The value of routine bone marrow biopsy in patients with diffuse large B-cell lymphoma staged with PET/CT: a Danish-Canadian study.

BACKGROUND: The added diagnostic and prognostic value of routine bone marrow biopsy (BMB) in patients with diffuse large B-cell lymphoma (DLBCL) undergoing positron emission tomography combined with computed tomography (PET/CT) staging is controversial. PATIENTS AND METHODS: Patients with newly diagnosed DLBCL who underwent both staging PET/CT and BMB were retrospectively identified in British Columbia, Aalborg, and Copenhagen. Original written PET/CT and pathology reports were retrospectively reviewed to determine Ann Arbor stage and outcomes, with and without the contribution of BMB. RESULTS: A total of 530 patients were identified: 146 (28%) had focal bone marrow (BM) lesions on PET/CT and 87 (16%) had positive BMB. Fifty-two of 146 patients (36%) with positive PET/CT had a positive BMB [39 DLBCL, 13 indolent non-Hodgkin lymphoma (iNHL)], while 35 of 384 patients (9%) with negative PET/CT had positive BMB (12 DLBCL, 23 iNHL). BMB upstaged 12/209 (6%) of stage I/II patients to stage IV, although this was the case for only 3 (1%) patients with DLBCL in the BMB. PET/CT identified BM involvement by BMB with sensitivity 60%, specificity 79%, positive predictive value 36%, and negative predictive value 91%. Concordant histological involvement of the BM by DLBCL was associated with worse overall survival and progression-free survival than discordant or no involvement in univariate and multivariate analyses. CONCLUSIONS: In patients with DLBCL, staging PET/CT can miss BM involvement with concordant DLBCL (less common) or discordant iNHL (more common). Routine BMB does not add relevant diagnostic or prognostic value over PET/CT alone in the majority of patients with DLBCL.

Performance comparison of Affymetrix SNP6.0 and cytogenetic 2.7M whole-genome microarrays in complex cancer samples.

The Affymetrix cytogenetic 2.7M whole-genome microarray (Cyto2.7M) detects genomic aberrations. The Cyto2.7M array has increased coverage in regions with cancer-related genes, ~4-fold reduced processing time, and 5-fold reduced input requirements (100 ng) compared to the commonly used Affymetrix SNP6.0 genome-wide microarray (SNP6.0). We set out to compare the performance of these microarrays on cancer samples containing complex genomic changes. We analyzed genomic DNA from 8 lymphoma samples and 1 blood sample using both SNP6.0 and Cyto2.7M microarrays. We compared the arrays with respect to 4 parameters, including detection of copy number variations (CNV), CNV boundaries, the actual copy number (CN) assigned to the aberrations, and loss of heterozygosity. The CN state of selected regions was validated by quantitative PCR. Very high consistency between arrays on all parameters tested was observed, hence only 30 of 224 aberrations disagreed on the CN state, corresponding to a total of ~12 Mb or 0.06% of the analyzed base pairs. Thus, the SNP6.0 and Cyto2.7M arrays are equally well suited to detect genomic aberrations in complex samples such as cancer samples. With reduced processing time and lower input requirements, the Cyto2.7M array enables genomic analysis of samples where only limited DNA is available.

Increased level of both CD4+FOXP3+ regulatory T cells and CD14+HLA-DR⁻/low myeloid-derived suppressor cells and decreased level of dendritic cells in patients with multiple myeloma.

