodepletion in patients with leukemia, lymphoma and solid tumors.

BACKGROUND AIMS: The success of chimeric antigen receptor (CAR) T-cell therapy in treating B-cell malignancies has led to the evaluation of CAR T-cells targeting a variety of other malignancies. Although the efficacy of CAR T-cells is enhanced when administered post-lymphodepleting chemotherapy, this can trigger bone marrow suppression and sustained cytopenia after CD19.CAR T-cell therapy. Additionally, systemic inflammation associated with CAR T-cell activity may contribute to myelosuppression. Cytopenias, such as neutropenia and thrombocytopenia, elevate the risk of severe infections and bleeding, respectively. However, data on the incidence of prolonged cytopenias after immune effector therapy in the solid tumor context remain limited. OBJECTIVE: We compared the incidence of prolonged cytopenias after immune effector therapy including genetically modified T-cells, virus-specific T-cells (VSTs) and NKT-cells, as well non-gene-modified VSTs for leukemia, lymphoma, and solid tumors (ST) to identify associated risk factors. METHODS: A retrospective analysis was conducted of 112 pediatric and adult patients with relapsed and/or refractory cancers who received lymphodepleting chemotherapy followed by immune effector therapy. Patients treated with 13 distinct immune effector cell therapies through 11 single-center clinical trials and 2 commercial products over a 6-year period were categorized into 3 types of malignancies: leukemia, lymphoma and ST. We obtained baseline patient characteristics and adverse events data for each participant, and tracked neutrophil and platelet counts following lymphodepletion. RESULTS: Of 112 patients, 104 (92.9%) experienced cytopenias and 88 (79%) experienced severe cytopenias. Patients with leukemia experienced significantly longer durations of severe neutropenia (median duration of 14 days) compared with patients with lymphoma (7 days) or ST (11 days) (P = 0.002). Patients with leukemia also had a higher incidence of severe thrombocytopenia (74.1%), compared with lymphoma (46%, P = 0.03) and ST (14.3%, P < 0.0001). Prolonged cytopenias were significantly associated with disease type (63% of patients with leukemia, 44% of patients with lymphoma, and 22.9% of patients with ST, P = 0.006), prior hematopoietic stem cell transplant (HSCT) (66.7% with prior HSCT versus 38.3% without prior HSCT, P = 0.039), and development of immune effector cell-associated neurotoxicity syndrome (ICANS) (75% with ICANS versus 38% without ICANS, P = 0.027). There was no significant association between prolonged cytopenias and cytokine release syndrome. CONCLUSIONS: Immune effector recipients often experience significant cytopenias due to marrow suppression following lymphodepletion regardless of disease, but prolonged severe cytopenias are significantly less common after treatment of patients with lymphoma and solid tumors.

L-plastin associated syndrome of immune deficiency and hematologic cytopenia.

BACKGROUND: LCP1 encodes L-plastin, an actin-bundling protein primarily expressed in hematopoietic cells. In mouse and fish models, LCP1 deficiency has been shown to result in hematologic and immune defects. OBJECTIVE: This study aimed to determine the nature of a human inborn error of immunity resulting from a novel genetic variant of LCP1. METHODS: We performed genetic, protein, and cellular analysis of PBMCs from a kindred with apparent autosomal dominant immune deficiency. We identified a candidate causal mutation in LCP1, which we evaluated by engineering the orthologous mutation in mice and Jurkat cells. RESULTS: A splice-site variant in LCP1 segregated with lymphopenia, neutropenia, and thrombocytopenia. The splicing defect resulted in at least 2 aberrant transcripts, producing an in-frame deletion of 24 nucleotides, and a frameshift deletion of exon 8. Cellular analysis of the kindred revealed a proportionate reduction of T and B cells and a mild expansion of transitional B cells. Similarly, mice carrying the orthologous genetic variant exhibited the same in-frame aberrant transcript, reduced expression Lcp1 and gene dose-dependent leukopenia, mild thrombocytopenia, and lymphopenia, with a significant reduction of T-cell populations. Functional analysis revealed that LCP1c740-1G>A confers a defect in platelet development and function with aberrant spreading on collagen. Immunologic analysis revealed defective actin organization in T cells, reduced migration of PBMCs from patients, splenocytes from mutant mice, and a mutant Jurkat cell line in response to CXCL12; impaired germinal center B-cell expansion after immunization; and reduced cytokinesis during T cell proliferation. CONCLUSIONS: We describe a unique human hematopoietic defect affecting neutrophils, lymphocytes, and platelets arising from partial LCP1 deficiency.

Pattern of cytopenias and systemic immune-inflammation index among hospitalised patients of COVID-19.

