[Myelodysplastic syndromes. Epidemiology, molecular and morphological characteristics and risk stratification]

Myelodysplastic syndromes (MDS) comprise a spectrum of clonal stem cell disorders which are currently defined according to the classification scheme of the revised 2008 WHO classification but which may be further refined in the future. The clinical presentation is often characterized by unexplained isolated or multiple peripheral blood cytopenias resulting in anemia, bleeding events or increased susceptibility to infections. The generally hypercellular, but rarely hypocellular and occasionally fibrotic bone marrow shows dysplastic features in ≥ 10 % of cells of at least one of the hematopoietic lineages. These features and enhanced apoptosis, stem cell senescence and immunologic dysregulation result in ineffective hematopoiesis. Diagnostics in MDS relies on complementary consideration of hematological, morphological and cytogenetic/molecular parameters. Methods include marrow and peripheral blood cytology, cytogenetics, fluorescence in situ hybridization (FISH), trephine bone marrow biopsy examination, immunophenotyping and the evaluation of molecular markers by established and new techniques. Mutations affecting growth factor receptors, cell cycle and apoptosis regulators, intracellular signaling, transcription factors, epigenetic regulation and the splicosome are involved in MDS pathogenesis and progression.

Evidence of clonality in chronic neutrophilic leukaemia

BACKGROUND

Chronic neutrophilic leukaemia (CNL) is a rare myeloproliferative disorder of elderly patients characterised by sustained neutrophilia and splenomegaly. The diagnosis of CNL requires the exclusion of BCR/ABL positive chronic myelogenous leukaemia (CML) and of leukaemoid reactions (LRs). The differentiation between CNL and LR is problematic because both conditions share similar morphological features; it is also important because patients with CNL generally have a poor prognosis.

AIMS

To determine whether CNL and LR could be distinguished on the basis of different clonality patterns.

METHODS

Blood samples from 52 women were studied using the human androgen receptor gene assay (HUMARA).

RESULTS

Monoclonality was found in the neutrophils in all 17 patients with different myeloproliferative syndromes (MPSs), including those with CNL. In four of the patients with CNL, autologous T cells were also monoclonal, suggesting that they belonged to the neoplastic clone. This finding was in contrast to other MPSs in which T cells were almost always polyclonal. Of nine patients with clinically suspected LR, the neutrophils of five were polyclonal, whereas three patients had monoclonal neutrophils, suggesting that they might be in the process of developing an MPS. Among 26 healthy blood donors, 20 had polyclonal neutrophils and five showed skewed clonality patterns. One case of LR and one normal blood donor were scored "not informative" at the HUMARA locus.

CONCLUSIONS

Clonality studies of blood neutrophils using HUMARA aid in distinguishing female patients with monoclonal CNL from those with LR. For the diagnosis of CNL, monoclonality of the neutrophils should be demonstrated whenever possible.

Innate T-cell immunity in HIV infection: the role of Vgamma9Vdelta2 T lymphocytes

There is growing interest in the use of innate immune reactions in the therapy and prophylaxis of various diseases. Natural T (NT) lymphocytes that recognize infected cells or microbial compounds without the classical genetic restriction by polymorphic MHC molecules are crucial components of innate immunity. NT cells bearing the Vgamma9Vdelta2 T-cell receptor (TCR) are broadly reactive against intracellular pathogens, can lyse human immunodeficiency virus (HIV) infected cells, and release cytokines capable of regulating HIV replication. The potent antiviral activities of Vgamma9Vdelta2 T cells may help to contain viral spread during acute HIV infection and/or to prevent the establishment of viral persistence. Substantial changes in the composition and function of circulating gammadelta T-cell pools occur in HIV-infected patients. These changes a) may contribute to the etiopathogenesis of opportunistic infections and neoplasms, and b) are partly reversed by highly active anti-retroviral therapy (HAART). In addition to direct antiviral activities, activated gammadelta T cells influence dendritic cell maturation and the adaptive alphabeta T-cell response. Vgamma9Vdelta2 T cells can be stimulated in vivo and in vitro by various nonpeptidic antigens (NpAgs) and recent animal experimental data suggest that activated Vgamma9Vdelta2 T cells may help to control SIV replication. Currently, NpAgs are being assessed as potential therapeutic agents in AIDS, tuberculosis and certain cancers susceptible to Vgamma9Vdelta2 T-cell effector mechanisms.