Patients with multiple myeloma (MM) suffer from a general impaired immunity comprising deficiencies in humoral responses, T-cell responses as well as dendritic cell (DC) function. Thus, to achieve control of tumour growth through immune therapy constitutes a challenge. Careful evaluation of the immune status in patients with MM seems crucial prior to active immune therapy. We evaluated the proportion of both, DC, Treg cells and myeloid-derived suppressor cells (MDSC) in peripheral blood from patients with MM at diagnosis and in remission as well as patients with monoclonal gammopathy of undetermined significance (MGUS). We found that the proportion of both myeloid (m) DC and plasmacytoid (p) DC in patients at diagnosis was lowered compared to control donors, while only the proportion of pDC in patients in remission and with MGUS was significantly lower than in controls. The proportion of CD4+FOXP3+ Treg cells was increased in patients at diagnosis and not in patients in remission or with MGUS. Also, Treg cells from patients with MM were functionally intact as they were able to inhibit proliferation of both CD4 and CD8 T cells. Finally, we observed an increase in the proportion of CD14+HLA-DR⁻/low MDSC in patients with MM at diagnosis, illustrating that this cell fraction is also distorted in patients with MM. Taken together, our results illustrate that, both mDC, pDC, Treg cells and MDSC are affected in patients with MM underlining the fact that the immune system is dysregulated as a consequence of the disease.

Acute lymphoblastic leukemia in adolescents between 10 and 19 years of age in Denmark--secondary publication.

INTRODUCTION: Data seem to indicate that young adults with acute lymphoblastic leukemia (ALL) have a better survival when treated with pediatric protocols compared with adult ALL protocols. The purpose of the study was to report the clinical characteristics and outcome of all children and young adults 10-19 years of age diagnosed with ALL in Denmark between 1992 and 2001. MATERIAL: The study includes 99 patients 10-19 years of age with ALL in Denmark during a ten year period found in the complete NOPHO (Nordic Society of Pediatric Hematology and Oncology) registry and through the Danish Cancer Registry and local pathology databases. Data were retrieved by reviewing medical charts of the patients. A total of 61 children (10-14 years) treated on pediatric protocols and 38 young adults (15-19 years) were diagnosed with ALL. Data were reported as of January 1st 2005. RESULTS: There were no difference with respect to the distribution of T-ALL, CNS-leukemia, total white blood count and high risk chromosomal abnormalities between the two groups. There was a statistical significant lower event free survival (p<0.01) and lower overall survival (p<0.01) in young adults compared with 10-14 year-old children (0.38 vs 0.60 and 0.47 vs 0.67). There were more transplant-related deaths in the young adults. Higher treatment intensity in children may be an additional explanatory factor. Children received more prednisone, vincristine and high-dose methotrexate than young adults. CONCLUSION: Young adult patients with ALL might benefit from therapy with pediatric NOPHO ALL protocols.

Management of relapsed multiple myeloma: recommendations of the International Myeloma Working Group.

The prognosis for patients multiple myeloma (MM) has improved substantially over the past decade with the development of new, more effective chemotherapeutic agents and regimens that possess a high level of anti-tumor activity. In spite of this important progress, however, nearly all MM patients ultimately relapse, even those who experience a complete response to initial therapy. Management of relapsed MM thus represents a vital aspect of the overall care for patients with MM and a critical area of ongoing scientific and clinical research. This comprehensive manuscript from the International Myeloma Working Group provides detailed recommendations on management of relapsed disease, with sections dedicated to diagnostic evaluation, determinants of therapy, and general approach to patients with specific disease characteristics. In addition, the manuscript provides a summary of evidence from clinical trials that have significantly impacted the field, including those evaluating conventional dose therapies, as well as both autologous and allogeneic stem cell transplantation. Specific recommendations are offered for management of first and second relapse, relapsed and refractory disease, and both autologous and allogeneic transplant. Finally, perspective is provided regarding new agents and promising directions in management of relapsed MM.

Detection of illegitimate rearrangements within the immunoglobulin light chain loci in B cell malignancies using end sequenced probes.

