An in vitro comparison of intra-operative isohemagglutinin and human leukocyte antigen removal techniques in pediatric heart transplantation.

BACKGROUND: Highly sensitized pediatric patients awaiting heart transplantation experience longer wait times and thus higher waitlist mortality. Similarly, children less than 2 years of age have increased waitlist times and mortality when compared to their older peers. To improve the likelihood of successful transplantation in these patients, various strategies have been utilized, including peri-operative plasmapheresis. However, limited data exists comparing plasmapheresis techniques for antibody reduction. This study's aim was to compare the in vitro magnitude of isohemagglutinin titers (IT) and human leukocyte antigen (HLA) antibody removal and the time required between membrane-based plasmapheresis (MP) and centrifuge-based plasmapheresis (CP) incorporated into the extracorporeal (EC) circuit. METHODS: Two MP (Prismaflex) and two CP (Spectra Optia, Terumo BCT) circuits were incorporated into four separate EC circuits primed with high titer, highly sensitized type O donor whole blood. Assays were performed to determine baseline IT and anti-HLA antibodies and then at 30-minute increments until completion of the run (two plasma volume exchanges) at two hours. RESULTS: There was a decrease in anti-A and anti-B IgM and IgG titers with both MP and CP. Mean anti-A and anti-B titer reduction was by 4.625 titers (93.7% change) and 4.375 titers (93.8% change) using MP and CP, respectively. At 2 h of apheresis, CP reduced 62.5% of all ITs to ≤ 1:4, while MP reduced 50% of ITs to ≤ 1:4. Additionally, reduction of anti-HLA class II antibody to mean fluorescence intensity (MFI) <3000 was achieved with both MP and CP. At 2 h of apheresis, CP reduced MFI by 2-3.5 fold and MP reduced MFI by 1.7-2.5 fold. Both demonstrated similar hemolytic and thrombotic profiles. CONCLUSIONS: In this in vitro plasmapheresis model of IT and anti-HLA antibody reduction, both MP and CP incorporated into the EC circuit can be used quickly and effectively to reduce circulating antibodies. While CP may have some greater efficiency, further study is necessary to verify this in vivo.

Lessons learned from the use of convalescent plasma for the treatment of COVID-19 and specific considerations for immunocompromised patients.

Coronavirus disease 2019 (COVID-19) convalescent plasma (CovCP) infusions have been widely used for the treatment of hospitalized patients with COVID-19. The aims of this narrative review were to analyze the safety and efficacy of CovCP infusions in the overall population and in immunocompromised patients with COVID-19 and to identify the lessons learned concerning the use of convalescent plasma (CP) to fill treatment gaps for emerging viruses. Systematic searches (PubMed, Scopus, and COVID-19 Research) were conducted to identify peer-reviewed articles and pre-prints published between March 1, 2020 and May 1, 2021 on the use of CovCP for the treatment of patients with COVID-19. From 261 retrieved articles, 37 articles reporting robust controlled studies in the overall population of patients with COVID-19 and 9 articles in immunocompromised patients with COVID-19 were selected. While CovCP infusions are well tolerated in both populations, they do not seem to improve clinical outcomes in critically-ill patients with COVID-19 and no conclusion could be drawn concerning their potential benefits in immunocompromised patients with COVID-19. To be better prepared for future epidemics/pandemics and to evaluate potential benefits of CP treatment, only CP units with high neutralizing antibodies (NAbs) titers should be infused in patients with low NAb titers, patient eligibility criteria should be based on the disease pathophysiology, and measured clinical outcomes and methods should be comparable across studies. Even if CovCP infusions did not improve clinical outcomes in patients with COVID-19, NAb-containing CP infusions remain a safe, widely available and potentially beneficial treatment option for future epidemics/pandemics.

COVID-19 convalescent plasma donor characteristics, product disposition, and comparison with standard apheresis donors.

BACKGROUND: With coronavirus disease 2019 (COVID-19) convalescent plasma (CCP) offering an early treatment option for COVID-19, blood collectors needed to quickly overcome obstacles to recruiting and qualifying eligible donors. We provide attributes of CCP donors and products and compare to standard donors and products. STUDY DESIGN AND METHODS: Information on CCP donors was gathered from the American Red Cross qualification website through product collection. Data from 2019 for standard plasma/platelet apheresis (SA) and whole blood (WB) donor demographics and SA donations including product disposition and reactions were used for comparison. RESULTS: Of almost 59 000 donors registering on the website, 75% reported an existing COVID-19 diagnostic polymerase chain reaction or an antibody test. The majority (56.2%) of 10 231 CCP donors were first-time donors in contrast to SA or WB donor populations, which were only 3.0% and 30.6%, respectively, first-time donors. The number of female donors was 12% higher than SA donors. Older (≥ 65 years) and younger (16-19 years) were comparatively underrepresented in CCP donors. Deferral (10.2%) and Quantity Not Sufficient rates (6.4%) for presenting CCP donations were higher than SA (8.2% and 1.1%, respectively). Human leukocyte antigen antibody reactivity was the highest cause of product loss for CCP donations vs SA donations (9.6% vs 1.3%). Acute adverse events also occurred at a higher rate among both first-time and repeat CCP donations compared to SA. CONCLUSIONS: CCP donors were more likely to be first-time and female donors than WB or SA donors. CCP donations had a higher rate of donor adverse reactions, deferrals, and product loss than SA donations.

