Laura Cooling

Blood Groups in Infection and Host Susceptibility

SUMMARY Blood group antigens represent polymorphic traits inherited among individuals and populations. At present, there are 34 recognized human blood groups and hundreds of individual blood group antigens and alleles. Differences in blood group antigen expression can increase or decrease host susceptibility to many infections. Blood groups can play a direct role in infection by serving as receptors and/or coreceptors for microorganisms, parasites, and viruses. In addition, many blood group antigens facilitate intracellular uptake, signal transduction, or adhesion through the organization of membrane microdomains. Several blood groups can modify the innate immune response to infection. Several distinct phenotypes associated with increased host resistance to malaria are overrepresented in populations living in areas where malaria is endemic, as a result of evolutionary pressures. Microorganisms can also stimulate antibodies against blood group antigens, including ABO, T, and Kell. Finally, there is a symbiotic relationship between blood group expression and maturation of the gastrointestinal microbiome.

Anti-A and anti-B titers in pooled group O platelets are comparable to apheresis platelets.

BACKGROUND: Although uncommon, acute hemolytic transfusion reactions (AHTRs) have been reported after transfusion of group O single‐donor apheresis platelets (SDPs) to group A, B, and AB recipients. Current methods for identifying “high‐titer” SDPs include tube and gel methods. The risk of a high‐titer unit is considered low with group O, poststorage, pooled platelet concentrates (PPLTs); however, data regarding anti‐A and anti‐B titers in PPLTs are lacking.

A prospective randomized trial of two popular mononuclear cell collection sets for autologous peripheral blood stem cell collection in multiple myeloma

BACKGROUND: The COBE Spectra AutoPBSC collection set (AUTO‐kit; CaridianBCT) is a popular dual‐stage collection set for peripheral blood progenitor (PBPC) collection. Although the AUTO‐kit is purportedly equivalent to the white blood cell (WBC) collection set (WBC‐kit) for PBPC collection, improved CD34 yields after switching from the AUTO‐kit to the WBC‐kit were anecdotally observed, particularly in patients with higher WBC counts. A prospective, randomized trial of the AUTO‐ and WBC‐kits for PBPC collection in multiple myeloma (MM) patients was therefore designed.

An In Vitro Model of Fabry Disease

Fabry disease is an X-linked inherited loss of alpha-galactosidase A (alpha-Gal A). Affected patients experience complications that include neuropathy, renal failure, and cardiovascular disease. Although the genetic and biochemical basis of this sphingolipidosis is well studied, the basis for the vascular disease remains poorly understood. In an attempt to create a suitable in vitro model of this disease, conditions for the growth of primary cultures of aortic endothelial cells from wild-type and alpha-Gal A -/0 mice were established. The cultured cells demonstrated CD-31 expression by flow cytometry and LDL binding by immunofluorescence. The glycolipid expression patterns were compared between wild-type and alpha-Gal A null cells. Importantly, cells from alpha-Gal A -/0 mice but not alpha-Gal A +/0 mice expressed high levels of the globo-series glycosphingolipid globotriaosylceramide (Gb3). The age-dependent elevation in Gb3 was measured. By 4 mo of age, alpha-Gal A -/0 mouse aortic endothelial cells achieved their peak Gb3 levels. The ability to lower Gb3 levels pharmacologically was assessed next. The glucosylceramide synthase inhibitor ethylenedioxyphenyl-P4 significantly lowered but did not eliminate Gb3 levels by 96 h of treatment. Gb3 synthesis was completely blocked as measured by [14C]galactose labeling. Recombinant alpha-Gal A more significantly lowered Gb3 levels by 48 h but had a more limited effect on de novo synthesis. Together, both agents eliminated detectable Gb3. In summary, primary cultures of aortic endothelial cells from Fabry mice retain the phenotype of elevated globo-series glycosphingolipids. These cells provide a useful model for comparing pharmacologic agents used for glycolipid reduction.