Translocations involving the immunoglobulin loci are recurring events of B cell oncogenesis. The majority of translocations involve the immunoglobulin heavy chain (IGH) locus, while a minor part involves the immunoglobulin light chain loci consisting of the kappa light chain (IGK) located at 2p11.2 and the lambda light chain (IGL) located at 22q11.2. We characterised BAC clones, spanning the IGK and IGL loci, for detection of illegitimate rearrangements by fluorescence in situ hybridisation (FISH). Within the IGL region we have identified six end sequenced probes (22M5, 1152K19, 2036J16, 3188M21, 3115E23 and 274M7) covering the variable (IGLV) cluster and two probes (165G5 and 31L9) covering the constant (IGLC) cluster. Within the IGK region four probes (969D7, 316G9, 122B6 and 2575M21) have been identified covering the variable (IGKV) cluster, and one probe (1021F11) covering the IGK constant (IGKC) cluster. A series of 24 cell lines of different origin have been analysed for the presence of translocations involving the immunoglobulin light chain loci by dual-colour FISH where the split of the variable cluster and the constant cluster indicated a translocation. Probes established in this study can be used for universal screening of illegitimate rearrangements within the immunoglobulin light chain loci in B cell malignancies.

Short-term liquid marrow cultures are supported by a mixture of haematopoietic cytokines but do not purge for acute myeloid or lymphoid leukemic marrow cells.

Short-term liquid marrow culture (STLMC) is a potential source for autografting in leukemia. In a preclinical setting, including candidates for autologous marrow transplantation, we have studied STLMC supported by a selected mixture of clinical available recombinant human haematopoietic growth factors. STLMC of leukemic marrow cells were prospectively performed to evaluate the purging effect. Bone marrow cells cultured and supported by the selected mixture of rhIL-3/rhGM-CSF/rhEpo revealed an increased number of day 10-12 cultured cells, parallelled by an increased proliferation rate when compared to unstimulated cultures. The median number of myeloid progenitors recognized as day 7 and day 14 granulocyte-macrophage colony-forming units (day 7/14 GM-CFU) was significantly increased in the supported STLMC to 145/305 from 105/115 per ml culture (n = 7, p < 0.01). Further addition of rhKL did not enhance the numbers of day 7 or day 14 GM-CFUs per ml culture. In no instance was the number of clonogenic cells at the end of culture greater than the input day 0, except in cultures of purified CD34-positive marrow progenitors which resulted in an expansion of late myeloid progenitors. Cytokine-supported cultures of leukemic marrow cells from acute myeloid (n = 14) and lymphoblastic (n = 7) leukemia patients were established at the time of diagnosis. In the supported cultures, the cell number increased for myeloblast but was unchanged for lymphoblast leukemic marrow cells compared to non-supported cultures. Immunophenotypic and cytogenetic studies of selected leukemic cell samples identified unchanged myeloid or slightly reduced frequencies of lymphoblastic leukemic cells at the end of culture. This preclinical study supports the idea that the addition of a mixture of clinical available haemopoietic cytokines to STLMC increases the recovery of detectable myeloid progenitors which may enhance myeloid regeneration after autografting. No substantial selective loss of myeloid leukemic cells was found in the cytokine-supported short-term culture system.

CD34+ megakaryoblastic leukaemic cells are CD38-, but CD61+ and glycophorin A+: improved criteria for diagnosis of AML-M7?

The aim of this flow cytometry study in acute megakaryoblastic leukaemia (AML-M7) was to describe the membrane phenotype of CD34+ progenitor subsets and compare these with the phenotypes expressed by other AML FAB types. Following conventional histopathological diagnosis mononuclear cells from bone marrow and blood were examined in seven patients with AML-M7 and compared with results from 26 sequential patients with AML-M0 to AML-M6. The CD34+ subsets in AML-M7 patients differed from that of patients with AML-M0 to AML-M6 as the CD34+ CD61+ and the CD34+ Glycophorin A+ subsets were median 31% and 20%, respectively, compared to 4% and 2% in the AML-M0 to AML-M6 (P = 0.0005). Only 1% of the CD34+ progenitors were CD34+ CD38+ in AML-M7 compared to 72% in other AML subtypes (P < 0.000). These findings suggest that the CD34+ cell compartment in AML-M7 consists of early lineage-specific progenitors. In conclusion, flow cytometry analysis of CD34+ subsets may improve the diagnostic safety in AML-M7 and consequently the prognostic significance of immunophenotyping in acute leukaemia.

Quantitation of minimal residual disease in multiple myeloma using an allele-specific real-time PCR assay.