[Coincidence of chronic idiopathic myelofibrosis and chronic lymphocytic leukaemia. A rare phenomenon?]

In 1986 we diagnosed chronic idiopathic myelofibrosis (CIMF) in a 45-year-old asymptomatic patient with hepatosplenomegaly. In 1996 splenectomy was performed because of hypersplenism, and chemotherapy with hydroxyurea was initiated. In 1999 generalised lymphadenopathy of chronic lymphocytic leukaemia (B-CLL) developed. A trephine biopsy showed leukaemic bone marrow infiltration. On heteroduplex analysis we found a clonal rearrangement of IgH in the leukaemic lymphocytes. The coincidence of chronic myeloproliferative and lymphoproliferative diseases in the same patient is a rare phenomenon. According to the relevant literature, seven cases with a combination of CIMF/CLL have been reported. Possible pathomechanisms for the development of such coincidences are: 1) a bilineage manifestation of a pluripotent stem cell proliferation, 2) independent proliferations of two distinct cell lines under a common leukaemogenic stimulus or 3) an accidental association. These coincidence cases often showed a mild clinical course and also in our case, the patient is still alive and in a stable disease condition 16 years after the initial diagnosis.

[Clonality as a criterion in the differential diagnosis of chronic neutrophilic leukaemia]

Chronic neutrophilic leukaemia (CNL) is a rare BCR/ABL negative myeloproliferative disorder of elderly patients, showing sustained neutrophilia and splenomegaly. Differentiation between CNL and leukaemoid reactions (LR) is problematic since both conditions share similar morphological features but is essential because CNL patients generally have a poor prognosis. We studied blood samples from 10 female patients with CNL or LR using the HUMARA assay to determine clonality patterns in neutrophils. T-lymphocytes of the patients were investigated as an internal control cell population. In all five CNL patients the neutrophils, and in four of them also T-lymphocytes were monoclonal, indicating that the latter may also originate from the neoplastic clone. In LR patients the neutrophils and T-lymphocytes were generally polyclonal except in one patient showing monoclonal neutrophils suggesting that this patient might be in the process of developing a myeloproliferative disorder. In females clonality studies of blood neutrophils using HUMARA aid in distinguishing patients with monoclonal CNL from polyclonal LR.

An acidic microenvironment inhibits antitumoral non-major histocompatibility complex-restricted cytotoxicity: implications for cancer immunotherapy

Local immunosuppression may explain the failure of an effective immune response against solid tumors. Although it is well known that the interstitial pH is significantly lower in solid tumors than in normal tissue, only a few studies in the mouse system have investigated the influence of this acidic milieu on the anti-tumoral cytotoxic response. Here the authors report the suppression of human non-major histocompatibility complex (MHC)-restricted cytotoxicity against tumor cells by an acidic extracellular pH (pHe). Unstimulated peripheral blood mononuclear cells, lymphokine-activated killer (LAK) cells, and natural killer cell clones were used as effector cells. According to pH measurements in solid tumors, representative pH values of 7.2 to 5.3 were chosen during the cytotoxic assays. Target cell lysis was measured using two nonradioactive fluorometric methods, namely two-color flow cytometry and a modified calcein-release assay, which allowed cell-mediated cytotoxicity to be measured and compared with that in adherent targets. Using K562, Daudi, or Raji as suspended target cell lines, the cytotoxic activity of unstimulated peripheral blood mononuclear cells and of LAK cells was markedly reduced by a decreasing pHe. An extracellular pH of 5.8 to 5.3 resulted in a nearly complete loss of the cytotoxic response. This pHe-dependent impairment of the killing activity could also be shown for killer cells stimulated with interleukins-7 and -12, phytohemagglutinin, or lipopolysaccharide. The lytic potential of homogeneous natural killer cell clones as effectors was also strictly influenced by the surrounding pH. The pHe dependence of the non-MHC-restricted killer cell functions against tumor cells seems to be a general phenomenon, because the cytolytic activity of LAK cells against six human adherent tumor cell lines (HeLa, HepG2, LS174T, LS174Te, MCF-7, and RT112) was also clearly reduced under acidic conditions. To initiate the killing process, adhesion molecules play an important role in recognition and binding of the target cell. However, flow cytometric analysis revealed that the expression pattern of relevant adhesion molecules was unaffected by acidic pHe. In conclusion, these data clearly indicate an inhibition of non-MHC-restricted cytotoxicity against tumor cells by an acidic pHe, which may contribute to the failure of immunosurveillance against solid tumors. Consequently, efforts to enhance the anti-tumoral cytotoxicity by immunotherapies may have limited success.