Neonatal and pediatric blood bank practice in the United States: Results from the AABB pediatric transfusion medicine subsection survey.

BACKGROUND: There are limited standards guiding the selection and processing of blood components specific for neonatal and pediatric transfusions. Therefore, blood banks (BBs) and transfusion services must create their own policies and procedures. STUDY DESIGN AND METHODS: The American Association of Blood Banks (AABB) Pediatric Transfusion Medicine Subsection Committee developed a 74-question survey to capture neonatal and pediatric BB practices in the United States. RESULTS: Thirty-five centers completed the survey: a response rate 15.8%. Responses indicated that most carry a mixed inventory of red blood cells (RBCs); 94.2% allow more than one type of RBC product for small-volume (SV) and large-volume (LV) transfusions to neonatal and pediatric patients. Many had storage age thresholds for RBCs transfused to neonates (SV = 60%, LV = 67.7%) but not older pediatric patients. The use of Group O for nonurgent RBC transfusion in neonates was common (74.2%). Responses related to special processing of RBCs and platelets indicated that 100% RBC and platelets are leukocyte-reduced (LR) for neonates and 97% for non-neonates. Irradiation of RBCs and platelets was commonly performed for neonatal transfusion (88.6%). Providing cytomegalovirus (CMV) seronegative products, volume reduction, and washing were variable. All centers transfused single-donor apheresis platelets; 20% allowed pathogen reduction (PR). The majority of centers have strategies limiting the amount of incompatible plasma transfused; however, few titrate ABO isoagglutinins in plasma-containing products (20% for platelets and 9.1% for plasma). CONCLUSIONS: Variability exists in BB practice for neonatal and pediatric transfusion. Future studies are needed to understand and define best BB practices in these patient populations.

Selecting COVID-19 convalescent plasma for neutralizing antibody potency using a high-capacity SARS-CoV-2 antibody assay.

BACKGROUND: Efficacy of COVID-19 convalescent plasma (CCP) is hypothesized to be associated with the concentration of neutralizing antibodies (nAb) to SARS-CoV-2. High capacity serologic assays detecting binding antibodies (bAb) have been developed; nAb assays are not adaptable to high-throughput testing. We sought to determine the effectiveness of using surrogate bAb signal-to-cutoff ratios (S/Co) in predicting nAb titers using a pseudovirus reporter viral particle neutralization (RVPN) assay. METHODS: CCP donor serum collected by three US blood collectors was tested with a bAb assay (Ortho Clinical Diagnostics VITROS Anti-SARS-CoV-2 Total, CoV2T) and a nAb RVPN assay. Prediction effectiveness of various CoV2T S/Co criteria was evaluated for RVPN nAb NT50 titers using receiver operating characteristics. RESULTS: Seven hundred and fifty-three CCPs were tested with median CoV2T S/Co and NT50 of 71.2 of 527.5. Proportions of donors with NT50 over target nAb titers were 86% ≥1:80, 76% ≥1:160, and 62% ≥1:320. Increasing CoV2T S/Co criterion reduced the sensitivity to predict NT50 titers, while specificity to identify those below increased. As target NT50 titers increase, the CoV2T assay becomes less accurate as a predictor with a decline in positive predictive value and rise in negative predictive value. CONCLUSION: Selection of a clinically effective nAb titer will impact availability of CCP. Product release with CoV2T assay S/Co criterion must balance the risk of releasing products below target nAb titers with the cost of false negatives. A two-step testing scheme may be optimal, with nAb testing on CoV2T samples with S/Cos below criterion.

Establishing Pediatric Reference Ranges for Rotational Thromboelastometry.

OBJECTIVES: The aim of our investigation was to establish normal pediatric reference intervals (PRIs) for rotational thromboelastometry (ROTEM) Delta assays in a representative group of healthy children, 0 to 18 years of age, at our institution. METHODS: This was a prospective study of healthy pediatric patients undergoing elective minor surgery requiring placement of an intravenous cannula. The sample size for patients was 20 per age group of either sex from 5 different age groups based on coagulation system maturity: 0 to 6 or fewer months, more than 6 to 12 or fewer months, more than 1 year to 5 or fewer years, more than 5 to 11 or fewer years, and more than 11 to 18 or fewer years. ROTEM Delta assays assessed include the EXTEM, INTEM, and FIBTEM. RESULTS: We defined 2 sets of ROTEM PRIs for our patient population: one for patients 11 years or younger and one for children more than 11 years of age. For those 11 years or younger, the PRIs were derived from the 2.5th and 97.5th percentiles from the 0 to 11 age groups. For those older than 11 years, previously published adult reference intervals validated internally with adult normal samples were used. CONCLUSIONS: The 2 sets of PRIs were embedded into our electronic medical record, allowing clinicians to easily interpret their patient's ROTEM results against age-verified reference ranges, enabling them to make informed transfusion decisions.