The King is Dead, Long Live the King: Entering A New Era of Stem Cell Research and Clinical Development

With the approval of the first therapeutic cancer vaccines for veterinarian and human use, the field reached a significant milestone after a considerable interval of tumultuous research and development marked by numerous ups and downs. As the mechanism of action and clinical benefit afforded by this class of agents are starkly different from that of conventional or small targeted therapies for cancer, there are still numerous hurdles that need to be overcome to fully unleash their potential. These challenges and efforts are illustrated in a book just published on this subject, a non-exhaustive yet representative synopsis of the latest advances in cancer vaccine technologies in various stages of development. Major lessons resulting from clinical testing of cancer vaccines and other immune interventions, are being integrated in novel, cutting edge platform technologies that blur the distinction between passive and active immunotherapies as well as carry the promise of fundamentally changing and improving the management of patients with cancer.     

Nylon-fiber-induced neutrophil fragmentation

We have investigated the effects of mechanical elution of neutrophils from nylon-wool fiber (NWF) using the scanning electron microscope and biochemical analysis of elution fractions. We have determined that mechanical removal of neutrophils from nylon-wool fiber disrupts neutrophils adherent to nylon-wool fiber and augments release of granules, release of peripheral cytoplasmic fragments, and release of lactic dehydrogenase, a soluble cytoplasmic enzyme. Mechanical shearing of the adherent cell, and not adherence per se, causes the fragmentation. The extent of fragmentation is proportional to the NWF surface area available to neutrophils and is maximal at the temperature for optimal adherence and spreading. Agents that decrease cell spreading (n-ethylmaleimide and cold) diminish fragmentation. Cytochalasin B, an agent that destabilizes the neutrophil cortex, increases fragmentation. Fragmentation may be an important contributing cause of the abnormal morphology, function, and in vivo survival of nylon-wool-fiber procured human neutrophils. The prevention of fragmentation would appear to be necessary to insure the procurement of optimally functioning cells. Elution of NWF-adherent neutrophils in the cold might be a practical way to diminish neutrophil damage during clinical filtration leukapheresis.     

Patient-specific transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is one of the leading causes of transfusion-associated mortality. The inadvertent transfusion of neutrophil antibodies can cause pulmonary transfusion reactions and TRALI. However, not all patients transfused with neutrophil antibodies experience transfusion reactions. A 22-year-old man with severe aplastic anaemia (SAA) experienced TRALI after a platelet transfusion. The donor was found to be alloimmunized to human neutrophil antigen (HNA)-3a, an antigen expressed by neutrophils from approximately 90% of Caucasians. Eleven other platelet components from this donor were transfused prior to this event and two caused reactions: one chills and one TRALI. Both episodes of TRALI occurred in the same male patient with SAA. The fact that one patient experienced TRALI following both exposures to anti-HNA-3a from the same donor whereas nine other recipients did not adds evidence to the observation that patient factors make a significant contribution to neutrophil antibody-mediated transfusion reactions.     

Alloimmunization to platelets in heavily transfused patients with sickle cell disease

Bone marrow transplantation (BMT) is now an option for some patients with sickle cell disease (SCD). Many SCD patients are multiply transfused with red blood cells (RBCs), and may be immunized to alloantigens other than erythrocyte antigens. Because platelet refractoriness is a significant complication during BMT, we wished to determine the prevalence of alloimmunization to platelets in transfused SCD patients. Sera collected from 47 transfused and 14 untransfused SCD patients were screened for HLA and platelet-specific antibodies. Transfusion and RBC antibody histories were reviewed. A subset of the patients were rescreened 1 year later. Eighty-five percent of patients with at least 50 RBC transfusions (22 of 26), 48% of patients with less than 50 transfusions (10 of 21), and none of 14 untransfused patients demonstrated platelet alloimmunization (P < .05). Platelet alloimmunization was more prevalent than RBC alloimmunization (20% to 30%). Half of the platelet reactivity was chloroquine-elutable. Eighteen of 22 patients (82%) on chronic RBC transfusion remained platelet-alloimmunized 11 to 22 months after initial testing. In summary, 85% of heavily transfused SCD patients are alloimmunized to HLA and/or platelet-specific antigens. These patients may be refractory to platelet transfusion, a condition that would increase their risk during BMT. Leukodepletion in the transfusion support of SCD patients should be considered to prevent platelet alloimmunization.     

Neutrophil and platelet antibodies in autoimmune lymphoproliferative syndrome

BACKGROUND AND OBJECTIVES: Autoimmune lymphoproliferative syndrome (ALPS), is an inherited disorder characterized by defective lymphocyte apoptosis, lymphadenopathy, splenomegaly, accumulation of T-cell receptor (TCR)-alphabeta+ CD4- CD8- T cells (double-negative T cells) and autoimmunity. We investigated the incidence and nature of neutrophil and platelet antibodies in patients with ALPS. MATERIALS AND METHODS: Sera from 26 patients with ALPS were tested for neutrophil antibodies by granulocyte immunofluorescence, granulocyte agglutination and monoclonal antibody immobilization assays of granulocyte antigens, and for platelet antibodies using a solid-phase antibody-detection system. RESULTS: Neutrophil antibodies were detected in 46% of patients with ALPS. Antibody specificity could be defined in eight of the 12 patients with neutrophil antibodies. Among these eight patients, four had antibodies directed against more than one antigen. Overall, 14 antibodies directed to specific antigens were identified: three were directed to the HNA-1a antigen of FcgammaRIIIb; two to the HNA-1b antigen of Fcgamma-RIIIb; two to epitopes common to all FcgammaRIIIb molecules; four to the HNA-2a antigen of the NB1 glycoprotein; and three to neutrophil beta2 integrins. Platelet antibodies were detected in 35% of patients with ALPS. No antibody specificities were identified among the platelet antibodies. There was no association between the detection of neutrophil antibodies and a history of clinical neutropenia, or between the detection of platelet antibodies and a history of clinical thromobocytopenia. CONCLUSIONS: Neutrophil and platelet antibodies are important markers of ALPS, but do not always cause clinical cytopenias. The specificities of neutrophil antibody were similar to those found in children with autoimmune neutropenia but without ALPS.