Stimulation of cytotoxic T cells against idiotype immunoglobulin of malignant lymphoma with protein-pulsed or idiotype-transduced dendritic cells

Because of their hypervariable regions and somatic mutations, the antigen receptor molecules of lymphomas (idiotypes) are tumor-specific antigens and attractive targets for antilymphoma immunotherapy. For the optimal induction of human idiotype-specific cytotoxic T cells (CTL), idiotype was presented to CD8(+) peripheral blood mononuclear cells by monocyte-derived autologous dendritic cells (DC) after the endocytosis of idiotype protein or by idiotype-expressing DC. Recombinant idiotype was obtained as a functionally folded Fab fragment by periplasmic expression in Escherichia coli. Idiotype-expressing DC were generated by transduction with recombinant Semliki forest virus vectors encompassing heavy- or light-chain idiotype genes. Autologous lymphoblastoid cell lines stably transfected with Epstein-Barr virus-based idiotype expression vectors were used as target cells to detect idiotype-specific lysis. CTL stimulated with idiotype-loaded DC showed strong specific, CD8-mediated, and major histocompatibility complex (MHC) class I-restricted cytotoxicity against autologous heavy- and light-chain idiotype. In contrast, stimulation with idiotype-transduced DC resulted in only moderate natural killer cell activity. These data confirm the existence of idiotype-specific CTL in patients with lymphoma, define a "good manufacturing practice"-compatible protocol for the generation of these cells without the requirement of viable lymphoma cells, and favor the processing of exogenous antigen over DC transduction for the induction of MHC I-restricted CTL against idiotypes with unknown antigenicity. (Blood. 2000;95:1342-1349)

Rapid expression cloning of human immunoglobulin Fab fragments for the analysis of antigen specificity of B cell lymphomas and anti-idiotype lymphoma vaccination

An expression system for rapid and standardized production of human recombinant immunoglobulin Fab fragments in E. coli was developed. Functional folding of the Fab fragments was accomplished by the dicistronic expression vector pFab.gammakappa containing specialized leader sequences to direct the immunoglobulin heavy and light chains to the periplasmic bacterial space. A C-terminal hexahistidine tag of the Fd chain facilitated metal affinity chromatography and purification to homogeneity as assessed by SDS PAGE and silver staining. Specific antigen recognition by a hybridoma-derived Fab fragment was indistinguishable from that of the corresponding monoclonal antibody. This protocol may be useful for analysis of the antigen specificity of human B cells and for convenient production of lymphoma-derived idiotype protein for vaccination strategies. To obtain unmodified immunoglobulin cDNA sequences from small human biopsies for insertion into pFab.gammakappa, oligo(dG)-tailed cDNA was amplified with an oligo(dC)- and nested mu or kappa constant region-specific primers. Using single sets of primers for each class of immunoglobulin transcripts, the products of this anchored PCR reflected the relative abundance of the starting cell population and permitted reliable identification of clonal, lymphoma-derived sequences for subsequent expression cloning.

