Background: A 2-year-old, 10.8 kg male pediatric patient with X-linked chronic granulomatous disease (CGD) with McLeod syndrome (MLS) was scheduled for a hematopoietic stem cell transplant (HSCT). Identification of allogenic red blood cells (RBC) for post-transplant support was unsuccessful prompting the development of a customized method to collect and freeze rare autologous pediatric cells. Study Design and Methods: A protocol was developed for the collection of small volume pediatric whole blood (WB) via peripheral venipuncture with collection into 10 ml syringes containing anticoagulants. Additionally, a closed system RBC glycerolization and deglycerolization instrument was adapted to process small volume, non-leukoreduced WB. Both collection and WB processes were validated. In total 4 approximately 100 ml autologous units were collected and frozen. Two units were thawed, deglycerolized, and used for clinical transfusion support. To appreciate processing impacts on RBC rigidity, ektacytometry was performed on pre-processed and post-deglycerolization samples. Results: Free hemoglobin (HGB) of validation units after thawing/deglycerolization was <150 mg/dL with an average red cell recovery of 85%. These units also showed little difference between pre-and post-processing Lorrca deformability curves or membrane rigidity. Two pediatric units were thawed and deglycerolized for transfusion. Free HGB was 70 mg/dL and 50 mg/dL post-thaw, and these RBCs had a slight decrease in deformability and increased membrane rigidity.Discussion: Customized WB collection, glycerolization, freezing, and deglycerolization processes were developed to successfully support a pediatric patient with CGD and MLS after autologous HSCT. Both pediatric units Abbreviations: AABB, association for the advancement of blood and biotherapies; ACP-215, automated cell processor-215;

Introduction: Peripheral blood stem cell collection (PBSCC) is welldocumented in adults and pediatric patients with larger total blood volume (TBV). However, very little data are available for the successful PBSCC of pediatric patients weighing less than 10 kg. Here, we highlight our institutional approach to PBSCC in this smaller-sized patient population.Methods: Our protocol, including blood prime, was reviewed for PBSCC for bone marrow transplantation (BMT) in 18 children weighing 4.5-9.9 kg who safely underwent 37 PBSCC procedures at a single institution, Children's Hospital Colorado, between September 2016 and February 2022. Results: We attained the individualized collection goals in all 18 patients with an average yield of 17.03 million CD34+ cells/kg of patient body weight (range: 0.84-67.45 million/kg). The average collection efficiency of the procedures was 41.5% (range: 23.0%-71.5%). We performed all 37 procedures safely and without complication. The estimated average TBV was 587 mL (range: 351-765 mL), the average blood volume processed was 596 mL (range: 351-756 mL), and the average TBVs processed was 2.5 (range: 1-4). Conclusion: PBSCC in patients ranging from 4.5 to 9.9 kg is safe and effective for collecting peripheral blood stem cells for BMT.

Anti‐glomerular basement membrane (GBM) disease is a rarely described entity in the pediatric population, especially in those less than 3 years old. Even rarer, is double seropositive disease, consisting of anti‐GBM antibody plus anti‐neutrophil cytoplasmic antibodies. Both single and double antibody positive diseases are characterized by rapidly progressive glomerulonephritis, often without pulmonary involvement in the pediatric population. We report the case of a 2‐year‐old child with double seropositive anti‐GBM disease, the youngest in the current literature, along with the role of therapeutic plasma exchange and rituximab in disease treatment.