White cell apoptosis in platelet concentrates.

BACKGROUND: The aim of the present study was the evaluation of the apoptosis in residual white cells (WBCs) contained in platelet concentrates (PCs) and of the relationship of this apoptosis with the concentration of inflammatory cytokines in the medium and with platelet activation. STUDY DESIGN AND METHODS: Three independent methods were used to evaluated apoptosis in WBCs present in 9 PCs, either from single donors by apheresis (SD-PCs) or from pooled buffy coats (BC-PCs). All PCs were divided in two parts, one of which was irradiated. PCs were stored up to 4 days at room temperature, and samples were withdrawn daily for analysis of apoptosis, of platelet activation (surface and soluble CD62P), and of cytokine concentration (interleukin [IL]-1alpha, IL-1beta, IL-6, IL-8, and tumor necrosis factor alpha). RESULTS: Apoptosis was found to occur with storage in both irradiated and nonirradiated units. Platelet activation increased with storage time and was higher in BC-PCs. The amount of released cytokines was rather variable among PC units. Only IL-8 was consistently found to increase with storage time. CONCLUSIONS: Apoptosis of residual WBCs occurred in PC units as a function of storage time. The amount and the time course of apoptosis seem to correlate with IL-8 release rather than with platelet activation or with the occurrence of febrile nonhemolytic transfusion reactions.

Nuclear matrix protein is released from apoptotic white cells during cold (1-6 degrees C) storage of concentrated red cell units and might induce antibody response in multiply transfused patients.

BACKGROUND: A previous study showed that white cells in blood units undergo apoptosis during storage. STUDY DESIGN AND METHODS: The present study attempts to show the release of nuclear matrix protein (NMP) in the supernatants of red cell units and to determine whether antibodies against nuclear components may be present in multiply transfused patients; the methods employed were enzyme-linked immunosorbent assay, flow cytometry, microscopy, immunoblotting, immunofluorescence, and confocal laser-scanning microscopy. RESULTS: NMP is released from white cells in the supernatant of packed red cell units upon cold storage (1-6 degrees C). The concentration of NMP correlates well with the degree of apoptosis, as analyzed by flow cytometry, nuclear dye staining, and DNA gel electrophoresis. Immunofluorescence also shows that white cells undergoing apoptosis (pre-G(1) peak, as seen by propidium iodide staining and flow cytometry) have an NMP content lower than control cells, which confirms an actual release of NMP. Moreover, immunoblotting analysis and immunofluorescent staining showed that, in 4 of 38 multiply transfused patients, autoantibodies against NMPs were present without any clinical or laboratory sign of autoimmune disease. One of the sera, recognizing a 64-kDa NMP, immunostained nuclear dots that were identified as coiled bodies because of their colocalization with p 80 coilin. CONCLUSION: NMP is released in the supernatant of red cell units. The results obtained from patients suggest that nuclear proteins released during apoptosis, once transfused, may induce an immune response in multiply transfused patients.

White cell apoptosis in packed red cells.

BACKGROUND: After the removal of the buffy coat, packed red cell (RBC) transfusion units still contain white cells that may undergo apoptosis as a result of storage conditions (1-6 degrees C). The aim of the present study was the evaluation of this phenomenon in view of the possible influence it may have on febrile nonhemolytic transfusion reactions. STUDY DESIGN AND METHODS: Three independent methods (microscopy, DNA electrophoresis, and cytometry) were used to evaluate apoptosis in white cells present in 13 RBC units. Of these units, 10 had been collected into CPD/saline-adenine-glucose-mannitol and 3 into CPDA-1; each bag was split in two parts, one of which was irradiated. RBCs were stored at 1 to 6 degrees C, and samples were periodically withdrawn for study. The proliferative capacity of stored lymphocytes was evaluated after phytohemagglutinin stimulation and tritiated thymidine incorporation. RESULTS: Apoptosis was found to occur in both granulocytes and lymphocytes, starting from the first 48 to 72 hours of storage. The choice of the anticoagulant-preservative solution and the effect of irradiation did not influence the amount and the timing of the apoptotic phenomenon. Lymphocyte proliferative capacity was found to decrease sharply with storage time. CONCLUSION: Conditions of storage in RBCs induce consistent apoptosis in residual white cells. The possible clinical implications of the relationships between apoptosis and the induction of biologic response modifiers (that may cause interleukin-mediated febrile non-hemolytic transfusion reactions) and between apoptosis and immune reactions remain to be elucidated.

HPLC determination of glutathione and other thiols in human mononuclear blood cells.