OBJECTIVE: To develop a real-time PCR method, based on the 5'nuclease TaqMan technology, for quantitation of clonal cells in multiple myeloma (MM). MATERIALS AND METHODS: The real-time quantitative PCR method incorporates both an allele-specific oligonucleotides (ASO) primer and an ASO dual-labeled fluorogenic probe (ASO TaqMan probe). The ASO primer and probe corresponded to the complementary determining region 3 (CDR3) of the rearranged immunoglobulin heavy chain gene (IgH). With the use of a sequence detector, PCR product accumulation was measured through the ASO TaqMan probe. The real-time PCR method was compared with flow cytometric quantitation of myeloma plasma cells. RESULTS: The application of the real-time quantitative ASO IgH PCR method is illustrated by a sequential analysis of minimal residual disease (MRD) in bone marrow (BM) samples from myeloma patients undergoing peripheral blood stem cell (PBSC) transplantation. The real-time PCR method was able to quantitate residual malignant cells in BM samples from patients who were considered to be in complete remission. Further, it was illustrated that a potential problem in determining tumor cell content in myeloma BM samples is the heterogeneous infiltration of the marrow. CONCLUSION: The application of the real-time PCR method provides a sensitive, highly specific, and reproducible quantitation of myeloma cells.

Priming with recombinant human hematopoietic cytokines before bone marrow harvest expands in vivo and enhances ex vivo recovery of myeloid progenitors in short-term liquid cultures.

BACKGROUND AND AIM: Short-term liquid marrow cultures (STLMC) are a potential source for autografting. We have previously shown that the quality of such grafts from transplantation candidates may be improved by hematopoietic cytokine support, especially if purified CD34-positive progenitors are cultured. The aim of this preclinical work was to quantitate ex vivo recovery of myeloid progenitors (colony-forming units-granulocyte/macrophage [CFU-GM]) in STLMC before and after short-term, in vivo treatment with recombinant human granulocyte colony-stimulating factor (rhG-CSF), granulocyte-macrophage colony-stimulating factor (rhGM-CSF), or interleukin-3 (rhIL-3). EXPERIMENTAL SETUP: Twenty-two sequential patients in marrow remission for hematological malignancies and eligible for autologous marrow transplantation received rhG-CSF or rhGM-CSF for 5 days or rhIL-3 for 10 days before marrow harvest. Marrow samples before and after in vivo priming were studied for CFU-GM in pre- and post-STLMC. RESULTS: After priming with rhG-CSF, rhGM-CSF, or rhIL-3, the number of isolated light-density cells increased nine-, six-, and two-fold, respectively. The total number of sampled (18 mL marrow) myeloid progenitors preculture (day 7/14 CFU-GM x 10(4) increased significantly from median 0.7/1.1 before to 37.3/26.7 after priming with rhG-CSF (n = 8) and from 5.6/3.4 before to 46.6/44.9 after priming with rhGM-CSF (n = 8) but remained unchanged (3.7/1.5 to 3.6/5.7) after priming with rhIL-3 (n = 6). The number of myeloid progenitors postculture (day 7/14 CFU-GM x 10(4) per 18 mL marrow) in cytokine-supported STLMC significantly increased from median 0.3/0.6 before to 7.0/5.3 after priming with rhG-CSF and from 1.9/1.6 before to 24.4/14.4 after priming with rhGM-CSF but remained unchanged (0.4/0.6 to 0.4/0.2) after priming with rhIL-3. Cytokine-primed and purified CD34+ marrow cells may be expanded in STLMC by a cytokine-driven differentiation into late myeloid progenitors and endstage cells. CONCLUSION: In vivo priming of bone marrow cells by hematopoietic cytokines significantly increases the recovery of harvested pre- and postculture myeloid progenitors. During cytokine-supported STLMC, early myeloid progenitors may differentiate into a "very late" progenitor pool with a potential for fast marrow regeneration. The number of such progenitors in cytokine-supported short-term liquid cultures may be sufficient for fast myeloid engraftment and complete peripheral blood or marrow stem-cell support after high-dose chemotherapy.

