Comparative analysis of genome-scale, base-resolution DNA methylation profiles across 580 animal species

Methylation of cytosines is a prototypic epigenetic modification of the DNA. It has been implicated in various regulatory mechanisms across the animal kingdom and particularly in vertebrates. We mapped DNA methylation in 580 animal species (535 vertebrates, 45 invertebrates), resulting in 2443 genome-scale DNA methylation profiles of multiple organs. Bioinformatic analysis of this large dataset quantified the association of DNA methylation with the underlying genomic DNA sequence throughout vertebrate evolution. We observed a broadly conserved link with two major transitions-once in the first vertebrates and again with the emergence of reptiles. Cross-species comparisons focusing on individual organs supported a deeply conserved association of DNA methylation with tissue type, and cross-mapping analysis of DNA methylation at gene promoters revealed evolutionary changes for orthologous genes. In summary, this study establishes a large resource of vertebrate and invertebrate DNA methylomes, it showcases the power of reference-free epigenome analysis in species for which no reference genomes are available, and it contributes an epigenetic perspective to the study of vertebrate evolution.

Response to intravenous racemic ketamine after switch from intranasal (S)-ketamine on symptoms of treatment-resistant depression and post-traumatic stress disorder in Veterans: A retrospective case series

BACKGROUND

Racemic (R,S)-ketamine is a glutamatergic drug with potent and rapid acting antidepressant effects. An intranasal formulation of (S)-ketamine was recently approved by the US Food and Drug Administration (FDA) to be used in individuals with treatment-resistant depression (TRD). There are no data directly comparing outcomes on depression or other comorbidities between these two formulations of ketamine. However, recent meta-analyses have suggested that IV racemic ketamine may be more potent than IN-(S)-ketamine.

METHODS

We retrospectively analyzed clinical outcomes in 15 Veterans with comorbid TRD and post-traumatic stress disorder (PTSD) who underwent ketamine treatment at the VA San Diego Neuromodulation Clinic. All Veterans included in this analysis were given at least 6 intranasal (IN)-(S)-ketamine treatments prior to switching to treatment with IV racemic ketamine.

RESULTS

Veterans receiving ketamine treatment ( across both IN-(S)-ketamine and IV-(R,S)-ketamine) showed significant reductions in both the Patient Health Questionnaire-9 (PHQ-9), a self-report scale measuring depression symptoms (rm ANOVA F(14,42) = 12.6, p < 0.0001), and in the PTSD checklist for DSM-5 (PCL-5), a self-report scale measuring PSTD symptoms (rm ANOVA F(13,39) = 5.9, p = 0.006). Post hoc testing revealed that PHQ-9 scores were reduced by an average of 2.4 ± 1.2 compared to baseline after (S)-ketamine treatments (p = 0.1) and by an average of 5.6 ± 1 after IV-ketamine treatments (p = 0.0003) compared to pretreatment baseline scores. PCL-5 scores were reduced by an average of 4.3 ± 3.3 after IN (S)-ketamine treatments (p = 0.6) and 11.8 ± 3.5 after IV-ketamine treatments (p = 0.03) compared to pretreatment baseline scores.

CONCLUSIONS

This work suggests that off-label IV-(R,S)-ketamine could be considered a reasonable next step in patients who do not respond adequately to the FDA-approved IN-(S)-ketamine. Further double-blinded, randomized controlled trials are warranted to assess whether IV racemic ketamine is more effective than IN-(S)-ketamine.

Detection and Monitoring of Lineage-Specific Chimerism by Digital Droplet PCR-Based Testing of Deletion/Insertion Polymorphisms

Analysis of specific leukocyte subsets for post-transplantation monitoring of chimerism provides greater sensitivity and clinical informativeness on dynamic changes in donor- and recipient-derived cells. Limitations of the most commonly used approach to chimerism testing relying on PCR-based analysis of microsatellite markers prompted us to assess the applicability of digital droplet (dd) PCR amplification of deletion/insertion polymorphisms (DIPs) for lineage-specific chimerism testing in the related stem cell transplantation setting, where the identification of informative markers facilitating the discrimination between donor-derived and recipient-derived cells can be challenging. We analyzed 100 genetically related patient-donor pairs by ddPCR analysis using commercially available DIP kits including large sets of polymorphic markers. At least 1 informative marker was identified in all related pairs analyzed, and 2 or more discriminating markers were detected in the majority (82%) of instances. The achievable detection limit is dependent on the number of cells available for analysis and was as low as 0.1% in the presence of ≥20,000 leukocytes available for DNA extraction. Moreover, the reproducibility and accuracy of quantitative chimerism analysis compared favorably to highly optimized microsatellite assays. Thus, the use of ddPCR-based analysis of DIP markers is an attractive approach to lineage-specific monitoring of chimerism in any allogeneic transplantation setting.

Flow-cytometric minimal residual disease monitoring in blood predicts relapse risk in pediatric B-cell precursor acute lymphoblastic leukemia in trial AIEOP-BFM-ALL 2000

BACKGROUND

Flow-cytometric monitoring of minimal residual disease (MRD) in bone marrow (BM) during induction of pediatric patients with acute lymphoblastic leukemia (ALL) is widely used for outcome prognostication and treatment stratification. Utilizing peripheral blood (PB) instead of BM might be favorable, but data on its usefulness are scarce.

PROCEDURE

We investigated 1303 PB samples (days 0, 8, 15, 33, and 52) and 285 BMs (day 15) from 288 pediatric ALL patients treated in trial AIEOP-BFM ALL 2000. MRD was assessed by four-color flow cytometry and evaluated as relative, absolute, and kinetic result.

RESULTS

In B-ALL only, PB measures from early time points correlated with relapse incidence (CIR). Best separation occurred at threshold <1 blast/μL at day 8 (5-year CIR 0.02 ± 0.02 vs 0.12 ± 0.03; P = 0.044). Patients with highest relapse risk were not distinguishable, but PB-MRD at days 33 and 52 correlated with prednisone response and postinduction BM-MRD by PCR (P < 0.001). Kinetic assessment did not convey any advantage. In multivariate analysis including day 15 BM-MRD, PB-MRD measures lost statistical power.

CONCLUSIONS

In summary, PB-MRD in pediatric B-ALL correlates with outcome and risk parameters, but its prognostic significance is not strong enough to substitute for BM assessment in AIEOP-BFM trials. It might, however, be valuable in treatment environments not using multifaceted risk stratification with other MRD measures.

Gliomasphere marker combinatorics: multidimensional flow cytometry detects CD44+/CD133+/ITGA6+/CD36+ signature

Glioblastoma is the most dangerous brain cancer. One reason for glioblastoma's aggressiveness are glioblastoma stem‐like cells. To target them, a number of markers have been proposed (CD133, CD44, CD15, A2B5, CD36, CXCR4, IL6R, L1CAM, and ITGA6). A comprehensive study of co‐expression patterns of them has, however, not been performed so far. Here, we mapped the multidimensional co‐expression profile of these stemness‐associated molecules. Gliomaspheres – an established model of glioblastoma stem‐like cells – were used. Seven different gliomasphere systems were subjected to multicolor flow cytometry measuring the nine markers CD133, CD44, CD15, A2B5, CD36, CXCR4, IL6R, L1CAM, and ITGA6 all simultaneously based on a novel 9‐marker multicolor panel developed for this study. The viSNE dimensionality reduction algorithm was applied for analysis. All gliomaspheres were found to express at least five different glioblastoma stem‐like cell markers. Multi‐dimensional analysis showed that all studied gliomaspheres consistently harbored a cell population positive for the molecular signature CD44+/CD133+/ITGA6+/CD36+. Glioblastoma patients with an enrichment of this combination had a significantly worse survival outcome when analyzing the two largest available The Cancer Genome Atlas datasets (MIT/Harvard Affymetrix: P = 0.0015, University of North Carolina Agilent: P = 0.0322). In sum, we detected a previously unknown marker combination – demonstrating feasibility, usefulness, and importance of high‐dimensional gliomasphere marker combinatorics.

Relevance of flow cytometric enumeration of post-thaw leucocytes: influence of temperature during cell staining on viable cell recovery

BACKGROUND AND OBJECTIVES

Our post-thaw cell recovery rates differed substantially in interlaboratory comparisons of identical samples, potentially due to different temperatures during cell staining.

MATERIALS AND METHODS

Viable CD34(+) cells and leucocyte (WBC) subtypes were quantified by multiparameter single-platform flow cytometry in leucapheresis products collected from 30 adult lymphoma and myeloma patients, and from 10 paediatric patients. After thawing, cells were prepared for analysis within 30 min between thawing and acquisition, at either 4°C or at room temperature.

