Allogeneic Donor Leukocytes Research Articles

Orphan designation: Adenovirus-specific T-cells derived from allogeneic donor leukocytes, expanded ex vivo, Treatment of adenovirus infection in allogeneic haematopoietic stem cell transplant recipients

Orphan designation: Adenovirus-specific T-cells derived from allogeneic donor leukocytes, expanded ex vivo, Treatment of adenovirus infection in allogeneic haematopoietic stem cell transplant recipients

Orphan designation: Adenovirus-specific T-cells derived from allogeneic donor leukocytes, expanded ex vivo, Treatment of adenovirus infection in allogeneic haematopoietic stem cell transplant recipients

Orphan designation: Adenovirus-specific T-cells derived from allogeneic donor leukocytes, expanded ex vivo, Treatment of adenovirus infection in allogeneic haematopoietic stem cell transplant recipients

Peculiarities of studying the effects of pathogen reduction technologies on platelets.

The transfusion of platelet concentrates (PCs) is mainly used for treatment of thrombocytopenic, trauma or surgery patients. The integrity and safety of these platelet preparations, however, is compromised by the presence of pathogens, such as viruses, bacteria and parasites. The transfer of allogeneic donor leukocytes contaminating PCs can also potentially cause adverse reactions in recipients. These considerations prompted the development and implementation of pathogen reduction technologies (PRT), which are based on chemically induced cross-linking and inactivation of nucleic acids. While the incumbent PRT may provide some protection against transfusion-transmitted infections, they are ineffective against infectious prions and may not inactivate other emerging pathogens. In addition, the safety of PRT concerning platelet viability and function has been questioned in several reports. Recent studies suggest that PRT, such as Intercept, may adversely affect the messenger RNA (mRNA) and microRNA content of platelets, as well as their functional integrity, which may compromise the clinical benefits of PRT. Here, we will discuss about the peculiarities of studying the effects of PRT on platelets, which will need to be taken into account in future studies aimed to characterize further, and polish, the rugged side of this otherwise useful and potentially important approach in transfusion medicine.

Use of leukodepletion filters for the removal of bacteria.

Recipient exposure to allogeneic donor leukocytes can mediate a number of immunologic complications of transfusion or can transmit leukotropic viruses carried by the donor. Leukocyte depletion of cellular blood components has been shown to reduce the incidence of such complications. In recent years, prestorage leukocyte depletion by filtration has also been suggested as a means of decreasing the incidence of bacterial overgrowth in cellular blood components. This review analyzes published studies on the use of leukodepletion filters for removal of Staphylococcus epidermidis and Yersinia enterocolitica from blood. Although ineffective for removal of S. epidermidis from Platelet Concentrates, inoculation studies demonstrate removal of low levels of Y. enterocolitica from Red Cell Concentrates. Based on these studies, four possible mechanism(s) for removal of bacteria by leukodepletion filters are analyzed: phagocytosis by leukocytes during a prefiltration holding period; complement-mediated bacterial killing enhanced by filtration; adherence of bacteria to leukocyte surfaces retained within the filter; and direct removal of bacteria by the filter media. Just as multiple mechanisms appear to account for the efficiency with which these filters deplete blood of leukocytes, it is likely that more than one mechanism accounts for the experimental observation that leukocyte depletion filters can reduce overgrowth of Y. enterocolitica in stored Red Cell Concentrates.

Effects on recipients of exposure to allogeneic donor leukocytes

Blood transfusion recipients are exposed to allogeneic donor leukocytes at the time of transfusion. Exposure to allogeneic donor leukocytes has been linked to a variety of complications of transfusion including primary HLA alloimmunization and platelet refractoriness, febrile nonhemolytic transfusion reactions, transmission of leukotropic viruses, transfusion-associated graft versus host disease, and transfusion-induced immune suppression. The development of high-performance leukodepletion blood filters and of low-leukocyte plateletapheresis machines has provided the technology to reduce recipient exposure to allogeneic donor leukocytes. This article provides a brief review of current information on the utility and shortcomings of these technologies for the prevention of leukocyte-mediated transfusion complications.