A simple and sensitive HPLC method is proposed for the determination of glutathione (GSH) in human mononuclear cells, based on the derivatization of the tripeptide with Ellman's reagent. The mobile phase was composed of a mixture of methanol and ammonium formate (10:90 v/v, with a flow rate of 1 mL/min). The stationary phase was a C18 (4.6 microns, 250 x 4 mm) reversed phase column. The detection of GSH was performed at 280 nm, resulting in a neat chromatographic peak at 5.8 min. A calibration curve showed good linearity over the concentration range 3 x 10(-6) - 6 x 10(-5) M, with a satisfactory precision. The method was found to yield a quantitative recovery of glutathione (96%), to be sensitive (down to 30 pmol of glutathione per injection) and to have a high precision (R.S.D.% approximately equal to 2). The proposed HPLC method allows for the separation and quantitation of cysteine and N-acetylcysteine, if present in biological samples. Furthermore, the method allows for the determination of total thiol present in human mononuclear cells.

Micromolar zinc affects endonucleolytic activity in hydrogen peroxide-mediated apoptosis.

When damaged by hydrogen peroxide, peripheral blood lymphocytes undergo cell death by apoptosis in the absence of internucleosomal DNA cleavage, while, in the same cells, other apoptosis-inducing treatments bring DNA cleavage to completion. However, the formation of internucleosomal DNA fragments is readily obtained if cells are pretreated with a divalent metal chelator, TPEN, at micromolar concentrations. Since the coadministration of equimolar zinc concentrations abrogates the formation of the ladder, a zinc-inhibitable endonucleolytic activity is accounted for the effect. Most notably, subtraction of zinc ions does not increase the percentage of cells undergoing apoptosis, but rather results in a rescue from death.

Oxidative stress does not mediate heat shock-induced cell damage and apoptosis.

The hypothesis that oxidative damage arising from heat shock might significantly contribute to cell death and in particular to apoptosis has been tested in human peripheral blood lymphocytes. Cellular glutathione content and protein carbonyl groups were measured as indicators of oxidative injury. Cell viability and proliferative capacity were evaluated as measures of irreversible damage. Heat shock caused dose-dependent decreases in cell viability, and apoptotic cell death was found to be a major component of heat-shock-mediated mortality. However, only the more severe heat treatment (1 h, 45°C) caused an immediate decrease in glutathione content. The content in carbonyl groups was not significantly affected by heat shock. N-acetyl-cysteine, when added before the hyperthermic treatment, did increase the glutathione content of the cells, but this did not favourably affect the survival of heat-shocked lymphocytes. It is suggested that oxidative damage is not a significant component of heat shock-mediated cell injury, and that, at least in this experimental model, apoptosis is triggered by stimuli other than an altered redox state of the cell.

Apoptosis of human lymphocytes in the absence or presence of internucleosomal DNA cleavage.

Treatment of human peripheral blood lymphocytes with heat shock, ionising radiation, bleomycin, etoposide, or hydrogen peroxide induced morphological evidence of apoptosis that was associated with the appearance of 50 Kb double-stranded DNA fragments. The apoptotic response elicited by the above agents, with the exception of hydrogen peroxide, was also paralleled by the formation of internucleosomal DNA fragments. This effect of hydrogen peroxide, however, appeared to be confined to human lymphocytes, since apoptosis induced by the oxidant in U937 cells was in fact associated with DNA laddering.

Oxygen radicals induce stress proteins and tolerance to oxidative stress in human lymphocytes.

A set of eight proteins is induced in peripheral blood lymphocytes from normal donors by exposure to hydrogen peroxide or to xanthine oxidase plus hypoxanthine. Four of them (hsp90, hsp72 and proteins 65 and 50 kDa) are also expressed after heat shock, together with proteins 110, 100 and 38 kDa. Among proteins induced after oxidative stress is a 32 kDa protein-probably corresponding to heme oxygenase-1 (HO-1)- and a 27 kDa protein, both known to be induced by reactive oxygen species. Although ionizing radiation is known to generate a number of pro-oxidant intermediates, using our one-dimensional electrophoresis system we can detect no differences in the proteins synthesized after exposure to gamma-ray doses between 5 and 20 Gy as compared with control cells. Pre-exposure to a mild hyperthermia or to moderate oxidative stress significantly increases survival of lymphocytes challenged with high doses of reactive oxygen species, in conditions compatible with a protective rôle exerted by stress proteins. The increase in survival is accompanied by the maintenance of the proliferative capacity of the cells. The physiological rôle played by stress proteins in prevention and repair of damage and the relationships between stress protein induction, oxidative state, proliferation and mode of cell death are discussed.