Convalescent Plasma for Preventing Critical Illness in COVID-19: a Phase 2 Trial and Immune Profile.

The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an unprecedented event requiring frequent adaptation to changing clinical circumstances. Convalescent immune plasma (CIP) is a promising treatment that can be mobilized rapidly in a pandemic setting. We tested whether administration of SARS-CoV-2 CIP at hospital admission could reduce the rate of ICU transfer or 28-day mortality or alter levels of specific antibody responses before and after CIP infusion. In a single-arm phase II study, patients >18 years-old with respiratory symptoms with confirmed COVID-19 infection who were admitted to a non-ICU bed were administered two units of CIP within 72 h of admission. Levels of SARS-CoV-2 detected by PCR in the respiratory tract and circulating anti-SARS-CoV-2 antibody titers were sequentially measured before and after CIP transfusion. Twenty-nine patients were transfused high titer CIP and 48 contemporaneous comparable controls were identified. All classes of antibodies to the three SARS-CoV-2 target proteins were significantly increased at days 7 and 14 post-transfusion compared with baseline (P < 0.01). Anti-nucleocapsid IgA levels were reduced at day 28, suggesting that the initial rise may have been due to the contribution of CIP. The groups were well-balanced, without statistically significant differences in demographics or co-morbidities or use of remdesivir or dexamethasone. In participants transfused with CIP, the rate of ICU transfer was 13.8% compared to 27.1% for controls with a hazard ratio 0.506 (95% CI 0.165-1.554), and 28-day mortality was 6.9% compared to 10.4% for controls, hazard ratio 0.640 (95% CI 0.124-3.298). IMPORTANCE Transfusion of high-titer CIP to non-critically ill patients early after admission with COVID-19 respiratory disease was associated with significantly increased anti-SARS-CoV-2 specific antibodies (compared to baseline) and a non-significant reduction in ICU transfer and death (compared to controls). This prospective phase II trial provides a suggestion that the antiviral effects of CIP from early in the COVID-19 pandemic may delay progression to critical illness and death in specific patient populations. This study informs the optimal timing and potential population of use for CIP in COVID-19, particularly in settings without access to other interventions, or in planning for future coronavirus pandemics.

Convalescent plasma for preventing critical illness in COVID-19: A phase 2 trial and immune profile.

RATIONALE: The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an unprecedented event requiring rapid adaptation to changing clinical circumstances. Convalescent immune plasma (CIP) is a promising treatment that can be mobilized rapidly in a pandemic setting. OBJECTIVES: We tested whether administration of SARS-CoV-2 CIP at hospital admission could reduce the rate of ICU transfer or 28 day mortality. METHODS: In a single-arm phase II study, patients >18 years-old with respiratory symptoms documented with COVID-19 infection who were admitted to a non-ICU bed were administered two units of CIP within 72 hours of admission. Detection of respiratory tract SARS-CoV-2 by polymerase chain reaction and circulating anti-SARS-CoV-2 antibody titers were measured before and at time points after CIP transfusion. MEASUREMENTS AND MAIN RESULTS: Twenty-nine patients were transfused CIP and forty-eight contemporaneous controls were identified with comparable baseline characteristics. Levels of anti-SARS-CoV-2 IgG, IgM, and IgA anti-spike, anti-receptor-binding domain, and anti-nucleocapsid significantly increased from baseline to post-transfusion for all proteins tested. In patients transfused with CIP, the rate of ICU transfer was 13.8% compared to 27.1% for controls with a hazard ratio 0.506 (95% CI 0.165-1.554), and 28-day mortality was 6.9% compared to 10.4% for controls, hazard ratio 0.640 (95% CI 0.124-3.298). CONCLUSIONS: Transfusion of high-titer CIP to patients early after admission with COVID-19 respiratory disease was associated with reduced ICU transfer and 28-day mortality but was not statistically significant. Follow up randomized trials may inform the use of CIP for COVID-19 or future coronavirus pandemics.

Concordance of two polymerase chain reaction-based blood group genotyping platforms for patients with sickle cell disease.