A methodological study of E-rosette formation using AET-treated sheep red blood cells.

The influence of some of the well knwon technical variables on the E-rosette technique was examined using sheep red blood cells (SRBC) treated with 2-aminoethylisothiouronium bromide (AET). With AET treatment, E-rosette formation becomes less dependent on time and temperature and on the presence of serum. The mechanical stability of the rosettes is enhanced, and the number of SRBC attached to each rosette-forming lymphocyte (RFC) is markedly increased, leading to a sharper distinction between RFC and non-RFC. Ultimately, significantly more E-receptor carrying lymphocytes become detectable. Evidence is provided that the specificity of the E-rosette technique is unchanged after AET treatment of SRBC, in spite of the enhanced binding. A simple and reliable method for E-RFC identification is documented.

Isolation of human T and B lymphocytes by E-rosette gradient centrifugation. Characterization of the isolated subpopulations.

Some methodological aspects of E-rosette gradient centrifugation for separation of human B and T lymphocytes are described. Treatment of sheep red blood cells (SRBC) with 2-aminoethylisothiouronium bromide (AET) accelerates and enhances E-rosette formation providing an effective and time saving method which takes less than 2 h to perform. Depletion of E-rosette forming cells (E-RFC) is almost complete, leaving less than 1% of the initial E-RFC at the interphase layer. By use of the lymphocyte donor's autologous serum containing naturally occurring anti-SRBC antibody and complement the SRBC in the rosetted T lymphocyte fraction are easily and completely lysed without damage to the lymphocytes. This procedure is shown to have little effect on the properties of the isolated T cells. The isolated lymphocyte subpopulations have been characterized by tests for lymphocyte and monocyte markers.

Activation of human alloreactive cytotoxic precursor T lymphocytes.

The requirements for allogeneic T-cell activation have been studied in experiments with T and/or B cells as stimulator. Although target determinants (TDs, defined by CTL effectors in CML) are present on B and T cells used as target cells, this study indicates that TDs are functionally different when expressed on B and T cells used as stimulator cells, as only B cells can activate CTL precursors. Further, the study confirms that inducing TDs and strong lymphocyte-activating determinants (LADs, defined by proliferation in MLC) can be distinct structures found on two different stimulator B cells. The study suggests that binding of cytotoxic precursor T cells to TDs per se does not allow any detectable activation or start of proliferation and differentiation but requires another function of the stimulator cells in the non-T-cell compartment. The nature of this function is unknown, but it is the background for the first signal received by the TD-specific clones of CTL precursors, resulting in the expression of growth receptors for T-cell growth factor or interleukin 2 which is the second signal necessary for clonal expansion and differentiation.

A European reference protocol for quality assessment and clinical validation of autologous haematopoietic blood progenitor and stem cell grafts.

Recently, the regulatory authorities have begun to show interest in haematopoietic stem cell products. On a professional rather than a regulatory basis, the International Society for Hematotherapy and Graft Engineering (ISHAGE) has established the Foundation for the Accreditation of Haematopoietic Cell Therapy (FACHT), which has drawn up guidelines for standards and accreditation of such activity. In Europe, the regulatory environment with regard to haematopoietic stem cell grafts, processing and storage are currently less stringent. However, in 1998 the European Joint Accreditation Committee Euro-ISHAGE/EBMT (JACIE) prepared a regulatory document 'Standards for Blood and Marrow Progenitor Cell Collection, Processing and Transplantation' which was approved by the EBMT General Assembly. The major objectives were to promote quality of medical and laboratory practice in haematopoietic progenitor cell transplantation. The standards extend and detail the pre-existing activity of EBMT centres including all phases of collection, processing and administration of these cells. This is the platform for the proposed reference protocol for CD34(+) cell enumeration and clinical validation of quality assessment to ensure that appropriate standards of work and product quality are established and will be maintained.

Individual quality assessment of autografting by probability evaluation: a model estimated by analysis of graft-related end points in 204 patients with malignancies.