OBJECTIVE: To compare the extent of cytopenias and systemic immune inflammation index of hospitalised coronavirus disease-2019 patients during the first and second/third waves of the pandemic. Methods: The retrospective, cross-sectional study was conducted in October 2021 at Fatima Memorial Hospital, Lahore, Pakistan, and comprised data of hospitalised coronavirus disease-2019 patients regardless of age and gender from May 2020 to June 2021. Data was segregated into first wave that lasted from May to July 2020, second wave that lasted from early November to mid-December 2020, and third wave that ranged from mid-March to June 2021. For comparison purposes, the data of first wave was in group A, while data of second and third waves was pooled into group B. Age, gender, comorbidities, requirement of ventilator support and outcome of the patients was noted. Inflammatory markers were compared on the basis of complete blood count and systemic immune-inflammation index data. Data was analysed using SPSS 25. RESULTS: Of the 202 patients, 90(44.5%) were in group A and 112(55.4%) were in group B. There were 108(53.5%) males and 94(46.5%) females. The median age in males was 58 years (interquartile range: 21 years) and it was 56 years (interquartile range: 21 years) in females. Neutrophilia (p<0.001), leukocytosis (p<0.001) and lymphocytopenia (p<0.001) had direct association with increased systemic immune-inflammation. Raised systemic immune-inflammation also had an association with increased requirement of ventilator support (p=0.2) and increased mortality (p=0.001). There were more females, more critical patients, more patients with anaemia, leukopenia, lymphocytopenia and thrombocytopenia in group B compared to group A (p<0.05). Need for ventilator support and mortality were also higher in group B compared to group A (p<0.05). Conclusion: All the indicators analysed were worse during the second and third waves of coronavirus disease-2019 compared to the first wave of the pandemic.

Serum proteomics reveals hemophagocytic lymphohistiocytosis-like phenotype in a subset of patients with multisystem inflammatory syndrome in children.

Children with Multisystem Inflammatory Syndrome in Children (MIS-C) can present with thrombocytopenia, which is a key feature of hemophagocytic lymphohistiocytosis (HLH). We hypothesized that thrombocytopenic MIS-C patients have more features of HLH. Clinical characteristics and routine laboratory parameters were collected from 228 MIS-C patients, of whom 85 (37%) were thrombocytopenic. Thrombocytopenic patients had increased ferritin levels; reduced leukocyte subsets; and elevated levels of ASAT and ALAT. Soluble IL-2RA was higher in thrombocytopenic children than in non-thrombocytopenic children. T-cell activation, TNF-alpha and IFN-gamma signaling markers were inversely correlated with thrombocyte levels, consistent with a more pronounced cytokine storm syndrome. Thrombocytopenia was not associated with severity of MIS-C and no pathogenic variants were identified in HLH-related genes. This suggests that thrombocytopenia in MIS-C is not a feature of a more severe disease phenotype, but the consequence of a distinct hyperinflammatory immunopathological process in a subset of children.

Investigation of the correlation between platelet antibodies and peripheral blood cytopenia in patients with hepatocellular carcinoma.

The primary triggers that stimulate the body to generate platelet antibodies via immune mechanisms encompass events such as pregnancy, transplantation, and blood transfusion. Interestingly, our findings revealed that a subset of male patients with hepatocellular carcinoma (HCC), despite having no history of transplantation or blood transfusion, has shown positive results in platelet antibody screenings. This hints at the possibility that certain factors, potentially related to the tumor itself or its treatment, may affect antibody production. To delve the causes we initiated this study. We employed a case-control study approach to analyze potential influential factors leading to the positive results via univariate and multivariate regression analysis. We utilized Kendall's tau-b correlation to examine the relationship between the strength of platelet antibodies and peripheral blood cytopenia. Antitumor medication emerged as an independent risk factor for positive results in HCC patients, and the strength of platelet antibodies positively correlated with the severity of anemia and thrombocytopenia. Without history of blood transfusion, transplantation, pregnancy, those HCC patients underwent recent tumor medication therapy are experiencing peripheral erythrocytopenia or thrombocytopenia, for them platelet antibody screenings holds potential clinical value for prevention and treatment of complications like drug-immune-related anemia and/or bleeding.

Therapeutic strategies in FcγIIA receptor-dependent thrombosis and thromboinflammation as seen in heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombocytopenia and thrombosis (VITT).