RESULTS

For cell products cryopreserved in conventional freezing medium (10% final DMSO), viable cell recovery was clearly lower after staining at 4°C than at RT. Of all WBC subtypes analysed, CD4(+) T cells showed the lowest median recovery of 4% (4°C) vs. 25% (RT), followed by CD3, CD34 and CD8 cells. The recovery was highest for CD3γδ cells with 44% (4°C) vs. 71% (RT). In the 10 samples cryopreserved in synthetic freezing medium (5% final DMSO), median recovery rates were 89% for viable CD34 (both at 4°C and RT) and 79% (4°C) vs 68% (RT) for WBC.

CONCLUSIONS

The post-thaw environment and, potentially, the cryoprotectant impact the outcome of cell enumeration, and results from the analysis tube may not be representative of the cells infused into a patient.

Differential DNA Methylation Analysis without a Reference Genome

Genome-wide DNA methylation mapping uncovers epigenetic changes associated with animal development, environmental adaptation, and species evolution. To address the lack of high-throughput methods for DNA methylation analysis in non-model organisms, we developed an integrated approach for studying DNA methylation differences independent of a reference genome. Experimentally, our method relies on an optimized 96-well protocol for reduced representation bisulfite sequencing (RRBS), which we have validated in nine species (human, mouse, rat, cow, dog, chicken, carp, sea bass, and zebrafish). Bioinformatically, we developed the RefFreeDMA software to deduce ad hoc genomes directly from RRBS reads and to pinpoint differentially methylated regions between samples or groups of individuals (http://RefFreeDMA.computational-epigenetics.org). The identified regions are interpreted using motif enrichment analysis and/or cross-mapping to annotated genomes. We validated our method by reference-free analysis of cell-type-specific DNA methylation in the blood of human, cow, and carp. In summary, we present a cost-effective method for epigenome analysis in ecology and evolution, which enables epigenome-wide association studies in natural populations and species without a reference genome.

Human adenovirus-specific γ/δ and CD8+ T cells generated by T-cell receptor transfection to treat adenovirus infection after allogeneic stem cell transplantation

Human adenovirus infection is life threatening after allogeneic haematopoietic stem cell transplantation (HSCT). Immunotherapy with donor-derived adenovirus-specific T cells is promising; however, 20% of all donors lack adenovirus-specific T cells. To overcome this, we transfected α/β T cells with mRNA encoding a T-cell receptor (TCR) specific for the HLA-A*0101-restricted peptide LTDLGQNLLY from the adenovirus hexon protein. Furthermore, since allo-reactive endogenous TCR of donor T lymphocytes would induce graft-versus-host disease (GvHD) in a mismatched patient, we transferred the TCR into γ/δ T cells, which are not allo-reactive. TCR-transfected γ/δ T cells secreted low quantities of cytokines after antigen-specific stimulation, which were increased dramatically after co-transfection of CD8α-encoding mRNA. In direct comparison with TCR-transfected α/β T cells, TCR-CD8α-co-transfected γ/δ T cells produced more tumor necrosis factor (TNF), and lysed peptide-loaded target cells as efficiently. Most importantly, TCR-transfected α/β T cells and TCR-CD8α-co-transfected γ/δ T cells efficiently lysed adenovirus-infected target cells. We show here, for the first time, that not only α/β T cells but also γ/δ T cells can be equipped with an adenovirus specificity by TCR-RNA electroporation. Thus, our strategy offers a new means for the immunotherapy of adenovirus infection after allogeneic HSCT.

Robust multi-parameter single-platform quantification of myeloid and B-lymphoid CD34 progenitor cells in all clinical CD34 cell sources and in thawed PBSC

As B-lymphoid progenitor cells do not give rise to in vitro colony formation and are unlikely to support myeloid engraftment, we validated a five-color extension of the single platform Stem Cell Enumeration (SCE) kit, to routinely quantify myeloid and B-lymphoid progenitor cells. Fresh samples (n > 20 each) of granulocyte colony stimulating factor mobilized blood (peripheral blood (PB)), cord blood (CB), bone marrow (BM), and apheresis products (APs) were stained in TruCOUNT™ tubes and the results were compared with those from the two-color CD45/CD34 reagent combination and the three-color SCE kit. To address repeatability, 10 samples from one AP were prepared by four technicians. Aliquots (n = 15) of four frozen AP were analyzed after thawing. Excellent correlations were observed between the three kits (R(2) > 0.99), for the quantification of white blood cells and total CD34. The extended kit showed considerable amounts of B-lymphoid progenitors in all CD34 sources (0-20% of all CD34 in PB, AP, and CB; 3-90% in BM). Very similar results were obtained when the same sample was prepared by different technicians. After thawing of frozen AP, the recovery of viable cells varied depending on the freezing medium employed, but the results from the different quantification methods were identical. Most non-viable cells were clearly identified with 7 Aminoactinomycin D (7AAD) but an additional gate in the forward scatter/side scatter was necessary to address dead cells negative for 7AAD. The extended SCE kit allows rapid and exact quantification of viable B-lymphoid and myeloid CD34(+) cells in all cell sources and in thawed stem cell harvests, and may thus improve the correlation between CD34 number and engraftment kinetics.

Novel single-platform multiparameter FCM analysis of apoptosis: Significant differences between wash and no-wash procedure

FCM is a generally accepted tool to analyze apoptosis. Unfortunately, the cell preparation of all commercial kits available includes cell washing known to cause cell loss which is most likely to affect apoptotic cells in particular. To address this, we developed a seven-color single-platform no-wash analysis technique and compared the results with those from an analogous procedure including cell washing. A five-color mAb cocktail was employed to address target cells by surface labeling, Yo-PRO-1® and DAPI were used to discriminate apoptotic and necrotic from viable cells. Cells were quantified on the basis of internal-standard fluorescent beads. Jurkat cells ACC 282 treated with camptothecin were employed to establish the staining procedure, which was then applied to blood cells collected by extracorporeal apheresis and treated with UV irradiation. Data evaluation showed that although each method by itself was highly reproducible (R(2) = 0.973), the numbers of apoptotic cells detected with the no-wash procedure were significantly higher than those obtained after cell washing (P = 6.6 E(-5), Wilcoxon Test). In addition, the observed differences increased with higher cell numbers (Bland and Altmann). We conclude that the described test is a feasible and reliable tool for apoptosis measurement and it provides results that are definitely closer to the truth than those obtained from kits that require cell washing.

Flow cytometric monitoring of hematopoietic reconstitution in myeloablated patients following allogeneic transplantation

BACKGROUND

We report a routine flow cytometric (FACS) approach to quantify circulating leukocytes (NC) in myeloablated patients before and during regeneration after allogeneic transplantation of either whole bone marrow (BM) or of highly purified (> 99%) blood-derived CD34(+) cells (PBSC).

METHODS

Blood samples were analyzed daily between infusion of the transplant and hematopoietic reconstitution. Significant differences in the composition of NC types and CD34(+) cells were observed between the two CD34 sources. The detection threshold for NC was roughly 1 cell per w L blood.

RESULTS

The cell nadir of < 100 NC/ microL was reached on Day +4 (BM) and on day 0 (PBSC), when unusual CD34(+) cells of recipient genotype were detected in all patients. They were not clonogenic, showed high CD34 expression, but were negative for CD45, CD38, CD33, CD50, HLA-DR and Stro-1. Between Days +5 and +16, the onset of hematopoietic reconstitution was clearly detectable in multi-parameter evaluation of the FACS data. This was a median of 3.5 days before NC increased above 200/ w L blood and 4-10 days before granulocyte counts were > 500/ microL. It was marked by the appearance of monocytes, immature (CD38(+)) granulocytes, and clonogenic donor CD34(+) cells exhibited normal size and phenotype.

DISCUSSION

We conclude that dynamic FACS analyses can reliably detect hematopoietic reconstitution, but also graft rejection, before a visible increase NC numbers. This may have considerable impact on clinical management strategies.

Death induction by CD99 ligation in TEL/AML1-positive acute lymphoblastic leukemia and normal B cell precursors

Our study was performed to examine the role of CD99 in normal and leukemia BCPs. CD99 is strongly expressed by certain pediatric cancers including BCP-ALL. Modulation of the antigen in ETs and T cells induces apoptosis, hence implicating CD99 as a potential target for anti-cancer therapy. However, nothing is known about these aspects in BCPs. We investigated BCP-ALL cases and normal BCP cells from pediatric BM for CD99 protein and RNA expression as well as for effects of CD99 modulation by mAb. Immunophenotypes, recovery, apoptosis, and aggregation were assessed. Flow cytometry, light microscopy, and qRT-PCR were used in our experiments. An association of CD99 expression levels with the cytogenetic background of pediatric BCP-ALLs was found. Highest CD99 levels were observed in hyperdiploid, followed by TEL/AML1 and random karyotype leukemias. CD99 ligation moderately induced cell death only in TEL/AML1 cases. Stroma cell contact mitigated this effect. Very immature normal BCPs were the most sensitive to CD99-mediated death induction. Type I CD99 mRNA was the main isoform in ALLs and was expressed differentially during BCP maturation. Our data suggest that clinical targeting of CD99 may be effective in BCP-ALL-bearing TEL/AML1 but also may elicit negative effects on normal B-lymphopoiesis. We consider our results as an indication that CD99 may play a physiologic role in the clonal deletion processes necessary for B-lymphoid selection.