CONCLUSIONS: In recent years, polymerase chain reaction-based genotyping platforms, which provide a predicted phenotype, have increased in both patient and high-throughput donor testing, especially in situations where serologic methods or reagents are limited. This study looks at the concordance rate between two platforms commercially available in the United States when used for testing samples from patients with sickle cell disease (SCD), a group particularly vulnerable to alloimmunization. DNA extracted from samples from 138 patients with SCD was tested by human erythrocyte antigen (HEA) BeadChip (Immucor, Norcross, GA) and by ID CORE XT (Progenika-Grifols, Barcelona, Spain). Predicted phenotype results were compared, and a concordance rate was calculated. Discrepancies were resolved by Sanger sequencing. All testing was done under an institutional review board-approved protocol. A concordance rate of 99.9 percent was obtained. Sanger sequencing was performed on four samples with discrepancies in the Rh blood group system. Three samples had a similar allelic variant detected by ID CORE XT. Two of the three discrepant samples were correctly identified as V+w, VS- by ID CORE XT but not by HEA BeadChip. The third sample, predicted to have a phenotype of V+, VS+ by sequencing, was called correctly by HEA BeadChip but not by ID CORE XT, which had predicted V+w, VS-. The fourth discrepancy was identified in a sample that ID CORE XT accurately identified as RHCE*ce[712G] and predicted a partial c phenotype. This result was confirmed by Sanger sequencing, whereas HEA BeadChip found no variants and predicted a c+ phenotype. The high concordance rate of the two methods, along with the known limitations of serology, warrant further discussion regarding the practice of serologic confirmation of extended phenotypes. Clinical significance of the identified discrepancies remains to be determined.

Red blood cell phenotype prevalence in blood donors who self-identify as Hispanic.

CONCLUSIONS: Molecular genotyping platforms provide a quick, high-throughput method for identifying red blood cell units for patients on extended phenotype-matching protocols, such as those with sickle cell disease or thalassemia. Most of the antigen prevalence data reported are for non-Hispanic populations. Therefore, this study sought to determine the phenotype prevalence in a single blood center's Hispanic population and to compare those results with previously reported rates in non-Hispanic donor populations. We performed a retrospective review of all serologic and molecular typing from donors who self-reported as Hispanic. The phenotype prevalence was reported and compared with rates from other racial/ethnic groups. A total of 1127 donors who selfidentified as Hispanic were screened by serologic methods for Rh and Kell antigens, and 326 were subsequently selected for molecular typing. The most prevalent probable Rh phenotypes were R1r (26.6%), R1R2 (21.5%), and R1R1 (20.7%); rr was found in 7.8 percent of donors tested. The percentage of K+ donors in this population was 2.8 percent. The most prevalent Duffy phenotypes were Fy(a+b+) (35.9%), Fy(a+b-) (35.6%), and Fy(a-b+) (27%). Of the donors studied, 15.3 percent had an FY GATA mutation. Only 1.5 percent of the donors were Fy(a-b-). The Jk(a+b+) phenotype was found in nearly half of the population. M+N+S+s+ was the most prevalent MNS phenotype from that group, constituting 22.4 percent. A total of 95.7 percent of the donors were Lu(a-b+), and Di(a-b+) was observed in 94.4 percent. The most prevalent Dombrock phenotype was Do(a+b+), constituting 46.9 percent, followed closely by Do(a-b+) at 40.5 percent. Hispanic donor antigen prevalence is distinctly different from other racial/ethnic groups and should be considered when attempting to find extended matched units for these patients.

Effects of storage duration and volume on the quality of leukoreduced apheresis-derived platelets: implications for pediatric transfusion medicine.

BACKGROUND: Platelet (PLT) storage adversely affects PLT structure and function in vitro and is associated with decreased PLT recovery and function in vivo. In pediatric transfusion medicine, it is not uncommon for small residual volumes to remain in parent units after aliquot preparation of leukoreduced apheresis-derived PLTs (LR-ADP). However, limited data exist regarding the impact of storage on residual small-volume LR-ADP. STUDY DESIGN AND METHODS: Standard metabolic testing was performed on residual volumes of LR-ADP after aliquot removal and PLT aggregometry using a dual agonist of ADP and collagen was performed on stored, small-volume aliquots (10-80mL) created from an in vitro model of PLT storage. RESULTS: Seventy-seven LR-ADP underwent metabolic (n=67) or metabolic and aggregation (n=10) studies. All products maintained a pH value of more than 6.89 throughout storage. Lactate and pCO(2) increased proportionally with longer storage time. Regardless of acceptable metabolism during storage, aggregation in 10- to 20-mL aliquots was impaired by Day 4 and aliquots less than 40 mL demonstrated the most dramatic decrease in aggregation from baseline. CONCLUSIONS: Despite maintenance of acceptable metabolic conditions, residual volumes of LR-ADP develop impaired aggregation in vitro that may adversely affect PLT survival and function in vivo. At volumes below 40mL, LR-ADP revealed reduced aggregation. As a result, it is recommended to monitor and record volumes of LR-ADP used for pediatric transfusion. Moreover, once LR-ADP attain a volume of 50mL or less on Day 4 or Day 5 of storage, consider discarding these products until their in vivo efficacy can be studied.

