Neutrophil Extracellular Traps (NETs) are large neutrophil-derived structures composed of decondensed chromatin, cytosolic, and granule proteins. NETs play an important role in fighting infection, inflammation, thrombosis, and tumor progression processes, yet their fast and reliable identification has been challenging. Smudge cells (SCs) are a subcategory of white cells identified by CellaVision^®, a hematology autoanalyzer routinely used in clinical practice that uses digital imaging to generate “manual” differentials of peripheral blood smears. We hypothesize that a proportion of cells identified in the SC category by CellaVision^® Hematology Autoanalyzers are actually NETs. We demonstrate that NET-like SCs are not present in normal blood samples, nor are they an artifact of smear preparation. NET-like SCs stain positive for neutrophil markers such as myeloperoxidase, leukocyte alkaline phosphatase, and neutrophil elastase. On flow cytometry, cells from samples with high percent NET-like SCs that are positive for surface DNA are also positive for CD45, myeloperoxidase and markers of neutrophil activation and CD66b. Samples with NET-like SCs have a strong side fluorescent (SFL) signal on the white count and nucleated red cells (WNR) scattergram, representing cells with high nucleic acid content. When compared to patients with low percent SCs, those with a high percentage of SCs have a significantly higher incidence of documented bacterial and viral infections. The current methodology of NET identification is time-consuming, complicated, and cumbersome. In this study, we present data supporting identification of NETs by CellaVision^®, allowing for easy, fast, cost-effective, and high throughput identification of NETs that is available in real time and may serve as a positive marker for a bacterial or viral infections.

Objectives: Heparin-induced thrombocytopenia (HIT) is a rare but life-threatening condition that requires rapid diagnosis for proper management. Laboratory testing should only be performed on patients with intermediate- or high-risk pretest probability. The platelet factor 4 (PF4) enzyme-linked immunosorbent assay (ELISA) is the screening test that should be confirmed by higher specificity testing such as the heparin-induced platelet aggregation (HIPA) or the serotonin release assay (SRA). This study aims to evaluate the performance of the HIPA in comparison to the SRA, establish cutoffs of the PF4 ELISA to predict positivity for HIPA/SRA, and study the mortality rate between patients with suspected HIT confirmed as HIT positive vs negative. Methods: All positive PF4 ELISA cases with confirmatory HIPA and SRA testing were included. As the SRA was considered the gold standard, the HIPA performance was evaluated in comparison to SRA before and after the implementation of a new standardized interpretation guide in 2022. The mortality of these cases was also documented by chart reviews. Results: In total, 232 cases with positive or indeterminate anti-PF4 IgG ELISA had confirmatory testing with HIPA and SRA. The sensitivity of the HIPA improved from 55.4% in 2018 to 2021 to 73.8% in 2022. The specificity remained similarly high in 2018 to 2021 vs 2022 (94.9% vs 87.5%). The negative predictive value (NPV) improved in 2022. The PF4 optical density cutoff to predict the positivity of SRA was 0.85 vs 1.47 to predict the positivity of HIPA but decreased to 0.83 when combining HIPA and/or SRA. There was no significant difference in mortality between patients with suspected HIT confirmed positive vs negative. Conclusions: Although the HIPA has a lower sensitivity than the SRA, the new standardized interpretation guide improved its sensitivity and NPV in 2022. Future improvements are needed to use the HIPA as a stand-alone confirmatory test with the goal to shorten hospital length of stay and expedite proper anticoagulation management.

Importance: COVID-19 has caused a worldwide illness and New York has become the epicenter of COVID-19 in the United States. Currently Bronx has the highest prevalence per capita in New York. Objective: To investigate the coagulopathic presentation of COVID and its natural course and to investigate whether hematologic and coagulation parameters can be used to assess illness severity and death. Design: Retrospective case study of positive COVID inpatients between 3/20/2020-3/31/2020. Setting: Montefiore Health System main hospital, Moses, a large tertiary care center in the Bronx. Participants: Adult inpatients with positive COVID tests hospitalized at MHS. Exposure (for observational studies): Datasets of participants were queried for physiological, demographic (age, sex, socioeconomic status and self-reported race and/or ethnicity) and laboratory data. Main Outcome and Measures: Relationship and predictive value of measured parameters to mortality and illness severity. Results: Of the 217 in this case review, 70 died during hospitalization while 147 were discharged home. Only the admission PT and first D-Dimer could very significantly differentiate those who were discharged alive and those who died. Logistic regression analysis shows increased odds ratio for mortality by first D-Dimer within 48 hrs. of admission. The optimal cut-point for the initial D-Dimer to predict mortality was found to be 1.65 μg/mL Conclusions: We describe here a comprehensive assessment of hematologic and coagulation parameters in COVID and examine the relationship of these to mortality. We demonstrate that both initial and maximum D-Dimer values are biomarkers that can be used for survival assessments.

Autops Case Rep, vol.11, e2021307, 2021