BACKGROUND Delayed, large‐volume bacterial culture and amotosalen/ultraviolet‐A light pathogen reduction are effective at reducing the risk of bacterial proliferation in platelet concentrates (PCs). Hemovigilance programs continue to receive reports of suspected septic transfusion reactions, most with low imputability. Here, we compile national hemovigilance data to determine the relative efficacy of these interventions. STUDY DESIGN AND METHODS Annual reports from the United Kingdom, France, Switzerland, and Belgium were reviewed between 2005 and 2016 to assess the risk of bacterial contamination and septic reactions. RESULTS Approximately 1.65 million delayed, large‐volume bacterial culture‐screened PCs in the United Kingdom and 2.3 million amotosalen/ultraviolet‐A–treated PCs worldwide were issued with no reported septic fatalities. One definite, one possible, and 12 undetermined/indeterminate septic reactions and eight contaminated “near misses” were reported with delayed, large‐volume bacterial cultures between 2011 and 2016, for a lower false‐negative culture rate than that in the previous 5 years (5.4 vs. 16.3 per million: odds ratio, 3.0; 95% confidence interval, 1.4‐6.5). Together, the Belgian, Swiss, and French hemovigilance programs documented zero probable or definite/certain septic reactions with 609,290 amotosalen/ultraviolet‐A–treated PCs (<1.6 per million). The rates were significantly lower than those reported with concurrently transfused, nonpathogen‐reduced PCs in Belgium (<4.4 vs. 35.6 per million: odds ratio, 8.1; 95% confidence interval,1.1‐353.3) and with historic septic reaction rates in Switzerland (<6.0 vs. 82.9 per million: odds ratio, 13.9; 95% confidence interval, 2.1‐589.2), and the rates tended to be lower than those from concurrently transfused, nonpathogen‐reduced PCs in France (<4.7 vs. 19.0 per million: odds ratio, 4.1; 95% confidence interval, 0.7‐164.3). CONCLUSION Pathogen reduction and bacterial culture both reduced the incidence of septic reactions, although under‐reporting and strict imputability criteria resulted in an underestimation of risk.

From the crop of the medicinal leech, Hirudo medicinalis, only Aeromonas veronii bv. sobria can be cultured consistently. Serum-sensitive A. veronii mutants were unable to colonize H. medicinalis, indicating the importance of the mammalian complement system for this unusual simplicity. Complementation of one selected mutant restored its ability to colonize. Serum-sensitive mutants are the first mutant class with a colonization defect for this symbiosis.Aeromonas veronii bv. sobria and Aeromonas hydrophila are pathogens of fish (20,26) and humans, causing wound infections, septicemia, and probably diarrhea (2-4, 10, 12). In addition to being a pathogen, A. veronii bv. sobria is the digestive tract symbiont of the medicinal leech, Hirudo medicinalis (6). The symbionts are housed in the crop of the digestive tract, apparently to the exclusion of other culturable bacteria (5, 6). The symbionts are thought to aid in the digestion of the ingested blood, provide essential nutrients to the host, or prevent other bacteria from colonizing (5). Interestingly, they can also infect the wounds of patients during medical application if the leeches are attached to tissue with poor blood circulation and the patients do not receive preemptive antibiotics (1,3,9,18).A recent study evaluated the ability of clinical Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus isolates to colonize the medicinal leech and discovered that the strains tested either could not proliferate inside the medicinal leech or were killed (9). The concentration of the E. coli strain decreased inside the medicinal leech for the first 48 h after feeding, suggesting that the bacteria were killed (9). Heating the blood or the addition of EDTA or EGTA and Mg 2ϩ to the blood prevented the killing of the E. coli strain in vitro (9). These treatments indicate that a heat-sensitive and divalentcation (possibly Ca 2ϩ )-requiring property was responsible for the demise of the E. coli strain. This is suggestive of the membrane attack complex of the complement system. Heat treatment of the blood prior to feeding allowed the E. coli strain to proliferate inside the medicinal leech, suggesting that the complement system was also responsible for inhibiting its growth inside the leech. These results indicate that powerful antimicrobial properties of mammals contribute to the unusual specificity of this bacterium-invertebrate symbiosis.If the complement system contributes to the specificity of this symbiotic interaction, then A. veronii bv. sobria mutants that have an increased sensitivity to the complement system would be expected to have a reduced ability to colonize the medicinal leech. Several surface structures are responsible for the resistance of bacteria to complement-mediated killing, including lipopolysaccharide (LPS), outer membrane proteins, polysaccharide capsule, and S layer (15,22,24). A previous study generated serum-sensitive mutants derived from the A. veronii bv. sobria strain AH-1 (also called TF7), which is of the O11 serotype and produc...

Key Points Clinically relevant imetelstat concentrations significantly inhibit CFU-MEG formation from MNCs of ET patients and reduce hTERT expression. However, similar concentrations of imetelstat do not inhibit cytokine-induced CFU-MEG from MNCs of healthy donors.

The Hereditary TTP Registry is an international cohort study for patients with a confirmed or suspected diagnosis of hereditary thrombotic thrombocytopenic purpura (hTTP) and their family members. Hereditary TTP is an ultra-rare blood disorder (prevalence of ∼1–2 cases per million), the result of autosomal-recessively inherited congenital ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) deficiency (ADAMTS13 activity <10% of the normal), and associated with yet many unanswered questions. Until December 2017, the Hereditary TTP Registry had enrolled 123 confirmed hTTP patients. Their median age at disease onset was 4.5 years (range: 0–70) and at clinical diagnosis 16.7 years (range: 0–69), a difference that highlights the existing awareness gap in recognizing hTTP. The systematic collection of clinical data of individual patients revealed their substantial baseline comorbidities, as a consequence of recurring TTP episodes in the past. Most notable was the high proportion of patients having suffered from premature arterial thrombotic events, mainly transient ischemic attacks, ischemic strokes, and to a lesser extent myocardial infarctions. At 40 to 50 years of age and above, more than 50% of patients had suffered from at least one such event, and many had experienced arterial thrombotic events despite regular plasma infusions every 2 to 3 weeks that supplements the missing plasma ADAMTS13. The article by van Dorland et al. (Haematologica 2019;104(10):2107–2115) and the ongoing Hereditary TTP Registry cohort study were recognized with the Günter Landbeck Excellence Award at the 50th Hemophilia Symposium in Hamburg in November 2019, the reason to present the Hereditary TTP Registry in more detail here.

Background: Holley (Hy) is a high-incidence antigen of the Dombrock blood group system (ISBT 014), present in almost 100% of most populations and more than 99% of Blacks. Since anti-Hy is an extremely rare antibody, data on its clinical relevance and in particular on a possible hemolytic disease of the fetus and newborn (HDFN) are scarce. Case Report: The pregnant patient underwent two autologous whole blood collections at weeks 17 and 19 of gestation with cryopreservation. In our case autologous whole blood collection was well tolerated. There were no signs of HDFN in the healthy newborn. Conclusion: Our case improves our understanding of anti-Hy alloantibodies during pregnancy. Additionally, autologous whole blood collection of RBC units with cryopreservation is a safe and feasible way to manage pregnancies in women with rare alloantibodies, when no compatible donor can be found.