Jeanne Salata

Pathogen inactivation of Leishmania donovani infantum in plasma and platelet concentrates using riboflavin and ultraviolet light

Background and Objectives  Leishmania is transmitted by the bite of the phlebotomine sandfly or by transfusion of infected blood products. Leishmaniasis currently poses a significant problem in several parts of the world, and is an emerging problem in others. The Mirasol PRT technology is based on the use of riboflavin and ultraviolet light to generate chemical reactions in the nucleic acids of pathogens, which prevents replication and leads to inactivation. The intent of this study was to examine the ability of the Mirasol PRT System to kill the Leishmania parasite in human plasma and platelet concentrates.

Neutrophil priming, caused by cell membranes and microvesicles in packed red blood cell units, is abrogated by leukocyte depletion at collection

UNLABELLED BACKGROUND AND OBJECTS: Lipids with platelet activating factor (PAF)-like activity in supernatant of packed red blood cells (PRBC) cause priming of the neutrophil respiratory burst. This effect increases with length of storage. Washing of PRBC has been considered as a means to eliminate this effect; however, the role of the cellular component was not evaluated independently of the supernatant. The source of the inflammatory lipids of the supernatant is likely to be cell membranes altered during ageing in storage and therefore, washing will not eliminate neutrophil priming caused by transfusion of aged PRBC units. The ability of washed PRBC to prime mononuclear cells for another known effect of PAF, the production of IL-8, and the probability that this lipid activity is present on microparticles in PRBC supernatant were also investigated. MATERIALS AND METHODS At collection 10 units of whole blood were split into two equal aliquots one filtered and one unfiltered. PRBC were prepared and stored at 4 degrees C in CPD-AS5. Each week, fresh neutrophils were incubated with samples of washed PRBC and fixed. Change in CD11b, a marker known to increase on the surface of primed neutrophils, was determined by flow cytometry. To determine whether neutrophil priming ability of PRBC supernatant is contained on microvesicles, centrifuged and uncentrifuged supernatant samples were incubated with fresh neutrophils and change in CD11b expression was determined. Plasma IL-8 levels were also measured after exposure of monocytes from fresh whole blood to filtered and unfiltered washed PRBC with and without the addition of fMLP. RESULTS Washed PRBC caused a 50-116% increase in CD11b neutrophil surface expression over baseline expression. Filtration of whole blood at collection reduced this CD11b up-regulation by 25-34%. Reduction of priming ability by filtration began on the day of collection and persisted for the storage life of the units. Centrifugation resulted in a reduction of CD11b up-regulation of 11-28% compared with unspun supernatant. Incubation of unfiltered PRBC resulted in priming of mononuclear leukocytes for IL-8 production with a 73-109% increase over baseline, but no increase over baseline was seen for incubation with filtered blood. CONCLUSION Washing does not eliminate the ability of PRBC units to prime neutrophils and mononuclear cells, because the cellular component of PRBC, in addition to the supernatant, induces priming. Leukodepletion filters significantly reduce these effects compared with unfiltered PRBC. The in vitro beneficial effect of filtration lasts for the shelf life of 42 day units. The ability of PRBC supernatant to prime neutrophils is present on microvesicles.

Inactivation of Orientia tsutsugamushi in red blood cells, plasma, and platelets with riboflavin and light, as demonstrated in an animal model

BACKGROUND: Treatment of blood products with riboflavin and light has been used to reduce the number of certain pathogens. Orientia (formerly Rickettsia) tsutsugamushi, the scrub typhus agent, is an obligate intracellular bacterium that grows free in the cytoplasm of infected cells. This study evaluated the capability of riboflavin and light to inactivate O. tsutsugamushi in red blood cells (RBCs), platelets (PLTs), and plasma, as measured by mouse infectivity.

Leukodepletion filters reduce Leishmania in blood products when used at collection or at the bedside

BACKGROUND:  Leishmania is an intracellular parasite of monocytes transmissible by transfusion. The feasibility of reducing Leishmania with leukodepletion filters was studied. At collection, infected blood contains the amastigote form of Leishmania within monocytes. Amastigotes cause the rupture of monocytes releasing free amastigotes that convert to promastigotes, which exist extracellularly at blood storage temperatures. Leukodepletion filters were tested at various time points in this process.

Photoinactivation of Leishmania donovani infantum in red cell suspensions by a flexible thiopyrylium sensitizer

Background and Objectives  Leishmaniasis is a disease caused by protozoan parasites of the genus Leishmania, which are intracellular parasites of monocytes and macrophages. Transmission of the organism has been observed by transfusion of infected blood from asymptomatic donors to immunocompromised recipients, leading to clinically apparent disease. There is no licensed Leishmania screening test currently available.

Removal of Plasmodium falciparum–infected red blood cells from whole blood by leukoreduction filters

BACKGROUND: There has been an unexplained decrease in the incidence of transfusion‐transmitted malaria in recent years. The decrease in incidence has paralleled the increasing use of leukoreduction filters. Malaria‐infected red blood cells (RBCs) share surface characteristics of hemoglobin S–containing cells. Because units collected from donors with sickle trait do not filter optimally due to adherence of RBCs to the filters, the possibility that malaria‐infected RBCs may also adhere to filters was investigated.

Inactivation of Leishmania donovani infantum and Trypanosoma cruzi in red cell suspensions with thiazole orange

BACKGROUND: Methods for pathogen inactivation are currently available in some European countries for treatment of plasma and platelet (PLT) components; no approved method for treatment of red cells (RBCs) or whole blood is ready for implementation. In a previous study, thiazole orange (TO), a dye commonly used to count reticulated RBCs and PLTs, exhibited potent photoactivity against human immunodeficiency virus‐1 and several model viruses in RBC suspensions. The aim of this study is to further evaluate the ability of TO to inactivate pathogens by measuring its activity against the protozoa Leishmania donovani infantum and Trypanosoma cruzi.

White particulate matter found in blood collection bags consist of platelets and leukocytes

BACKGROUND:  In late January 2003, some blood centers and hospitals throughout the US voluntarily sus‐pended the use of some RBC and plasma units for trans‐fusion due to the presence of unknown white particulate matter (WPM) in these units. To better understand the WPM phenomena, a number of technologies were used to establish the nature of the particulates observed in Terumo Collection sets.

In vitro variables of red blood cell components collected by apheresis and frozen 6 and 14 days after collection

BACKGROUND:  An automated cell processing system (ACP 215, Haemonetics Corp.) can be used for the glycerolization and deglycerolization of RBC components, but the components must be 6 or fewer days old. Depending on the anticoagulant (CP2D)/additive solution (AS) used, deglycerolized RBCs can be stored at 1 to 6°C for up to 14 days. This study evaluated in vitro variables of apheresis RBC stored for 6 and 14 days at 1 to 6°C before glycerolization and 14 days after deglycerolization.