Haematological toxicity is considered a secondary end point important for graft evaluation - in today's practice graft evaluation focuses on the primary impact of health economic end points. This report illustrates the benefit of combining CD34 enumeration and demographic as well as disease-related variables in models for individual quality assessment of autografting following high-dose therapy. A total of 24 centres in Scandinavia enrolled 204 patients younger than 67 years who received high-dose therapy with autologous peripheral blood stem cell transplantation. Using the binary Logistic Regression Analysis, the prognostic value of diagnostic demographic variables, therapy and graft-related factors was entered into a multivariate analysis and the final significant models were used to estimate probabilities for acceptable or unacceptable outcome among different patient scenarios. The model that estimated post-transplant efficacy by selected primary end points (time on antibiotics and use of transfusions) includes six independent variables related to sex, age, disease, conditioning, growth factor administration, and graft CD34+ cell number. The model that estimated transplantation-related toxicity by selected secondary end points (time to blood cell recovery) included four independent variables related to age, disease, growth factor administration and graft CD34+ cell number.

Donor alloreactivity may predict acute graft-versus-host disease in patients receiving marrow transplants from HLA identical siblings.

In a study of 27 patients receiving marrow grafts from HLA-identical donors, the immune response capacity of donor T cells measured pretransplant was compared with the incidence and severity of post-transplant acute graft-versus-host disease (GVHD). Donors were categorized as either high responders or low responders based on their responsiveness to monocyte-dependent soluble antigens and to alloantigens expressed on a B-lymphoblastoid cell line. The high or low responder status of donor cells as defined by response to soluble antigen did not correlate with the incidence of acute GVHD in patients receiving transplants from these donors. The responder status of donor cells as defined by response to alloantigen, however, did correlate with incidence of post-transplant GVHD. Of nine patients receiving marrow from low responder donors, only two developed GVHD (Grades I-II). Conversely, of 18 patients receiving marrow from high responder donors, 13 developed GVHD (Grade I-IV) (chi 2 = 3.71; d.f. = 1, p = 0.05), with nine of the 13 developing moderate to severe Grade II-IV GVHD (chi 2 = 2.60; d.f. = 1, p = 0.10). These results indicate that pretransplant testing of donor T cells for response to alloantigen may identify those patients who will be at increased risk of developing clinically significant acute GVHD following marrow transplantation. Since there was only a trend toward statistical significance, however, these data require confirmation in a prospective study with larger number of patients.

Flow cytometric detection of growth factor receptors in autografts and analysis of growth factor concentrations in autologous stem cell transplantation: possible significance for platelet recovery.

In order to improve prediction of hematopoietic recovery, we conducted a pilot study, analyzing the significance of growth factor receptor expression in autografts as well as endogenous growth factor levels in blood before, during and after stem cell transplantation. Three early acting (stem cell factor (SCF), Flt3 ligand (Flt3) and fetal antigen 1 (FA1)) and three lineage-specific growth factors (EPO, G-CSF and thrombopoietin (Tpo)) were analyzed by ELISA in 16 patients with multiple myeloma (MM) and 16 patients with non-Hodgkin's lymphoma (NHL). The relative number of SCF, Flt3, Tpo and G-CSF receptor positive, CD34+ progenitor cells were measured by flow cytometry in the leukapheresis product used for transplantation in a subgroup of 15 patients (NHL, n = 8, MM, n = 7). Three factors were identified as having a significant impact on platelet recovery. First, the level of Tpo in blood at the time of the nadir (day +7). Second, the percentage of re-infused thrombopoietin receptor positive progenitors and finally, the percentage of Flt3 receptor positive progenitors. On the other hand, none of the analyzed factors significantly predicted myeloid or erythroid recovery. These findings need to be confirmed in prospectively designed studies.

Impact of high-dose chemotherapy on antigen-specific T cell immunity in breast cancer patients. Application of new flow cytometric method.