Interleukin-3 promotes the expression of E-NPP3/CD203C on human blood basophils in healthy subjects and in patients with birch pollen allergy

We recently identified the ectoenzyme CD203c as a novel basophil activation antigen that is upregulated in response to FcepsilonRI cross-linkage. We investigated the effects of various interleukins (ILs) on expression of CD203c on blood basophils using an antibody against CD203c and flow cytometry. Of all cytokines tested, only IL-3 was found to upregulate expression of CD203c on basophils above baseline levels. The effects of IL-3 were dose- and time-dependent (EC(50): 0.1-1 ng/ml) without differences observed between healthy and allergic donors. Whereas anti-IgE induced maximum upregulation of CD203c within 15 minutes, the IL-3-induced upregulation showed a maximum after 180 minutes. IgE-receptor cross-linking resulted in enhanced expression of both CD63 and CD203c, whereas IL-3 enhanced the levels of CD203c without promoting expression of CD63. The IL-3-induced upregulation of CD203c was also observed in highly enriched basophils and was counteracted by a blocking antibody against the alpha chain of the IL-3 receptor (CD123). The IL-3-induced upregulation of CD203c was also found to depend on the presence of calcium. To analyze signaling pathways involved in IL-3-induced upregulation of CD203c, pharmacologic inhibitors were applied. The PI3-kinase inhibitors, wortmannin and LY294002 counteracted the IL-3-induced expression of CD203c, whereas MEK- and PKC inhibitors showed no effects. In conclusion, IL-3 upregulates expression of CD203c on basophils through a specific receptor and via a PI3-kinase-dependent signaling-pathway. Compared to FcepsilonRI-mediated cell activation, IL-3-induced upregulation of CD203c is a late(r) event and is not accompanied by upregulation of CD63.

Expression of the target receptor CD33 in CD34+/CD38-/CD123+ AML stem cells

BACKGROUND

CD33 (Siglec-3) is becoming increasingly important as a target of antibody-mediated therapy in acute myeloid leukaemia (AML). In normal myelopoiesis, expression of CD33 is restricted to advanced stages of differentiation, whereas primitive stem cells do not express CD33. In the present study, we asked whether leukaemic stem cells in patients with AML express CD33.

MATERIALS AND METHODS

A multicolour-staining technique was applied in 11 patients with AML, and leukaemic progenitors defined as CD34(+)/CD38(-)/CD123(+) cells. AML stem cells were purified by cell sorting and were examined for expression of CD33 mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

In all patients in whom the majority of myeloblasts expressed CD33 (n = 8), AML progenitors reacted with the CD33 antibody P67.6. Repopulation experiments utilizing irradiated NOD/SCID mice confirmed that AML stem cells in these patients reside within the CD33(+) subpopulation of the leukaemic clone. Moreover, highly purified AML stem cells (> 98% purity) from patients with CD33(+) AML were found to express CD33 mRNA in RT-PCR analyses. CD33 was neither detectable on CD34(+)/CD38(-) cells in normal bone marrow nor on leukaemic stem cells in patients with CD33-negative AML.

CONCLUSIONS

Leukaemic stem cells in patients with CD33(+) AML express CD33. This observation is in favour of novel treatment concepts employing CD33-targeting antibodies in AML.

Expression of the putatively regulatory T-cell marker FOXP3 by CD4(+)CD25+ T cells after pediatric hematopoietic stem cell transplantation

FOXP3 has been proposed to be critical for the regulatory function of CD4(+)CD25+ T cells and it has been reported that its expression correlates with protection from graft-versus-host-disease (GvHD) after allogeneic hematopoietic stem cell transplantation (HSCT). Here, by monitoring 28 pediatric HSCT recipients, we found that the levels of FOXP3-mRNA expression in highly enriched CD4(+)CD25+ cells were identical to those in healthy controls irrespective of GvHD status. Moreover, FOXP3-mRNA was abundant in recently in vitro stimulated CD4(+)CD25+ cells that lacked regulatory function. Together these findings suggest that FOXP3-mRNA expression primarily reflects CD4(+)CD25+ cell frequency rather than defining the regulatory potential of CD4(+)CD25+ T cells and GvHD risk after HSCT.

Enumeration and immunohistochemical characterisation of bone marrow basophils in myeloproliferative disorders using the basophil specific monoclonal antibody 2D7

BACKGROUND

Basophils are highly specialised granulocytes that express a unique profile of antigens and increase in myeloproliferative disorders (MPD). In chronic myeloid leukaemia (CML), basophilia is a diagnostic and prognostic determinant. So far, however, no reliable approach for routine detection and enumeration of bone marrow basophils has become available.

OBJECTIVE

To detect and enumerate basophils in bone marrow sections in patients with CML and other MPD.

METHODS

The anti-basophil antibody 2D7 was applied to paraffin embedded bone marrow sections from normal/reactive subjects (n = 31), patients with CML (chronic phase, n = 37; accelerated phase, n = 9), and other MPD (chronic idiopathic myelofibrosis (CIMF), n = 20; polycythaemia vera (PV), n = 20; essential thrombocythaemia (ET), n = 20; indolent systemic mastocytosis (ISM), n = 7).

RESULTS

As assessed by serial section staining, 2D7(+) cells were found to co-express myeloperoxidase, histidine decarboxylase, CD9, and CD43, but did not express B cell or T cell restricted antigens. 2D7(+) bone marrow cells were found to increase in CML compared with normal/reactive bone marrow and other MPD (median numbers of 2D7(+) cells/mm(2): CML, 33; normal/reactive bone marrow, 6; CIMF, 10; PV, 6; ET, 5; ISM, 3; p<0.05). The highest basophil counts were recorded in accelerated phase CML (115/mm(2)).

CONCLUSIONS

A novel immunohistochemical procedure has been established for basophil detection in normal bone marrow and MPD. This approach should help in the quantification of bone marrow basophils at diagnosis and during anti-leukaemic treatment.

Detection of differentiation- and activation-linked cell surface antigens on cultured mast cell progenitors

BACKGROUND

Mast cells (MC) are multifunctional effector cells of the immune system. They derive from uncommitted CD34(+) hemopoietic progenitor cells (HPC). Depending on the stage of maturation and the environment, MC variably express differentiation- and activation-linked antigens. Little is known, however, about the regulation of expression of such antigens in immature human MC.

METHODS

We analyzed expression of CD antigens on human MC grown from cord blood-derived CD34(+) HPC. The HPC were isolated by magnetic cell sorting (MACS) and FACS to >97% purity, and were cultured in stem cell factor (SCF) and interleukin (IL)-6 with or without additional cytokines (IL-4 or IL-10) in serum-free medium. The cell surface phenotype of MC was determined by monoclonal antibodies and flow cytometry.

RESULTS

Cultured MC progenitors were found to react with antibodies against various CD antigens including CD58, CD63, CD117, CD147, CD151, CD203c, and CD172a, independent of the growth factors used and time-point investigated (days 14-42). CD116 [granulocyte-macrophage colony-stimulating factor receptor alpha (GM-CSFRalpha)] and CD123 (IL-3Ralpha) were expressed on MC precursors on day 14, but disappeared thereafter. Cultured MC did not express CD2, CD3, CD5, CD10, CD19, or CD25. Addition of IL-10 to MC cultures showed no effect on expression of CD antigens. However, IL-4 was found to promote expression of CD35 and CD88 on cultured MC without changing expression of other CD antigens.

CONCLUSIONS

Most MC antigens may already be expressed at an early stage of mastopoiesis. Whereas IL-3R and GM-CSFRs are lost during differentiation of MC, these cells may acquire complement receptors (CD35, CD88) under the influence of distinct cytokines.