In vitro fertilization and intracytoplasmic sperm injection pregnancies after successful transport of oocytes by airplane

OBJECTIVE

To determine the feasibility of a transport IVF program involving air transportation of oocytes.

DESIGN

Prospective cohort study.

SETTING

Regional hospital (Hôpital de Chicoutimi) and University Infertility Center (McGill Reproductive Center, Montreal).

PATIENT(S)

The first series of patients referred for IVF or IVF and ICSI, for a variety of indications, who opted for inclusion in the transport IVF program.

INTERVENTION(S)

The IVF-ET with ovarian stimulation and oocyte collection at the peripheral unit and transport of the oocytes by airplane to the McGill Reproductive Center where IVF or ICSI was performed.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy.

RESULT(S)

Seven couples, in the first series, underwent nine cycles of transport IVF treatment. Two also underwent ICSI. There were two clinical pregnancies.

CONCLUSION(S)

Transport IVF using air travel is possible and opens the possibility for this type of program to be implemented in large countries with scattered populations, such as the United States, Canada, and Australia.

Pro-inflammatory and T cell inhibitory cytokines are secreted at high levels in tumor cell cultures of human renal cell carcinoma

OBJECTIVES

The objectives of this study were to assess cytokine secretion in human renal cell carcinoma (RCC) and to identify cytokines contributing to the immunomodulatory effect of tumor cells.

METHODS

Cytokine secretion in the supernatant of primary tumor cell cultures (PTCC) and corresponding cell lines (CL) was assayed using ELISA. Tumor cells were characterized by morphology, immunocytochemistry, and flow-cytometric analysis. Tumor-cell-induced T cell activation was determined by coculture of gamma delta and alpha beta T cell clones with tumor CL.

RESULTS

We assessed the cytokine secretion of tumor cells from 27 PTCC and their corresponding CL (3/27) of RCC. We found that RCC predominantly produced both pro-inflammatory and T-cell-inhibitory cytokines, such as IL-8, IL-6, GM-CSF, TNF-alpha, IL-10 and TGF-beta 1. CL were adapted to serum-free medium which may prove as a useful tool in future studies of cytokine secretion in RCC. In addition, we used gamma delta and alpha beta T cell clones to assess the immunomodulatory effect of tumor cells from RCC and found that predominantly gamma delta T cells were activated by RCC.

CONCLUSIONS

Our data suggest that RCC produce large amounts of both pro-inflammatory and T-cell-inhibitory cytokines that potentially could influence the immune response of the host, especially tumor-specific cytotoxic T cells.

Cell lines transfected with the TAP inhibitor ICP47 allow testing peptide binding to a variety of HLA class I molecules

The immediate early protein ICP47 of the Herpes simplex virus is known to block the human transporter associated with antigen processing (TAP), thereby creating a TAP-deficient phenotype in any human cell transfected with the corresponding cDNA. Exploiting this inhibitory activity, we constructed a selection of human cell lines each co-expressing one of the cDNAs of human leukocyte antigen (HLA) class I alleles HLA-A*1101, A24, A*3101, A*6601, B8 and B*1516, and the cDNA encoding the ICP47 molecule. The cell lines generated showed diminished HLA class I surface expression and the inhibition of the TAP function was confirmed in peptide translocation assays. The addition of specific exogenous peptide ligands restored the expression of the corresponding HLA class I molecules. Thus, the ICP47 transfectants provide us with a tool to closely examine peptide-HLA class I interactions, to confirm HLA class I ligand motifs and to test peptides predicted to bind.

Novel molecular and cellular strategies in cancer therapy

Tumor initiation and progression results from several subsequent mutations in genes that control cellular proliferation and differentiation. Neoplasia may lead to the expression of antigens that may be derived from such oncogenes or the activation of other cellular or viral genes that may represent tumor associated antigens. This review summarizes the present understanding of these mechanisms in an effort to design new therapeutic strategies.