The present study analyses the influence of high-dose chemotherapy (HD) and autologous stem cell transplantation on natural and vaccine-induced specific immunity in breast cancer patients. Peripheral blood was collected from five breast cancer patients at serial time points in connection with treatment and in a follow-up period of 1 year. The frequencies of CD8+ and CD4+ T cells responsive to cytomegalovirus (CMV), varicella zoster virus (VZV), and tetanus in antigen-activated whole blood were determined by flow cytometric analysis of CD69, TNF alpha, IFN gamma and IL-4 expression. Mononuclear cells were labelled with PKH26 dye and the CMV, VZV, and tetanus toxoid-specific proliferation of T cell subpopulations was analysed by flow cytometry. In none of the patients did the treatment result in loss of overall T cell reactivity for any of the antigens. Prior to chemotherapy 5/5 patients possessed TNF alpha expressing T cells specific for CMV, 4/5 for VZV, and 3/5 for tetanus. One year after stem cell transplantation all patients possessed TNF alpha expressing T cells specific for CMV, VZV and tetanus. The highest percentages of cytokine-responding T cells were seen after stimulation with CMV antigen. In general, the lowest reactivity (close to zero) was measured in G-CSF-mobilised blood at the time of leukapheresis. In spite of a continuously reduced CD4 to CD8 ratio after transplantation, recovery of CD4+ T cells usually occurred prior to CD8+ recovery and often to a higher level. The study demonstrates that natural as well as vaccine-induced specific immunity established prior to HD can be regained after stem cell transplantation. These data indicate that introduction of a preventive cancer vaccination in combination with intensive chemotherapy may be a realistic treatment option.

Assessing agreement between CD34 enumeration by flow cytometry and volumetric analysis.

Prior to replacement of an established method for CD34 enumeration by an alternative approach, evaluation of the agreement between the methods is essential. In this study, the comparison of two assays was evaluated according to the recommendation of Bland and Altman describing the agreement between two methods where the true value is not known. CD34 enumeration was performed on blood or leukapheresis product from 105 patients by flow cytometry (dual platform assay) and volumetric analysis (single platform assay). Both the flow cytometric and the volumetric analysis showed poor reproducibility for measures lower than approximately 9 CD34+ cells/mm3. For values higher than 29 CD34+ cells/mm3, evaluation of the agreement demonstrated a difference between the single and dual platform assay, where CD34 enumeration by the volumetric analysis demonstrated values 73-80% of the flow cytometric value. The difference between the two assays could be due to several technical pitfalls which are discussed.

A comparative study of sequential priming and mobilisation of progenitor cells with rhG-CSF alone and high-dose cyclophosphamide plus rhG-CSF.

Stem cell mobilisation can be achieved either by administration of rhG-CSF alone or after high-dose cyclophosphamide (HDCy) plus rhG-CSF. We have compared both mobilisation procedures intra-individually in 43 patients with haematological malignancies. Furthermore, the toxicity data were registered. The CD34+ cell yield was higher after mobilisation with HDCy plus rhG-CSF than after rhG-CSF alone in 21 out of 22 patients who were actually harvested after both procedures. If a patient mobilised insufficiently after rhG-CSF alone, the yield of CD34+ cells after the following HDCy priming was lower compared to patients who mobilised sufficiently after rhG-CSF priming alone. In 12 patients with B cell malignancies a reduced number of B cells such as CD10+, CD19+, CD20+ cells in bone marrow as well as in leukapheresis products was observed after HDCy plus rhG-CSF compared to rhG-CSF alone. Toxicity data revealed HDCy as a relatively toxic priming regimen with all patients hospitalised and 74% experiencing neutropenic fever and administration of intravenous antibiotics. In two patients, seizure-like episodes were observed during cyclophosphamide bolus infusion. In conclusion, HDCy increased the yield of CD34+cell and reduced B cells in leukapheresis products indicating reduced tumour cell load compared with rhG-CSF priming alone. The efficacy of HDCy priming is limited by its profound toxicity and morbidity. Studies evaluating efficacy and safety of lower doses of cyclophosphamide are needed. Bone Marrow Transplantation (2000) 26, 717-722.