Evaluation of normal and neoplastic human mast cells for expression of CD172a (SIRPα), CD47, and SHP-1

Signal regulatory proteins (SIRPs) and tyrosine phosphatases have recently been implicated in the control of receptor tyrosine kinase (RTK)-dependent cell growth. In systemic mastocytosis (SM), neoplastic cells are driven by the RTK KIT, which is mutated at codon 816 in most patients. We examined expression of SIRPalpha, SIRPalpha ligand CD47, and Src homology 2 domain-containing protein tyrosine phosphatase-1 (SHP-1), a tyrosine phosphatase-type, negative regulator of KIT-dependent signaling, in normal human lung mast cells (HLMC) and neoplastic MC obtained from nine patients with SM. As assessed by multicolor flow cytometry, normal LMC expressed SIRPalpha, CD47, and SHP-1. In patients with SM, MC also reacted with antibodies against SIRPalpha and CD47. By contrast, the levels of SHP-1 were low or undetectable in MC in most cases. Corresponding data were obtained from mRNA analysis. In fact, whereas SIRPalpha mRNA and CD47 mRNA were detected in all samples, the levels of SHP-1 mRNA varied among donors. To demonstrate adhesive functions for SIRPalpha and CD47 on neoplastic MC, an adhesion assay was applied using the MC leukemia cell line HMC-1, which was found to bind to immobilized extracellular domains of SIRPalpha1 (SIRPalpha1ex) and CD47 (CD47ex), and binding of these cells to CD47ex was inhibited by the CD172 antibody SE5A5. In summary, our data show that MC express functional SIRPalpha and CD47 in SM, whereas expression of SHP-1 varies among donors and is low compared with LMC. It is hypothesized that CD172 and CD47 contribute to MC clustering and that the "lack" of SHP-1 in MC may facilitate KIT-dependent signaling in a subgroup of patients.

CD25 Indicates the Neoplastic Phenotype of Mast Cells

The diagnosis of systemic mastocytosis (SM) is based primarily on the histologic and immunohistochemical evaluation of a bone marrow trephine biopsy specimen. Although mast cell (MC) specific antigens like tryptase and chymase are detectable in routinely processed tissue, no immunohistochemical markers that can be used to discriminate between normal and neoplastic MCs are yet available. We have investigated the diagnostic value of an antibody against CD25 for the immunohistochemical detection of MCs in bone marrow sections in 73 patients with SM and 75 control cases (reactive marrow, n = 54; myelogenous neoplasms, n = 21) and correlated the results with the presence of c-kit mutations. While MCs in almost all patients with SM (72 of 73) expressed CD25, none of the control samples contained CD25-positive MCs. Irrespective of the SM subtype, most of neoplastic MCs expressed CD25. In 3 patients with advanced MC disease, pure populations of neoplastic MCs were obtained and found to express CD25 mRNA by RT-PCR analysis. In addition, all patients with CD25-positive MCs contained c-kit mutations, while all control cases exhibited wild type c-kit. CD25 therefore appears to be a reliable immunohistochemical marker for the discrimination of neoplastic from normal/reactive MCs, with potential as a diagnostic tool in SM.

Identification of heme oxygenase-1 as a novel BCR/ABL-dependent survival factor in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a stem cell disease in which BCR/ABL promotes the survival of leukemic cells. Heme oxygenase-1 (HO-1) is an inducible stress protein that catalyzes the degradation of heme and has recently been implicated in the regulation of growth and survival of various neoplastic cells. In the present study, we analyzed the expression and role of HO-1 in CML cells. As assessed by Northern and Western blot analysis as well as immunostaining, primary CML cells were found to express HO-1 mRNA and the HO-1 protein in a constitutive manner. Exposure of these cells to the BCR/ABL tyrosine kinase inhibitor STI571 resulted in decreased expression of HO-1 mRNA and protein. In addition, BCR/ABL was found to up-regulate HO-1 promoter activity, mRNA levels, and protein levels in Ba/F3 cells. To investigate the role of HO-1 for survival of primary CML cells, the HO-1 inducer hemin was used. Hemin-induced expression of HO-1 was found to protect CML cells from STI571-induced cell death. In addition, inhibition of HO-1 by zinc-(II)-deuteroporphyrin-IX-2,4-bisethyleneglycol resulted in a substantial decrease of cell viability. Furthermore, overexpression of HO-1 in the CML-derived cell line K562 was found to counteract STI571-induced apoptosis. Together, our data identify HO-1 as a novel BCR/ABL-driven survival molecule and potential target in leukemic cells in patients with CML. The pathogenetic and clinical implications of this observation remain to be elucidated.

CD99 expression in T-lineage ALL: implications for flow cytometric detection of minimal residual disease

Expression of CD99 is higher on immature than on mature T cells. We postulated that this marker could be used to assess minimal residual disease (MRD) in T-lineage acute lymphoblastic leukemia (T-ALL). In diagnostic bone marrow (BM) samples from 27 children with T-ALL, expression of CD99 on leukemic lymphoblasts by flow cytometry was in median 7.7 times higher than on normal T lymphocytes from within the same sample. In 85% of cases, leukemic MFI values were higher than the mean MFI+2 s.d. of normal populations. We applied CD99 to study MRD in 39 follow-up samples from 15 consecutive T-ALL patients, and compared the results with those obtained with the well-established MRD-marker terminal deoxynucleotidyl transferase (TdT). Either antibody was combined in four-color flow cytometry with CD7, surfaceCD3, and cytoplasmicCD3. We found that CD99 was a valid complement to TdT in quantifying T-ALL MRD. Given a considerable interpatient variability, CD99 could be favorably used in nine patients, and TdT in other five patients. Both approaches showed a similar very low nonspecific background throughout 12 weeks from diagnosis (in median 0.002% of nucleated BM cells in patients with non-T ALL). We conclude that CD99 is a highly informative tool for MRD detection in T-ALL, bearing the advantage of surface expression in contrast to TdT.

Lineage-specific chimaerism after stem cell transplantation in children following reduced intensity conditioning: potential predictive value of NK cell chimaerism for late graft rejection

Chimaerism of FACS-sorted leucocyte subsets (CD14+, CD15+, CD3-/56+, CD3+/4+, CD3+/8+, CD19+) was monitored prospectively between days +14 and +100 in 39 children undergoing allogeneic stem cell transplantation with reduced intensity-conditioning regimens. Cell subsets exceeding 1% of nucleated cells were subject to cell sorting. Chimaerism was analysed by dual-colour FISH and/or by short tandem repeat-polymerase chain reaction. The chimaerism pattern on day +28 was evaluated with regard to its correlation with graft rejection. Of 39 patients, nine patients had donor chimaerism (DC) in all subsets. Mixed/recipient chimaerism (MC/RC) was detectable within T cells in 62%, within NK cells in 39% and within monocytes and granulocytes in 38% of the patients. The correlation of secondary graft rejection with the chimaerism pattern on day +28 revealed the strongest association between RC in NK-cells (P<0.0001), followed by T cells (P=0.001), and granulocytes and monocytes (P=0.034). Notably, patients with RC in T cells rejected their graft only if MC or RC was also present in the NK-cell subset. By contrast, none of the children with DC in NK cells experienced a graft rejection. These observations suggest that, in the presence of recipient T-cell chimaerism, the chimaerism status in NK-cells on day +28 might be able to identify patients at high risk for late graft rejection.

Response of Ewing tumor cells to forced and activated p53 expression

The EWS-FLI1 transcription factor is consistently expressed in 85% of Ewing tumors (EFT). In heterologous cells, EWS-FLI1 induces p53-dependent cell cycle arrest or apoptosis. It has been speculated that the p53 tumor suppressor pathway may be generally compromised in EFT despite only rare p53 mutations. In order to test for functional integrity of this pathway, we have investigated a series of EFT cell lines that differ from each other with respect to their endogenous p53 and INK4A gene status for their response to ectopic p53 expression and to stimulation of endogenous p53 activity by X-ray treatment. Significant interindividual and intratumoral variations in the apoptotic propensity of EFT cell lines to transient expression of ectopic p53 were observed, which was independent of the level of p53 expression. In cell lines with a low apoptotic incidence, apoptosis was delayed and the surviving fraction showed a prolonged growth arrest. Complete resistance to p53-induced apoptosis in two cell lines established from the same patient was associated with a high BCL2/BAX ratio and low levels of APAF1. Sensitivity to X-rays showed a trend towards a higher apoptotic rate in wild-type (wt) p53 expressing than in p53 mutant cells. However, one wt p53-expressing EFT cell line was completely refractory to irradiation-stimulated cell death despite high apoptotic responsiveness to ectopic p53. No difference in Ser15 phosphorylation and the transcriptional activation of p53 targets was observed in wt p53 EFT cell lines irrespective of the induction of cell death or growth arrest. All together, our results demonstrate that despite significant variability in the outcome, cell death or cell cycle arrest, the p53 downstream pathway and the DNA damage signaling pathway are functionally intact in EFT.

