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Polycythaemia vera is one of several classical myeloproliferative neoplasms that may occur in a juvenile onset or late‐onset adult forms. It is linked to specific genetic mutations that cause a deleterious elevation in the patient's red cell mass. The discourse on genetics includes an exposé on the molecular biology of the disease and how a shared JAK2 V617F mutation can co‐exist among three distinct neoplasms. Concepts of genetics and immunology help define the origin and behaviour of the disease: the tracking of allele burdens of mutations (genetic dosage), the timing or order of acquired mutations, the import of bystander mutations and the onco‐inflammatory response; all theories are invoked to explain the progression of disease severity and potential transformational leukaemia. The World Health Organization's diagnostic criteria are accessed to focus on the subtleties of the Hb laboratories and sifting through the challenging listing of differential diagnoses that mimic PV, and our report includes an overview of manual and automated phlebotomy (erythrocytapheresis) procedures, enumerating their clinical indications, significance of temporary phlebotomy resistance and optimizing safety/ efficacy, quality and cost. Stratification of low and high‐risk disease distinguishes when to commence chemo‐cytoreductive therapy in the high‐risk patient to prevent thrombotic complications. Drug resistance is circumvented by artfully switching drugs or using novel drug designs. [ABSTRACT FROM AUTHOR]

Reflection on passive immunotherapy in those who need most: some novel strategic arguments for obtaining safer therapeutic plasma or autologous antibodies from recovered COVID-19 infected patients The COVID-19 pandemic is an emerging new human disease, for which no vaccines, or monoclonal antibodies (mAbs) or drugs, are currently available for therapy. In fact, critically ill COVID-19 patients as well as those in early phases of the disease might be excellent candidates for passive immunotherapy, and for further randomized clinical trials for addressing its clinical usefulness in various patient subcategories. [Extracted from the article]

BACKGROUND: Universal leukodepletion (LD) has been implemented in the United Kingdom to reduce the risk of transfusion-transmitted variant Creutzfeldt-Jakob disease. If LD causes microvesiculation of blood cells, however, potentially infectious membrane-associated prion could reach the final products. STUDY DESIGN AND METHODS: We have measured microvesicles (MV) derived from red cells (RBC-MV), platelets (PLT-MV), and white blood cells (WBC-MV) and cellular prion protein (PrPc) in blood components produced by four whole-blood, five RBC, three PLT, and two plasma LD filters and three plateletpheresis techniques. RESULTS: RBC-MV and PLT-MV were either unaltered or reduced by all processes, with PLT-MV reduced 10-fold by RBC LD and greater than 300-fold by plasma LD. WBC-MV were reduced or unchanged by RBC and PLT LD and reduced by plasma LD. Whole-blood filtration appeared to increase MVs derived from granulocytes, but the load in the final components was comparable to that in processed RBCs in additive solution. PrPc was reduced by whole-blood, RBC, and plasma LD and unchanged by PLT techniques. There were differences between various filters and techniques, which were generally minor compared to the overall effects. CONCLUSION: These findings suggest no detrimental effects of LD processes in terms of generation of MVs or PrPc release. [ABSTRACT FROM AUTHOR]

Background: Sickle cell trait donations can block leukodepletion (LD) filters or fail to LD, but the variables affecting blockage are unclear.Study Design and Methods: To identify critical variables for further study, the relationship was investigated between filter blockage and donor characteristics, processing conditions, PLT and coagulation system activation, and microvesicle formation in donations with (n = 63) and without (n = 40) sickle trait. With eight filter types whole blood was LD either at ambient temperature on Day 0 or after overnight 4 degrees C hold. Markers of PLT activation (CD62P and CD63 expression and soluble CD62P) and coagulation activation (activated FXII and prothrombin fragment 1 + 2 [F1 + 2]), RBC microvesicles, blood gases, and residual WBCs were measured.Results: All Day 0 filtrations blocked (n = 7). On Day 1, no filter tested was 100 percent successful, with most achieving an approximate 50 percent success rate. Two filters blocked consistently and an additional filter did not block, but resulted in 50 percent of units with high residual WBC counts (30 x 10(6)-394 x 10(6)/unit). Day 1 filtration was not improved if performed at 4 degrees C. Donor RBC variables and prefiltration measures varied little between blocked and successful filtrations except pO2, where 9 of 17 blockages had a pO2 of less than 5.0 kPa, compared with 0 of 13 completed filtrations. F1 + 2 levels increased after filtration in sickle trait units, a consequence of slow flow rate.Conclusion: Filter blockage in sickle trait donors cannot be predicted by donor characteristics or filter type and is not related to PLT or coagulation activation, but can be reduced by storing units at 4 degrees C before filtration. [ABSTRACT FROM AUTHOR]

Sickle cell trait donations can block leukodepletion (LD) filters or fail to LD, but the variables affecting blockage are unclear. To identify critical variables for further study, the relationship was investigated between filter blockage and donor characteristics, processing conditions, PLT and coagulation system activation, and microvesicle formation in donations with (n = 63) and without (n = 40) sickle trait. With eight filter types whole blood was LD either at ambient temperature on Day 0 or after overnight 4°C hold. Markers of PLT activation (CD62P and CD63 expression and soluble CD62P) and coagulation activation (activated FXII and prothrombin fragment 1 + 2 [F1 + 2]), RBC microvesicles, blood gases, and residual WBCs were measured. All Day 0 filtrations blocked (n = 7). On Day 1, no filter tested was 100 percent successful, with most achieving an approximate 50 percent success rate. Two filters blocked consistently and an additional filter did not block, but resulted in 50 percent of units with high residual WBC counts (30 × 106-394 × 106/unit). Day 1 filtration was not improved if performed at 4°C. Donor RBC variables and prefiltration measures varied little between blocked and successful filtrations except pO2, where 9 of 17 blockages had a pO2 of less than 5.0 kPa, compared with 0 of 13 completed filtrations. F1 + 2 levels increased after filtration in sickle trait units, a consequence of slow flow rate. Filter blockage in sickle trait donors cannot be predicted by donor characteristics or filter type and is not related to PLT or coagulation activation, but can be reduced by storing units at 4°C before filtration. [ABSTRACT FROM AUTHOR]