Safety of leukoreduced, cytomegalovirus (CMV)-untested components in CMV-negative allogeneic human progenitor cell transplant recipients

Transfusion-transmitted cytomegalovirus (TT-CMV) infection can lead to significant morbidity and mortality in CMV-negative (CMV-N) hematopoietic progenitor cell (HPC) transplant patients. In 1995, Bowden and colleagues demonstrated the efficacy of leukoreduced components to reduce TT-CMV in most high-risk populations, although there remained safety concerns in CMV-N allogeneic HPC transplant recipients. As a result, several transplant programs recommended both leukoreduced and CMV-N components for CMV-N allogeneic HPC patients receiving transplants from CMV-N donors (CMV). A more recent study, however, has challenged the clinical benefit of requiring CMV-N, in addition to leukoreduction, in CMV HPC patients. In a 10-year study, Thiele and colleagues found no cases of TT-CMV in 23 CMV HPC patients transfused with 1847 CMVuntested (CMV-U), leukoreduced components. We would like to share our institution’s experience in 100 CMV allogeneic HPC patients transfused with 6465 CMV-N and CMV-U cellular components. Before July 2006, the University of Michigan provided, when available, CMV-N components to all CMV HPC transplant recipients. A preliminary 12-month retrospective review showed that 52% (14/27, 2004) had received leukoreduced, CMV-U blood components due to shortages in CMV-N products, with no cases of TT-CMV. As a result, the transfusion policy was changed in mid-2006 to provide leukoreduced, CMV-U products for all HPC patients, regardless of pretransplant CMV status. For quality assurance, we monitored the CMV conversion rate over a 36-month period (January 2005 to December 2007) covering an 18-month period before and after the change in transfusion policy (Table 1). Per institutional practice, CMV-N patients were screened for CMV IgG every 1 to 2 months pretransplant, followed by regular testing for CMV nucleic acid testing (NAT) after transplant. The minimum posttransplant follow-up was 12 months. All blood products were provided by Southeast Michigan American Red Cross (Detroit, MI) and were leukoreduced after storage (Leukotrap RC system, Pall Corp., Port Washington, CA). As shown in Table 1, 100 patients were available for analysis and included both adult and pediatric patients. All patients were CMV-N before transplant, received a CMV allogeneic HPC transplant, and underwent weekly posttransplant CMV NAT monitoring. Except for sex, there were no significant differences in patient demographics, transplant type, or transfusion support in the two study cohorts. In the CMV-N policy period, only 11% to 15% of cellular components were CMV-N, with most patients receiving a mix of CMV-N and CMV-U. Only five patients received 100% CMV-N products. All five patients had low transfusion needs, requiring 2 to 10 red blood cell (RBC) and two to three platelet (PLT) transfusions. Two adult male patients had a single positive test for CMV IgG at 3 and 5 weeks after transplant, respectively (Table 1). Both patients tested negative for CMV IgM and CMV NAT and had no evidence of clinical CMV infection. Each patient received between 42 and 45 CMV-U cellular components in the weeks before seroconversion: neither patient had received intravenous immune globulin before CMV IgG testing. There were no CMV seroconversions in the CMV-U period. The overall CMV IgG seroconversion rate was 2% per patient and 0.03% per unit, which is comparable to the findings by Bowden and coworkers (2.4% per patient, 0.023% per component). The rate of confirmed TT-CMV was 0%, consistent with the study by Thiele and coworkers and lower than that reported by Wu and coworkers (6.5% per patient, 0.23% per CMV-positive component). As discussed by Thiele and Wu, the CMV IgG detected in our patients likely represents passive antibody from recent transfusions. Our findings confirm those of Thiele and affirm the equivalent safety of CMV-U, leukoreduced components in CMV allogeneic HPC patients. The absence of clinical TT-CMV infection in our study and that by Thiele and coworkers, despite the combined transfusion of nearly 8000 CMV-U, leukoreduced components, contradicts sentiments from a past multivariate analysis, which advocated continued provision of CMV-N and leukoreduced components for CMV transplant patients. The improved safety of CMV-N over CMV-U, leukoreduced is also not supported by a recent large prospective study of 34,000 blood donors. Ziemann and colleagues found CMV viremia only among newly seroconverted donors and a few CMV-N donors, arguing that CMV-N components may present the higher risk of TT-CMV due to passive transfusion of free CMV DNA. In summary, policies stipulating leukoreduced, CMV-N components in CMV allogeneic HPC patients do not confer additional safety and are limited by product shortages and significant transfusion support required by many allogeneic HPC patients.