Comparison of p53 mutational status with mRNA and protein expression in a panel of 24 human breast carcinoma cell lines

We analyzed the p53 mutational status, mRNA and protein expression in 24 human breast carcinoma cell lines. Following measurement of their DNA content with flow cytometry, we ascertained the copy numbers of the centromere of chromosome 17 (cen17) and p53 with fluorescence in situ hybridization (FISH). A functional yeast assay (FASAY) was used to screen for inactivating mutations. Positive results were subsequently verified by DNA sequencing. Finally, we assessed the mRNA expression with a competitive reverse transcription-polymerase chain reaction (RT-PCR) assay and the protein expression with immunocytochemical staining, western blot, and quantitative flow cytometry. The DNA content of the cell lines ranged from 0.85 to 2.58. Nine cell lines had concordant copy numbers (between two and four) of p53 and cen17, whereas 12 had more, and three less cen17 than p53 copies. The FASAY was successful in all but one cell line and revealed the presence of mutated alleles in 16 of them, 13 cell lines expressed only the mutated, and three both the mutated and the wild-type alleles. The mutations were comprised of 11 missense, two nonsense, and three frameshift mutations. Immunocytochemical staining, western blot and quantitative flow cytometry yielded comparable p53 protein expression results. However, both the mRNA and the protein expression levels varied considerably in the different cell lines and no consistent pattern with regard to the respective p53 mutational status became evident. The results obtained in these breast carcinoma cell lines indicate that no clear-cut linear relationship exists between the p53 mutational status and the extent of its respective mRNA and protein expression. Therefore, direct DNA analyses and functional assays remain the only methods for the reliable detection of p53 mutations.

Improved flow cytometric method to enumerate residual cells: minimal linear detection limits for platelets, erythrocytes, and leukocytes

Increasing demand for quality control of blood products requires more sensitive methods to enumerate residual cells. Presently, the reported threshold (in cells per microliter) is 400 for red blood cells, 30-500 for platelets, and 1 for leukocytes. To examine precision and linearity in enumerating residual platelets and red blood cells, EDTA-anticoagulated blood from healthy donors was serially diluted with serum, stained in TruCount tubes using a no-lyse/no-wash procedure and a monoclonal antibody cocktail against the CD42a (FL1) and glycophorin-A (FL2) epitopes, and analyzed by flow cytometry. Leukocyte counts were determined in separate tubes. Cell preparation and analysis were performed once for 20 blood samples each and 20 times using the same specimen. Acquisition from the same tube was performed separately for platelets (threshold on FL1) and red blood cells (threshold on FL2). Multiparameter analysis was used for data evaluation. Linear results were obtained for platelets per microliter between 3,410 and 5 and for red blood cells per microliter between 54,000 and 3. For the lower cell concentrations, the coefficient of variation was 16.7% for platelets and 10.9% for red blood cells. The presented method allows the distinction between physiologically intact and ghost red blood cells. The method represents a reliable, sensitive, and accurate approach to quantify platelets and red blood cells in diluted blood. It can be applied to enumerate residual cells in plasma products and meets the increasing demand for quality control in blood components.

C5a stimulates production of plasminogen activator inhibitor-1 in human mast cells and basophils

We have recently shown that resting human mast cells (MCs) produce tissue-type plasminogen activator (t-PA) without simultaneously expressing plasminogen activator inhibitor 1 (PAI-1). In the present study we have identified the anaphylatoxin rhC5a as a potent inducer of PAI-1 expression in human MCs and basophils. In primary human skin MCs and primary blood basophils, exposure to rhC5a was followed by an increase from undetectable to significant levels of PAI-1. In addition, rhC5a induced a concentration- and time-dependent increase in PAI-1 antigen in the MC line HMC-1 and the basophil cell line KU-812 and increased the expression of PAI-1 mRNA in HMC-1. In conditioned media of HMC-1 treated with rhC5a, active PAI-1 could be detected. A simultaneous loss of t-PA activity in conditioned media from the same cells indicated that rhC5a-induced PAI-1 was capable of inhibiting the enzymatic activity of coproduced t-PA. Correspondingly, the levels of t-PA-PAI-1 complexes increased in rhC5a-treated cells. When HMC-1 cells were incubated with pertussis toxin or anti-C5a receptor antibodies, the effect of rhC5a on PAI-1 production was completely abolished. Treatment of C5a with plasmin resulted in loss of its ability to induce PAI-1 production in MCs. Considering the suggested role for MCs and components of the complement system in the development of cardiovascular diseases, we hypothesize that MCs, by producing t-PA in a resting state and by expressing PAI-1 when activated by C5a, might participate in the modulation of the balance between proteases and protease inhibitors regulating tissue injury and repair in such disease processes.

Collection efficiencies of MNC subpopulations during autologous CD34+ peripheral blood progenitor cell (PBPC) harvests in small children and adolescents

There is increasing demand for mononuclear cell (MNC) harvests not only for PBPC but also for immune therapies using dendritic cells and donor lymphocytes. We determined the collection efficiencies (CE) of various MNC subpopulations during CD34+ cell harvests using a Fenwal CS 3000 Plus Omnix system in small children and adolescents. The cell content of 140 leukapheresis products (LP) was prospectively evaluated in 45 pretreated patients with solid tumors and hematological malignancies. The median age was 12 years (range 0.8-22), and the median body weight (BW) 43 kg (range 9-92). Depending upon the BW of the patients, the media used for priming were saline (SP) in 86, human albumin (HA, HAP) in 10, and packed red blood cells (BP) in 44 apheresis procedures. The major nucleated cell (NC) fractions collected were monocytes (52% of NC) and CD3+ T cells (26%). The median cell yield for monocytes was 174 * 10(6)/kg (range 24-613) representing a CE of 55%. The median number of CD3(+) T cells was 84 * 10(6)/kg (range 5.6-380; CE = 74%). CD34+ cells represented a very small cell fraction of the LP (1.3% of NC), with a median yield of 4.2 * 10(6)/kg (range 0.2-87) and a CE of 63%. The cell yield of various MNCs was significantly correlated with the cell count in the peripheral blood (PB) and with the blood volume processed (ANOVA, P < 0.0001). No influence on the CE was observed for the priming procedure, the patients' age or sex, or the other adaptations used in the harvesting protocol. In conclusion, the Fenwal CS 3000 Plus OMNIX system with the CD34+ cell program and the described adaptations, is also predictably useful for harvest of monocytes or lymphocytes in pediatric patients. We present regression equations that predict the cell yield of various MNC subpopulations in apheresis products.

Prognostic significance and modalities of flow cytometric minimal residual disease detection in childhood acute lymphoblastic leukemia

Detection of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL) predicts outcome. Previous studies were invariably based on relative quantification and did not investigate sample-inherent parameters that influence test accuracy, which makes comparisons and clinical conclusions cumbersome. Hence, we conducted a prospective, population-based MRD study in 108 sequentially recruited children with ALL uniformly treated with the ALL-Berlin-Frankfurt-Münster (ALL-BFM) 95 protocol in Austria (median follow-up of 40 months). Using sensitive, limited antibody panel flow cytometry applicable to 97% of patients, we investigated 329 bone marrow samples from 4 treatment time points. MRD was quantified by blast percentages among nucleated cells (NCs) and by absolute counts (per microliter). Covariables such as NC count, normal B cells, and an estimate of the test sensitivity were also recorded. Presence and distinct levels of MRD correlated with a high probability of early relapse at each of the time points studied. Sequential monitoring at day 33 and week 12 was most useful for predicting outcome independently from clinical risk groups: patients with persistent disease (> or =1 blast/microL) had a 100% probability of relapse, compared to 6% in all others. Absolute MRD quantification was more appropriate than relative, due to considerable variations in total NC counts between samples. Regeneration of normal immature B cells after periods of rest from treatment limited the test sensitivity. In conclusion, MRD detection by flow cytometry is a strong and independent outcome indicator in childhood ALL. Standardization regarding absolute quantification on the basis of NCs and assessment during periods of continuous treatment promise to increase the accuracy, simplicity, and cost efficiency of the approach.

