Applying a novel statistical process control model to platelet quality monitoring.

BACKGROUND: Many countries are implementing universal WBC reduction of blood components Thus, manufacturing procedures must include QC techniques to detect units that fail to meet established standards. STUDY DESIGN AND METHODS: A statistical process control model, based on the exponentially weighted moving average of the cumulative distribution function (CDF-EWMA), was developed to detect shifts in a mean and/or variance of a process. The model's parameters (weights) were optimized to maximize detection of an out-of-control process while minimizing sensitivity to autocorrelation. Validation was performed using a retrospective set of WBC-reduction data obtained from a blood bank. The WBC-reduction process was considered in control when there was 95-percent confidence that more than 95 percent of platelet concentrates would contain less than 1 x 10(6) WBCs (6.0 log WBC) as required by European standards. A sentry setting of 5.7 log WBCs was used to allow earlier detection of an out-of-control process. RESULTS: Graphic output of the CDF-EWMA model provided a continuous update of the probability that a WBC-reduction process was in control. Using the validation data, the model showed that the process was in control until Observation 332, at which point residual WBCs per unit increased. However, the first platelet concentrate to exceed specified criteria (Observation 346) occurred after the model detected that the process was out of control, demonstrating the forecasting value of this model. This deviation corresponded to an equipment failure in a single apheresis instrument. The Shewhart and EWMA techniques were similarly able to detect when the process was out of control using the test data. CONCLUSION: As a statistical process control model, the CDF-EWMA provides real-time estimation of the fraction of components meeting a regulatory limit. It is capable of detecting developing QC problems before units fail to meet regulatory requirements and is a potential alternative to other QC techniques for monitoring WBC reduction of blood components.

Cytomegalovirus infectivity in whole blood following leukocyte reduction by filtration.

Cytomegalovirus (CMV) may be transmitted by transfusion of whole blood and cellular components processed according to standard processing procedures. A need exists to develop new procedures to remove CMV and other leukocyte-borne viruses from donor blood. Ten patients (AIDS/bone marrow transplants) who were CMV antigenemic (virus subsequently confirmed by isolation), donated 50 mL of venous blood within 24 to 72 hours of the initial antigen detection. Twenty-five-milliliter aliquots of each specimen were passed through Purecell Neo Neonatal Leukocyte Reduction Filters (Pall, East Hills, NY). The remaining 25-mL nonfiltered aliquots, as well as the blood filtrates, were subjected to infectivity endpoint determinations. The Purecell Neo filter effected a 3 to 4 log10 leukocyte reduction. CMV input titers ranged from less than 10 to 7.3 x 10(1) median tissue culture infectious dose (TCID50) per milliliter. CMV was not isolated from any postfiltration effluent (i.e., leukocytes, erythrocytes, or plasma). CMV DNA was not detected by nested polymerase chain reaction in 8 of 10 postfiltrate blood specimens. The Purecell Neo filter was efficacious in eliminating or significantly reducing viral (CMV) load in venous blood.

Dimethyl sulfoxide inhibits the binding of granulocyte/macrophage colony-stimulating factor and insulin to their receptors on human leukemia cells.

Numerous agents can induce the terminal differentiation of leukemia cells in vitro, and this action has been found to be of therapeutic value in the treatment of acute promyelocytic leukemia. The proximal site of action of the prototypical chemical inducer of differentiation, dimethyl sulfoxide (DMSO), is not known. In this study, DMSO was found to rapidly cause a 45% to 85% reduction in the specific binding of the growth factors granulocyte/macrophage colony-stimulating factor and insulin to their respective cell surface receptors on HL-60 human acute promyelocytic leukemia cells. Significant inhibition of binding was first observed after 30 min of DMSO treatment, occurred at both 4 degrees C and 37 degrees C, and was due to a DMSO-induced decrease in apparent receptor affinity, with little change in receptor number. A similar inhibition of insulin binding was seen with a second inducer of differentiation, hexamethylene bisacetamide. Kinetic studies demonstrated that DMSO enhanced the rate of insulin dissociation from its receptor. The inhibition of insulin binding by DMSO was also observed in a cell-free extract, suggesting that the effect was not a cell-mediated response to DMSO treatment. DMSO blocked the insulin-induced stimulation of protein tyrosine phosphorylation. These studies suggest that one action of DMSO may be the disruption of the structure and/or organization of cell surface receptors that regulate growth and differentiation.

Evidence for the presence of a growth factor in Dictyostelium discoideum.

Polypeptide hormones, recognized for their ability to regulate cell growth and differentiation, have been classified as growth factors. These growth factors have been extensively described in higher eukaryotic organisms and cell lines [Hedin and Westermark, Cell 37:9-20, 1984]. Here we report the identification and partial characterization of a putative growth factor present in vegetative amoebae of the cellular slime mold Dictyostelium discoideum. A mutant was selected and found to be temperature sensitive due to the absence of an extracellular protein suggestive of a growth factor. The putative growth factor (DGF) is a protein resistant to both heat and strong detergent treatment but sensitive to reducing agents. The physiological significance of DGF is as yet unknown. DGF is of interest both in relation to understanding the events which control cell proliferation in Dictyostelium and in its relationship to other known growth factors.

A Dictyostelium discoideum mutant exhibiting calcium-dependent, high-level detergent resistance.

We report the isolation of a mutant of the cellular slime mold Dictyostelium discoideum that is highly resistant to the lethal action of the nonionic detergent Triton X-100. The resistance is completely dependent on the presence of divalent cations, of which Ca2+ is the most effective.