Search

In concert with the International Society of Hematotherapy and Graft Engineering (ISHAGE), we previously described a set of guidelines for detection of CD34+ cells based on a four-parameter flow cytometry method (CD45 FITC/CD34 PE staining, side and forward angle light scatter). With this procedure, an absolute CD34+ count is generated by incorporating the leukocyte count from an automated hematology analyser (two-platform method). In the present study, we modified the basic ISHAGE method with the addition of a known number of Flow-Count fluorospheres. To reduce errors inherent to sample washing/centrifugation, we implemented ammonium chloride lyse, no-wash no-fix sample processing. These modifications convert the basic protocol into a single-platform method to determine the absolute CD34 count directly from a flow cytometer and form the basis of the Stem-Kit from Coulter/Immunotech. A total of 72 samples of peripheral blood, apheresis packs, and cord blood were analysed and compared using the ISHAGE protocol with or without the addition of fluorescent microspheres. Comparison of methods showed a high correlation coefficient (r=0.99), with no statistically significant difference or bias between methods (P > 0.05). Linearity of the absolute counting method generated an R2 value of 1.00 over the range of 0-250/microl. Precision of the absolute counting method measured at three concentrations of CD34+-stabilised KG1 a cells (Stem-Trol, COULTER) generated a coefficient of variation (C.V.) ranging from 4% to 9.9%. In a further modification of the single-platform method, the viability dye 7-amino actinomycin D was included and demonstrated that both viable and nonviable CD34+ cells could be identified and quantitated. Together, these modifications combine the accuracy and sensitivity of the original ISHAGE method with the ability to produce an absolute count of viable CD34+ cells. It is the accurate determination of this value that is most clinically relevant in the transplant setting. These modifications may improve the interlaboratory reproducibility of CD34 determinations due to the reduction in sample handling and calculation of results.

The Internet and the use of portable computers, mobile phones and tablets have increased the importance of ‘new ways of work’. This work, which is place- and time-independent, can lead to more autonomy and greater flexibility for workers, but it also carries serious physical as well as psychosocial risks according to this working paper. The author of this report focuses on the hidden dangers of these new ways of working: techno-stress, techno-addiction, the blurring of boundaries between work and private life, burn-outs and overtiredness, safety risks and ergonomic problems. The paper analyses the European legislation on safe and healthy working conditions and how it can be applied to this new way of working. Last, but not least, it underlines the importance of this new societal issue for workers’ representatives.

Background: ZAP-70 protein expression has been proposed as a marker for immunoglobulin heavy chain mutational status, which some studies have correlated with disease course in B-cell chronic lymphocytic leukemia (CLL). Studies published to date measuring levels of expression of ZAP-70 intracellular protein using flow cytometry have demonstrated poor performance, as defined by the difference in signal in known positive and negative lymphocyte populations. Methods: A recently published method (Chow S, Hedley DW, Grom P, Magari R, Jacobberger JW, Shankey TV, Cytometry A 2005;67:4–17) to measure intracellular phospho-epitopes was optimized using a design of experiments (DOE) approach to provide the best separation of ZAP-70 expression in positive T- or NK-cells as compared to negative B-cells in peripheral blood samples. A number of commercially available anti-ZAP-70 antibody-conjugates were screened using this methodology, and the antibody-conjugate showing the best performance was chosen to develop a four-color, five antibody assays to measure ZAP-70 levels in whole blood specimens. Results: Using the optimized fixation and permeabilization method, improvement in assay performance (signal-to-noise, S/N) was seen in most of the antibodies tested. The custom SBZAP conjugate gave the best S/N when used in conjunction with this optimized fixation /permeabilization method. In conjunction with carefully standardized instrument set-up protocols, we obtained both intra- and interlaboratory reproducibility in the analysis of ZAP-70 expression in whole blood samples from normal and CLL patients. Conclusions: The development of a sensitive, specific and highly reproducible ZAP-70 assay represents only the first essential step for any clinical assay. The universal implementation of a validated data analysis method and the establishment of methodology-based cutoff points for clinical outcomes must next be established before ZAP-70 protein analysis can be routinely implemented in the clinical laboratory. © 2006 International Society for Analytical Cytology

Background: Central nervous system (CNS) involvement by non-Hodgkin’s lymphoma (NHL) portends a very poor prognosis. There is no consensus in the literature on the “high- risk” features that predict for leptomeningeal disease, and no standardized clinical guidelines exist regarding CNS surveillance, prophylaxis or treatment for patients at increased risk. 2–4 colour flow cytometry (FCM) has been reported to be more sensitive than standard cytology in detecting occult leptomeningeal disease (Blood 2005,105:496). The current study evaluates the utility of a high-sensitivity (5-colour) flow cytometry technique for detecting occult lymphoma cells in the cerebrospinal fluid (CSF) of high-risk patients with NHL. Method: Patients with a new diagnosis of histologically aggressive B or T cell NHL were included in this study if they displayed one or more “high-risk” features for CNS involvement. Patients suspected of CNS relapse of NHL were also eligible for participation. Patients underwent routine staging investigations, with the addition of a diagnostic lumbar puncture (LP) during initial assessment. CSF was tested by standard cytology, cell count and biochemistry, and an additional 5 ml was obtained for analysis by high-sensitivity FCM on a Beckman Coulter FC500. The antibody panel (5 antibodies per tube) was customized according to the phenotype of the lymphoma. The key markers for B cell lymphoma were CD19/kappa/lambda with CD5 or CD10. CD45 was used to identify all white blood cells in the sample. Results: Seventeen patients (8M/9F) with a median age of 59 (range 36–85) have been tested. Patients displayed anywhere from 2–6 “high-risk” features for CNS involvement. These included: HIV positivity (2), primary mediastinal B-cell lymphoma (4), bone marrow (5), multifocal bone (2), paraspinal (1), nasopharyngeal (2) or orbital (1) involvement, elevated serum LDH (12), multiple extranodal sites of disease (5), poor performance status (2), high IPI (3), B-symptoms (9), stage IV disease (11), and otherwise unexplained neurological symptoms (3). 14 patients underwent CSF analysis at time of initial diagnosis, one of whom had cranial nerve palsies secondary to a nasopharyngeal mass extending to the skull base. The other 3 were tested at relapse, transformation, and suspected CNS relapse ultimately diagnosed as a stroke. Despite the presence of these features, CSF analysis was negative for lymphoma cells by both cytology and FCM in all but one of the patients tested. However this patient had very high numbers of circulating lymphoma cells in the peripheral blood (PB), and the positive result was felt to be due to PB contamination of the CSF during a “bloody tap.” One patient with vague neurological symptoms had a negative LP at diagnosis, and later developed frank CNS involvement by lymphoma, but was too unwell to undergo a repeat LP. Conclusions: Given the limited number of patients enrolled thus far and the low prevalence of patients with NHL and CNS involvement (2/17), it is difficult to fully assess the utility of high-sensitivity FCM in the diagnosis of occult leptomeningeal disease. It is of interest that CSF analysis was negative even in the patient with cranial nerve palsies and in the patient who later developed multiple CNS lesions secondary to lymphoma, suggesting that this technique may have limited sensitivity in diagnosing leptomeningeal disease. The systematic screening of high-risk patients cannot yet be recommended as standard clinical practice.