Expression, epitope analysis, and functional role of the LFA-2 antigen detectable on neoplastic mast cells

Recent data suggest that mast cells (MCs) in patients with systemic mastocytosis or mast cell leukemia express a CD2-reactive antigen. To explore the biochemical nature and function of this antigen, primary MCs as well as the MC line HMC-1 derived from a patient with mast cell leukemia were examined. Northern blot experiments revealed expression of CD2 messenger RNA in HMC-1, whereas primary nonneoplastic MCs did not express transcripts for CD2. In cell surface staining experiments, bone marrow (BM) MCs in systemic mastocytosis (n = 12) as well as HMC-1 cells (30%-80%) were found to express the T11-1 and T11-2 (but not T11-3) epitopes of CD2. By contrast, BM MCs in myelodysplastic syndromes and nonhematologic disorders (bronchiogenic carcinoma, foreskin phimosis, uterine myeomata ) were consistently CD2(-). All MC species analyzed including HMC-1 were found to express LFA-3 (CD58), the natural ligand of CD2. To study the functional role of CD2 on neoplastic MCs, CD2(+) and CD2(-) HMC-1 cells were separated by cell sorting. CD2(+) HMC-1 cells were found to form spontaneous aggregates and rosettes with sheep erythrocytes in excess over CD2(-) cells, and a T11-1 antibody inhibited both the aggregation and rosette formation. Moreover, exposure of CD2(+) HMC-1 cells to T11-1 or T11-2 antibody was followed by expression of T11-3. In addition, stimulation of neoplastic MCs through T11-3 and a second CD2 epitope resulted in histamine release. These data show that neoplastic MCs express functionally active CD2. It is hypothesized that expression of CD2 is associated with pathologic accumulation and function of MCs in systemic mastocytosis.

Functional maturation of dendritic cells by exposure to CD40L transgenic tumor cells, fibroblasts or keratinocytes

Tumor antigen pulsed dendritic cells (DCs) can induce anti-tumor immunity. We studied strategies for the reliable generation of such a tumor vaccine by functional maturation of DCs via interaction of CD40 with its ligand (CD40L, CD154). Exposure of immature DCs to CD40L transgenic cells, soluble recombinant human CD40L molecules or lipopolysaccharide induced expression of the co-stimulatory molecules, CD80 and CD86, and supported an allogeneic mixed leukocyte reaction. In contrast, the release of IL-12, an important mediator of anti-tumor immunity, and antigen-specific expansion and IFNgamma secretion of lymphocytes, was strongly triggered only by DCs exposed to CD40L transgenic cells.

Characterization of distinct consecutive phases in non-genotoxic p53-induced apoptosis of Ewing tumor cells and the rate-limiting role of caspase 8

To dissect the p53-dependent apoptotic pathway, events following induction of temperature sensitive (ts) p53val138 were studied in a Ewing tumor cell line. Transcriptional deregulation of p53 targets first observable after 1 h at 32 degrees C preceded activation of caspases and the break-down of mitochondrial respiratory activity. Activation of caspases was first observed 4 h after p53 induction. Using peptide inhibitors we identified activation of caspase 8 upstream of caspases-9 and -3. Although the caspase 8 specific inhibitor z-IETD.fmk did not affect translocation of BAX to the mitochondrial membrane and cytochrome C release it almost completely blocked cleavage of the prototype caspase substrate PARP and DNA fragmentation while enforcing mitochondrial depolarization and production of reactive oxygene species (ROS). Activation of caspase 8 did not involve death-domain receptor signaling. Expression of BCL2 only partially suppressed caspase activation but blocked apoptosis. Replacement of the N-terminus of p53val138 by the related VP16 transactivation domain created a ts p53 with a tanscriptional activity indistinguishable from p53val138 until the time of caspase activation. However, the VP16 - p53 fusion failed to trigger caspases and subsequent induction of the ROS producing gene pig3 paralleled by complete loss of apoptotic activity. These results indicate that p53-dependent transcriptional deregulation, triggering of the caspase cascade and the mitochondrial break-down occur in a timely ordered sequence coordinated by the genuine p53 amino terminus and suggest caspase 8 and PIG3 as key regulatory elements in this process. Oncogene (2000) 19, 4096 - 4107

Increased baseline occupancy of D2 receptors by dopamine in schizophrenia

The classical dopamine hypothesis of schizophrenia postulates a hyperactivity of dopaminergic transmission at the D(2) receptor. We measured in vivo occupancy of striatal D(2) receptors by dopamine in 18 untreated patients with schizophrenia and 18 matched controls, by comparing D(2) receptor availability before and during pharmacologically induced acute dopamine depletion. Acute depletion of intrasynaptic dopamine resulted in a larger increase in D(2) receptor availability in patients with schizophrenia (19% +/- 11%) compared with control subjects (9% +/- 7%, P = 0.003). The increased occupancy of D(2) receptors by dopamine occurred both in first-episode neuroleptic-naive patients and in previously treated chronic patients experiencing an episode of illness exacerbation. In addition, elevated synaptic dopamine was predictive of good treatment response of positive symptoms to antipsychotic drugs. This finding provides direct evidence of increased stimulation of D(2) receptors by dopamine in schizophrenia, consistent with increased phasic activity of dopaminergic neurons.

Relation of familial schizophrenia to negative symptoms but not to the deficit syndrome

OBJECTIVE

Although a family history of schizophrenia has been associated with negative symptoms, family history is inconsistently related to the presence of the deficit syndrome.

METHOD

The authors assessed family history and the deficit syndrome in 99 patients with DSM-III-R-diagnosed schizophrenia who were assessed during clinical treatment. Of these 99 patients, 45 were assessed both while antipsychotic free and during antipsychotic treatment to index their treatment response.

RESULTS

Patients with (N=39) and without (N=60) a family history of schizophrenia had similar proportions of the deficit syndrome. Yet family history and deficit syndrome categorizations identified a group with greater negative symptoms on the Positive and Negative Syndrome Scale. Those with a family history had greater emotional withdrawal, poor rapport, and lack of spontaneity. Groups with and without the deficit syndrome similarly differed in these symptoms but also in affective blunting, motor retardation, and passive or apathetic social withdrawal. The study involving antipsychotic-free and antipsychotic treatment phases showed main medication effects explaining positive, psychopathology, depression, and activation symptoms but not negative symptoms. Only patients without a family history had improved negative symptoms with antipsychotic treatment.

CONCLUSIONS

Patients with a family history of schizophrenia had greater and more treatment-resistant negative symptoms than those without a family history. They were not more likely to have the deficit syndrome. The group with a family history had more pathology only in negative symptoms related to psychosocial function. The stable negative symptoms specifically related to the genetic vulnerability to inherit schizophrenia might be those associated with psychosocial functioning.

Kinetics of chimerism during the early post-transplant period in pediatric patients with malignant and non-malignant hematologic disorders: implications for timely detection of engraftment, graft failure and rejection

The monitoring of chimerism by PCR has become a routine diagnostic approach in patients after allogeneic bone marrow or peripheral blood stem cell transplantation. Nevertheless, a temporal correlation between molecular and hematologic assessment of engraftment has not been clearly established. To address this issue, and to determine the potential clinical implications of early kinetics of mixed chimerism, we have investigated 66 allogeneic stem cell transplantations (SCTs) in 58 pediatric patients suffering from different types of leukemia (n = 44) or non-malignant hematologic disorders (n = 14) by close molecular monitoring during the first days and weeks after transplantation. Patient- and donor-derived hematopoiesis were assessed at 1- to 3-day intervals in peripheral blood samples by PCR analysis of highly polymorphic microsatellite loci (STR-PCR). Detection of an increasing, and ultimately dominant donor-specific allelic pattern, which we defined as molecular engraftment, preceded hematologic engraftment by a median of 7 days (range 1-17 days) in all patients investigated. PCR analyses during the first days after transplantation facilitated detection of molecular engraftment according to the above definition by day +14 (range day +2 to day +14), thus permitting prediction of successful engraftment (upper limit of the two-sided confidence interval po = 6%) while the peripheral leukocyte counts were mostly below 200/microl. In three cases, however, the criteria for molecular engraftment were not fulfilled by day +14. These patients also failed to show hematologic engraftment, and required a second transplantation. Close monitoring by STR-PCR showed that graft rejection and autologous recovery can occur early and with very rapid dynamics. Molecular analysis of specific leukocyte subsets isolated by flow-sorting enabled sensitive assessment of changes in the pattern of chimerism which had escaped detection in assays using whole white blood cell (WBC) samples. This approach facilitated the identification of expanding or decreasing recipient cells, and permitted early detection of impending rejection or relapse. Moreover, monitoring of the dynamics of chimerism allowed rapid assessment of the response to therapy. Our observations provide support for the concept of initiating genotype analyses early after SCT and monitoring at rather short intervals to permit timely evaluation of clinically relevant processes, and to provide a basis for early implementation of treatment.

SPECT study of visual fixation in schizophrenia and comparison subjects

BACKGROUND

The consistent association of impaired eye movements and schizophrenia suggests a relationship between the neurobiology of the illness and visual pursuit systems. Visual fixation (VF), an eye "movement" task at zero velocity, is the simplest such abnormality in schizophrenia patients and their relatives.

METHODS

We used a VF task for a functional imaging study. Six neuroleptic-free schizophrenia patients and eight gender and mean age matched comparison subjects had SPECT scans with 20 mCi of Tc99-HMPAO, during VF on a simple blue line intersection. MEDX data saved in ANALYZE format for SPM 95 was used to generate paired t-test statistical data for display in Talairach space, with rCBF changes given as Z-scores.