National Institutes of Health State of the Science Symposium in Therapeutic Apheresis: Scientific Opportunities in Extracorporeal Photopheresis

The clinical use of extracorporeal photopheresis (ECP) for accepted indications such as graft-versus-host disease, transplant rejection, and cutaneous T-cell lymphoma continues to increase. Expanded applications for ECP, such as the treatment of select autoimmune diseases, are being explored. Extracorporeal photopheresiss capacity to both immunotolerize in the autoreactive setting, while immunizing against a lymphoma is unusual and suggestive of a unique mechanism. It is likely that ECPs induction of dendritic cells is key to its efficacy in both of these settings, but exactly how ECP impacts other immune components and their interactions is not fully understood. Further basic science research is necessary to elucidate how these dissimilar cellular activities are functionally integrated. On the clinical side, collaborative multicenter trials designed to recognize the principal variables controlling therapeutic responses and improve prognostic indicators may enable tailoring devices, treatment schedules, and doses to the needs of the individual patients or diseases. This review describes our current understanding of how ECP influences the immune system, reviews the existing clinical applications of ECP, and explores areas for future basic science and clinical research as presented at the National Institutes of Health State of the Science Symposium in Therapeutic Apheresis in November 2012.

How do I allocate blood products at the end of life? An ethical analysis with suggested guidelines.

Blood products are scarce resources requiring prudent and reasoned allocation. The utilization of red blood cells and platelets in terminally ill patients can be complicated and requires guidelines tempered by individualized considerations. Representative cases are discussed in which blood products are requested or utilized by patients at the end of life. Relevant literature is reviewed and ethical issues pertaining to each case are discussed. A practical approach to blood product utilization at the end of life is suggested.

Successful treatment of refractory immune hemolysis following unrelated cord blood transplant with campath-1H

Immune‐mediated hemolytic anemia is a well‐recognized complication of hematopoietic stem cell transplantation. We report on a 6‐year‐old boy with X‐linked adrenoleukodystrophy who developed severe delayed alloimmune hemolytic anemia associated with immune‐mediated neutropenia and thrombocytopenia following major ABO incompatible unrelated cord blood transplantation. The patients cytopenias were refractory to treatment with corticosteroids, cyclosporine, intravenous immune globulin, rituximab, and pentostatin. After one course of Campath‐1H his hematologic parameters normalized, suggesting that the compound may be an effective therapy for complex immunohematologic disorders complicating hematopoietic stem cell transplantation. The case also emphasizes the importance of T‐cells in transplant associated immune cytopenias. Pediatr Blood Cancer 2008;50:917–919.

Human platelets express gangliosides with LKE activity and ABH blood group activity.

BACKGROUND: Platelets express several neutral glycosphingolipids with ABH and P blood group activity that may play a role in infectious, autoimmune, and alloimmune thrombocytopenia. In RBCs, sialylated glycosphingolipids or gangliosides with blood group activity have also been reported. To determine whether similar antigens are expressed by platelets, the total platelet ganglioside fraction was isolated and screened for blood‐group‐active glycosphingolipids.

Inverse expression of Pk and Luke blood group antigens on human RBCs

BACKGROUND: Luke (LKE) is a high‐frequency RBC antigen, related to the P blood group system. A LKE‐negative phenotype is found in 1 to 2 percent of donors and may be associated with increased Pk. Because Pk and similar glycolipids are receptors for shiga toxin on cell membranes, a LKE‐negative phenotype could have implications for infections by Shigella dysenteriae and enterohemorrhagic Escherichia coli.