Effects of recombinant activated factor VII on thrombin-mediated feedback activation of coagulation.

Thrombin is a key hemostatic enzyme, which propagates its own generation by activating factors V, VIII, and XI. Sustained thrombin generation also activates thrombin-activatable fibrinolysis inhibitor (TAFI), which stabilizes fibrin clot against fibrinolysis. Recombinant activated factor VII (rFVIIa) is considered a novel hemostatic intervention for refractory bleeding, but rebleeding episodes related to fibrinolysis still occur. The present study aimed to investigate the antifibrinolytic effects of rFVIIa in relation to thrombin generation. Using thrombelastography, the effects of rFVIIa on thrombin-activated fibrin formation and on fibrinolysis induced by tissue plasminogen activator were evaluated in various factor-deficient plasma samples. A Thrombinoscope was used to quantitate thrombin generation. Thrombin increased antifibrinolytic activity in a concentration-dependent manner as demonstrated by a longer clot lysis time. In plasma deficient in factors V, VIII, IX, X, or XI, clot lysis occurred early (< 20 min), and rFVIIa addition had minimal effect, except for improved antifibrinolytic effect in factor-XI-deficient plasma. A normal clot lysis time was observed in factor-XIII-deficient or dual antithrombin/factor-VIII-deficient plasma. Inhibition of TAFI increased the rate of fibrinolysis. Thrombin generation was delayed or decreased in single factor-deficient plasma except for factor XIII deficiency. After rFVIIa addition, the peak thrombin generation reached over 100 nmol/l in factor-XI-deficient plasma, but not in plasma deficient in factors V, VIII, IX, or X. Thrombin generation and subsequent activation of TAFI were important for clot stability. We conclude that rFVIIa therapy does not compensate for increased susceptibility to fibrinolysis due to lack of factor(s) necessary for the formation of tenase and prothrombinase.

Antithrombin affects hemostatic response to recombinant activated factor VII in factor VIII deficient plasma.

BACKGROUND: Thromboembolic complications can occur with recombinant activated factor VII (rFVIIa) treatment in trauma and surgical patients but they are infrequent in hemophiliacs. Bleeding diathesis in these conditions is often attributed to reduced thrombin generation, which may be improved with rFVIIa. Normally, thrombin that diffuses from local vascular injury sites is quickly inactivated by antithrombin (AT). Evaluating the influence of AT levels on thrombin generation in hypocoagulable FVIII-deficient plasma would be a simple approach to better understand how procoagulant stimuli, such as rFVIIa, might result in postoperative thrombotic complications. We hypothesize that reduced AT concentrations would increase the procoagulant effects of rFVIIa in FVIII-deficient plasma. METHODS: Thrombin generation was evaluated in vitro in FVIII-deficient and AT/FVIII-deficient plasma using thrombelastography and a thrombin generation assay (Thrombinoscope). The effect of added rFVIIa on these variables was evaluated. RESULTS: Delayed thrombus formation based on thrombelastography in FVIII-deficient plasma was predictably reversed by rFVIIa. Improved thrombus formation and responses to rFVIIa were observed when AT levels were 20%-50% of normal. Thrombin generation in FVIII-deficient plasma increased in an inverse relationship to AT levels. Supplemental rFVIIa decreased the lag time of thrombin generation but not the amount of thrombin generated. CONCLUSIONS: Using FVIII-deficient plasma as a model of reduced thrombin generation, we demonstrate that low AT levels enhance in vitro hemostatic responses to rFVIIa. Reduced AT levels in trauma and surgical patients with normal or increased FVIII levels may be considered potentially prothrombotic. Monitoring of AT levels during rFVIIa therapy may thus reduce thrombotic complications in nonhemophiliacs.

Transfusion-related acute lung injury.

With the success of reducing the risk of transfusion-transmitted infectious diseases, noninfectious serious hazards of transfusion have come to the forefront with respect to transfusion safety. Transfusion-related acute lung injury has emerged as a dominant noninfectious serious hazard of transfusion. Improved understanding of its pathophysiology is needed to improve clinical strategies to deal with the risk. Such understanding, in turn, will depend on the continued progress in development of good model systems, in vitro and in vivo, for experimental studies. As the pathologic mechanisms are elucidated, a universal definition and strategies for the prevention and/or mitigation may become more tangible. This article reviews the clinical manifestations, evolving definition, incidence, pathophysiology, animal modeling, and donor screening and deferral algorithms as they relate to transfusion-related acute lung injury.