RESULTS

Patients, compared to controls, had increased rCBF in both the parahippocampal gyrus (bilaterally) and in the right fusiform gyrus. They had decreased rCBF in the left frontal cortex, including medial and superior frontal gyri and anterior cingulate. Overall, compared to controls, patients had medial temporal lobe hyperperfusion along with left prefrontal hypoperfusion.

CONCLUSIONS

These findings are consistent with the hypothesized imbalance between the medial temporal and frontal lobes that is postulated for schizophrenia. It was of interest that the relative rCBF differences between schizophrenia patients and controls in this small sample were observable with this cognitively non-demanding visual fixation task.

CD99 (MIC2) expression in paediatric B-lineage leukaemia/lymphoma reflects maturation-associated patterns of normal B-lymphopoiesis

We have recently shown that CD99 (MIC2) is differentially expressed during normal early B-cell development in the bone marrow (BM). Since immature B-cell precursors (BCP) are assumed to correspond to some extent to acute lymphoblastic leukaemia (ALL) and non-Hodgkin's lymphoma (NHL) cells with respect to patterns of phenotypic differentiation, we wondered whether the particular maturation-associated expression patterns of CD99 in the normal BCP stages were conserved also in malignant cells. Therefore we compared malignant and physiological B cells from paediatric ALL/NHL and normal BM samples with respect to CD99 expression using selective gating and semi-quantitative flow cytometry. Common-ALLs (n = 45) were similar to their corresponding, very immature BCPs (stage 1) in expressing very high levels of CD99. Most pre-B ALLs (n = 16) were also CD99hi and thus differed from the patterns found in normal cytoplasmic mu-chain+ (cmu+) pre-B cells (stage 2, CD99lo). In particular, we found that those pre-B-ALL cases which were CD34+ also showed higher CD99 expression than the CD34- cases. This prompted us to investigate the levels of CD99 in those rare normal BCPs which also coexpress CD34 and cmu; these cells, which are transitory from stage 1 to stage 2, were found also CD99hi, thus precisely reflecting the patterns of CD34+ pre-B ALLs. The blasts of Burkitt-type B-cell ALL/NHL samples (n = 13) expressed considerably less CD99, similarly to the more differentiated BCP stages 2 (cmu+) and 3 (surface mu-chain+). In summary, we found that paediatric B-lineage malignancies display remarkable synchrony regarding the levels of CD99 expression compared to their putative normal counterparts.

Skin-associated lymphocytes in the peripheral blood of patients with atopic dermatitis: signs of subset expansion and stimulation

BACKGROUND

Skin-associated T cells are defined by the cutaneous lymphocyte-associated antigen (CLA). In atopic dermatitis (AD), CLA+ T cells harbor allergen-reactive memory cells, spontaneously secrete TH2 cytokines, and display signs of increased in vivo activation, thus relating the subset to the central disease pathomechanisms.

OBJECTIVES

It is not known whether the proportion of circulating CLA+ T cells might be expanded in AD. We were therefore prompted to compare the peripheral blood lymphocyte subpopulations of patients with AD with those of control subjects.

METHODS

We used 3-color flow cytometry to investigate age-matched peripheral blood samples of pediatric and young adult patients with mild (n = 21) or severe (n = 15) AD, patients with allergic/atopic diseases not involving the skin (n = 9), and healthy control subjects (n = 14).

RESULTS

We found no differences among the study groups with respect to the general proportions of T cells, CD4(+) T cells, CD8(+) T cells, B cells, NK cells, CD103(+) T cells, and CD25(+) T cells among total circulating lymphocytes. However, there were slightly more CD4(+) memory cells and clearly more HLA-DR+ T cells in patients with severe AD. Most remarkably, patients with severe AD had a significantly expanded proportion of CLA+ T cells (P =.024) and CLA+/CD4(+) T cells (P =.006) but similar proportions of CLA+/CD8(+) T cells compared with control subjects. Patients with severe AD also had distinctly more HLA-DR+/CLA+ T cells than control subjects (P =. 005). Similar alterations were seen in patients with mild AD, but these were not statistically significant. After correction for age, all differences were significant only in probands less than 10 years of age.

CONCLUSIONS

Circulating skin-associated T cells (CLA+) show signs of subset expansion and enhanced activation in patients with AD. These alterations, compared with control values, affect CD4(+) memory T cells in particular and are prominent only in children less than 10 years of age.

Detection of residual disease in pediatric B-cell precursor acute lymphoblastic leukemia by comparative phenotype mapping: a study of five cases controlled by genetic methods

We recently investigated samples of pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL) and normal bone marrow (BM). We found that leukemic blasts, compared to their physiologic counterpart cells, frequently display aberrant phenotypes with respect to levels of expression of certain antigens. Using multiparameter flow cytometry, these differences enabled us to trace leukemic cells admixed to normal BM, which suggested that this approach might be a useful strategy for minimal residual disease detection. In the present study, we used the same multiparameter approach ("comparative phenotype mapping") to prove that such quantitative phenotypic differences really exist between malignant and normal BCP when simultaneously present in the BM. We demonstrate this by five exemplary follow-up BM samples from patients with BCP-ALL, all of which showed phenotypically aberrant cells according to levels of expression of CD10, CD11a, CD19, CD34, CD44, or CD45RA, as well as according to altered orthogonal light scattering properties. We confirmed the leukemic nature of these cells by polymerase chain reaction-based detection of bcr1/abl transcripts, and of leukemia clone-specific immunoglobulin heavy chain rearrangements in only the suspicious cells when sorted by flow cytometry, but not in normal BCP or non-B cells. Comparative phenotype mapping thus allows one to distinguish between normal and leukemic cells, and we show that it may enable rapid, specific, and quantitative detection of residual/resurgent leukemia in BCP-ALL.

G-CSF versus GM-CSF for stimulation of peripheral blood progenitor cells (PBPC) and leukocytes in healthy volunteers: comparison of efficacy and tolerability

This study compared two recombinant human (rh) hematopoietic growth factors in healthy volunteers for stem cell stimulation. Granulocyte colony-stimulating factor (G-CSF, n=9) or granulocyte-macrophage colony-stimulating factor (GM-CSF, n=8) was given subcutaneously for 5 days (5 microg/kg/day). Controls (n=5) received no growth factor. Laboratory parameters and side effects were monitored for 8 days. Within 24 h, both cytokines led to a rapid increase of leukocytes, the majority of which were granulocytes. Compared with the controls (n=5), the increase on day 5 in the G-CSF/GM-CSF groups was 37-/10-fold (CD34+ cells), 5.2-/2.4-fold (leukocytes), 7.2-/3.0-fold (granulocytes), 7.4-/4.4-fold (monocytes), 1.7-/1.1-fold (lymphocytes), 9.8-/2.7-fold (basophils), 2.3-/9.6-fold (eosinophils), and 1.9-/1.6-fold (reticulocytes). The mobilization of myeloblasts, promyelocytes, myelocytes, and metamyelocytes coincided with the pronounced increase of CD34 + PBPC observed on day 4. Serum levels of uric acid (UA) and lactic dehydrogenase (LDH) increased under G-CSF, and platelets decreased after G-CSF discontinuation. Rash at the injection site occurred in 50% of the GM-CSF-treated volunteers. Seven volunteers in the GM-CSF group and six in the G-CSF cohort complained of flu-like symptoms, including musculoskeletal pain. We conclude that, in terms of tolerance and mobilization of CD34+ cells and leukocytes, G-CSF is superior to GM-CSF, but higher levels of UA and LDH and late decrease in platelets make monitoring of these parameters necessary.

Four-color flow cytometric investigation of terminal deoxynucleotidyl transferase-positive lymphoid precursors in pediatric bone marrow: CD79a expression precedes CD19 in early B-cell ontogeny

Terminal deoxynucleotidyl transferase (TdT)-positive cells in human bone marrow (BM) are a phenotypically inhomogeneous population of precursor cells. In their majority, these TdT+ cells are unambiguously committed to the B lineage, as evidenced by CD19 expression. However, TdT+ precursors that lack CD19 also exist and these may encompass a differentiation potential for the B as well as for other lineages. Because recent data suggested that CD19 expression is not the earliest differentiation event in B-cell ontogeny, we sought to reevaluate TdT+ lymphoid precursors in pediatric BM to define the phenotypic denominator of B-lineage affiliation upstream of CD19. Using four-color flow cytometry, we focused on the assessment of the CD79a antigen, which is highly B-cell specific and which may also be expressed very early in B-cell ontogeny. We found that a majority of TdT+ cells coexpressed CD19 and CD79a in addition to CD10 and CD34, whereas, in all investigated samples, some TdT+ precursors lacked CD19 but expressed CD79a, which suggestively indicates also their B-lineage affiliation. In contrast to the CD19(+) precursors, which were usually CD10(hi) and CD79b+, these CD19(-)CD79a+ putative B-cell precursors preferentially expressed CD10 at low levels and were CD79b+ in only 41%. About 17% of these TdT+CD19(-)CD79a+ precursors also coexpressed CD33 and CD7, but not myeloperoxidase, CD14, or cytoplasmic CD3, which is discussed in the light of cellular activation rather than lineage promiscuity. Our data confirm that the earliest differentiation stages of B cells can be dissected upon expression of the lineage antigens CD79a and CD19 and imply that CD79a is earlier expressed than CD19. This raises the chance to follow the sequential events heralding B-cell commitment in the most immature precursors by correlating phenotypic and genetic differentiation markers.