INTRODUCTION: Fcγ-receptors (FcγR) are membrane receptors expressed on a variety of immune cells, specialized in recognition of the Fc part of immunoglobulin G (IgG) antibodies. FcγRIIA-dependent platelet activation in platelet factor 4 (PF4) antibody-related disorders have gained major attention, when these antibodies were identified as the cause of the adverse vaccination event termed vaccine-induced immune thrombocytopenia and thrombosis (VITT) during the COVID-19 vaccination campaign. With the recognition of anti-PF4 antibodies as cause for severe spontaneous and sometimes recurrent thromboses independent of vaccination, their clinical relevance extended far beyond heparin-induced thrombocytopenia (HIT) and VITT. AREAS COVERED: Patients developing these disorders show life-threatening thromboses, and the outcome is highly dependent on effective treatment. This narrative literature review summarizes treatment options for HIT and VITT that are currently available for clinical application and provides the perspective toward new developments. EXPERT OPINION: Nearly all these novel approaches are based on in vitro, preclinical observations, or case reports with only limited implementation in clinical practice. The therapeutic potential of these approaches still needs to be proven in larger cohort studies to ensure treatment efficacy and long-term patient safety.

Anti-E alloimmunization from a platelet apheresis transfusion in a 22-month-old male with acute myeloid leukemia.

RhD alloimmunization from platelet transfusions have been documented in the literature. However, non-RhD platelet alloimmunization is much less frequent and the risk for non-RhD alloimmunization from platelets is thought to be extremely low and most associated with buffy coat pooled platelets. A 22-month-old male with acute myeloid leukemia received 99 mL apheresis platelets for thrombocytopenia. Three months later, an antibody screen, the direct antiglobulin test (DAT), and red blood cell (RBC) genotype were sent for laboratory evaluation. The antibody screen was positive, with anti-E identified. The DAT was negative and the RBC genotype of the patient was predicted to be negative for the E antigen whereas the platelet donor was predicted to be positive for E antigen. There is a risk of alloimmunization of non-RhD antigen from platelet pheresis transfusion even in a patient less than 2 years old.

Results of an international survey of opinions on the definitions and treatments for heparin-induced thrombocytopenia: communication from the ISTH SSC Subcommittee on Platelet Immunology.

Heparin-induced thrombocytopenia (HIT) is rare, affecting fewer than 1 in 1500 hospital admissions. Despite the increasing adoption of new therapies in HIT, such as direct oral anticoagulants and pooled immunoglobulins, there is limited high-quality evidence to guide clinicians. Numerous uncommon presentations of HIT and HIT-like entities have recently been recognized, and a harmonized approach to their classification is required to study them better. We present the results of an international survey of opinions from experts and practitioners in the field of platelet immunology regarding the role of direct oral anticoagulants in HIT, novel definitions of subclassifications of HIT-like platelet factor 4 immune conditions (spontaneous autoimmune HIT, persistent autoimmune HIT, and treatment-refractory HIT), and the role for intravenous immunoglobulins in the treatment paradigm of HIT and these HIT-like conditions. From 102 survey responses, there was broad acceptance of rivaroxaban (74.5%) and apixaban (73.5%) even before platelet recovery, as well as for intravenous immunoglobulin in the management of spontaneous (85.6%), persistent (83.7%), and treatment-refractory HIT (87.4%). With this mandate for harmonizing terminologies and treatment approaches in special situations without robust clinical data owing to their rarity, we plan to conduct a robust survey, establish international consensus, and draft management guidelines for HIT and platelet factor 4 immune diseases in the near future.

Immunologic Effects of Heparin Associated With Hemodialysis: Focus on Heparin-Induced Thrombocytopenia.

Intermittent hemodialysis (HD) is almost invariably performed with heparin, and thus HD patients are at risk of developing the immune-mediated adverse effect heparin-induced thrombocytopenia (HIT), caused by anti-platelet factor 4/heparin IgG, which strongly activates platelets. HIT patients develop hypercoagulability with greatly increased risk of thrombosis, both venous and arterial. Certain HIT-associated complications are more likely to develop among HD patients, including hemofilter thrombosis despite heparin, intravascular catheter and/or arteriovenous fistula-associated thrombosis, post-heparin bolus anaphylactoid/anaphylactic reactions, and thrombotic stroke and acute limb artery thrombosis (reflecting the high frequency of underlying arteriopathy in many patients with renal failure). Management of HIT in HD usually requires use of an alternative (non-heparin) anticoagulant; for example, danaparoid sodium (outside the USA) or argatroban (USA and elsewhere). Whether heparin-grafted hemodialyzers (without systemic heparin) can be used safely in acute HIT is unknown. The HIT immune response is remarkably transient and usually not retriggered by subsequent heparin administration. Accordingly, since renal failure patients often require long-term HD, there may be the opportunity-following seroreversion (loss of platelet-activating HIT antibodies)-to restart heparin for HD, a practice that appears to have a low likelihood of retriggering HIT.