Comparative phenotype mapping of normal vs. malignant pediatric B-lymphopoiesis unveils leukemia-associated aberrations

Leukemic cells of B-lineage acute lymphoblastic leukemia (ALL) are regarded as the malignant counterparts of immature, physiologic B cell precursors (BCPs). To determine whether phenotypic differences exist between these corresponding cell types, we investigated samples of normal pediatric bone marrow (n=30) as well as of B-precursor ALL at diagnosis (n=53; common and pre-B subtype). Using three-color multiparameter flow cytometric analysis, we compared the leukemic populations with the physiologic BCPs of corresponding maturity with respect to the intensity with which they expressed a series of antigens. In some of these antigens, leukemia-associated aberrations were frequently observed. In particular, overexpression of CD10 was displayed by 65% of ALL samples, whereas 58% of leukemic cases aberrantly exhibited very low or no CD45RA expression. Regarding CD11a and CD44, 47% and 35% of ALL populations were aberrant as defined by either the absence or significant overexpression of the antigen. In contrast, antigen densities of CD49d, CD49e, and CD99 on leukemic cells were in the normal range of values for BCPs. Combining the patterns of frequently aberrant markers in a comprehensive analysis, we were able to identify individual phenotypic leukemic cell aberrations in up to 98% of investigated cases. CD10 and/or CD45RA were aberrant in 86% of cases overall, emphasizing the high discriminative potential of these two markers. Using comparative phenotype mapping based on quantitatively aberrant, leukemia-associated antigenic patterns, we were able to detect leukemic blasts among normal bone marrow cells at frequencies as low as 10(-5). We speculate that our approach may have a profound impact on the development of new strategies for minimal residual disease investigations in patients with BCP-ALL.

A novel bioassay for P-glycoprotein functionality using cytochalasin D

The functional contribution of both P-glycoprotein (P-gp) and the multidrug resistance-associated protein (MRP) to multidrug resistance (MDR) in tumor cells is commonly determined by drug cytotoxicity and/or accumulation/efflux tests. We report on a bioassay developed for the specific detection of functional P-gp levels and the efficacy of related chemosensitizers (CD-P-gp-assay). The assay is based on the flow cytometric measurement of changes in the > or = G2M cell cycle compartment which are due to the induction of polykaryons after exposure of proliferating cells to three defined cytochalasin D (CD) concentrations with and without verapamil. As demonstrated in 13 well-characterized MDR cell models (20 resistant sublines), there is a significant correlation between cytokinesis-blocking CD doses, as well as responsiveness to chemosensitizers and MDR1 gene expression (mRNA and P-gp) allowing discrimination between different levels of P-gp-MDR. CD-P-gp-assay specificity was assessed by testing 23 compounds: 19 known as potent inhibitors of P-gp-MDR, some of them, though to a lesser extent, also of MRP-MDR; 1 inhibiting MRP-but not P-gp-MDR; 3 inactive in both types of MDR. A modulation of CD activity was confined exclusively to both P-gp-expressing cell lines and P-gp chemosensitizers. CD cytoskeletal activity measured by FACS is a specific and sensitive tool with which to detect functional P-gp and related chemosensitizers.

Quantification of CD34+ cells: comparison of methods

BACKGROUND

Quantification of CD34+ stem and progenitor cells is predominantly performed by flow cytometric analysis of cells prepared by whole blood staining and red cell lysis. This method also includes cell washing, which is thought to cause the destruction and loss of some of the nucleated cells (NCs). To address this cell loss and its influence on the outcome of enumeration, three techniques for preparing cells for quantification of CD34+ cells were compared.

STUDY DESIGN AND METHODS

Blood (n = 179), bone marrow (n = 60), and leukapheresis components (n = 64) were examined by the use of density separation of mononuclear cells (MNCs) and two red cell-lysis procedures (wash and no-wash). Cell counts were determined in the original materials and after cell preparation. Absolute CD34+ cell counts were calculated using the flow cytometry-analyzed proportions of CD34+ cells and the various white cell counts.

RESULTS

Depending on the cell source and the cell preparation chosen, the loss of NCs ranged between 12 percent and 89 percent of the original white cell number. This loss of NCs was exclusively due to cell washing and predominantly affected granulocytic cells. Analysis of the flow cytometry data revealed that the relative CD34+ values in blood and bone marrow were roughly threefold higher in density separated MNCs than in those that underwent the lyse-and-wash procedure. Calculation of absolute CD34+ cell counts confirmed that the MNC procedure underestimated the CD34+ cell content by a median of 26 percent (blood), 21 percent (bone marrow), and 5 percent (leukapheresis component) when compared with the median yield from analysis and cell counting performed after the lyse-and-wash procedure. On the other hand, the conventional lysis procedure, which applies the original white cell counts for CD34+ quantification, was shown to overestimate the CD34+ cell content by a median of 1.2-fold, 1.33-fold, and 1.13-fold, respectively.

CONCLUSION

Neither density separation nor the whole-blood lysis procedure seems appropriate for optimal CD34+ quantification.

Multiparameter phenotype mapping of normal and post-chemotherapy B lymphopoiesis in pediatric bone marrow

We studied the differentiation profiles of B cell precursors (BCP) in normal and post-chemotherapy pediatric bone marrow (BM) using multiparameter flow cytometry. The goal of our study was to draw a comprehensive phenotypic map of the three major maturational BCP stages in BM. By correlating lineage-associated markers, CD45RA, and several adhesion molecules, the stage-specific patterns were found to differ in certain details from previously published concepts. Among the earliest BCP, a subset of CD34+ CD10(lo) precursors was repeatedly observed in addition to the well characterized CD34+ CD10(hi) CD19+ majority of cells. Only two-thirds of these CD34+ CD10(lo) cells expressed CD19. However, uniformity of phenotypic features, absence of T lineage markers, and the regeneration kinetics after chemotherapy suggest the B lineage affiliation of the CD34+ CD10(lo) precursors in general. In the more mature BCP, expression of CD10, CD20, cytoplasmic and surface mu chains (c mu and s mu) was observed to overlap more than previously recognized. We found that CD20 and c mu appear early during B cell ontogeny (already on CD34+ BCP), and that CD10 is lost late, following the onset of s mu expression. Differences between normal and post-chemotherapy BM specimens regarding the phenotypic appearance of BCP were exclusively due to differences in the subset composition, as post-chemotherapy samples showed a preponderance of immature stages. Our observations may build a framework for comparing leukemic cells with their normal counterparts to define possible leukemia-associated aberrations useful for residual disease studies.

Acute leukemias express a functional receptor for the human growth hormone

The potential influence of the human growth hormone (hGH) on the behavior of acute leukemias is a matter of controversy. We investigated primary childhood and adult leukemias (n = 44) and leukemic cell lines (n = 13) for the expression of the hGH receptor (hGHR) by immunohistochemistry and flow cytometry. All leukemias expressed the hGHR in the cytoplasm; expression on the surface was undetectable in some of the leukemias. In leukemic cell lines, hGHR expression on the surface was demonstrated in a dose-dependent manner after incubation with rhGH. Physiologic concentrations of hGH were more efficient than higher doses in increasing hGHR surface expression. A proliferative response to hGH was accomplished in cell lines REH, Molt4, and K562. However, only one of 19 primary leukemias (ALL, n = 12; AML, n = 7) showed increased cell counts after the addition of 50-800 ng/ml recombinant hGH (rhGH). These cells were of an immature T-cell phenotype. We thus conclude that acute leukemias can be stimulated by hGH to up-regulate its receptor, but that most primary leukemias may require additional signals for the induction of proliferation.

Spiking fevers with clozapine treatment

Clozapine often causes low-grade fever and less frequently spiking fever. We describe three cases of spiking fever that occurred in the first 3 weeks of clozapine therapy. A new set of side effects of clozapine is identified, which includes spiking fever, respiratory and gastrointestinal symptoms, and neutrophilia. Possible mechanisms are discussed.