[Bone marrow fibrosis in primary myelofibrosis in relation to myelodysplasia- and age-related mutations of hematopoietic cells]. / Knochenmarkfibrose bei primärer Myelofibrose in Abhängigkeit von myelodysplasie- und altersassoziierten Mutationen der Hämatopoese.

Besides histopathological findings, there are no indicators of increased risk for fibrotic progression in myeloproliferative neoplasms (MPNs). Age-related clonal hematopoiesis (ARCH) or clonal hematopoiesis of indetermined potential (CHIP) are frequent findings in the elderly and combinations with MPN driver mutations (JAK2, MPL, and CALR) have been described. To determine the impact of ARCH/CHIP-related mutations for the development of fibrosis in primary myelofibrosis (PMF), the mutational status of cases with fibrotic progression from grade 0 to grade 2/3 (n = 77) as evidenced by follow-up bone marrow biopsies (median 6.2 years) was compared to prefibrotic PMF samples without the development of fibrosis (n = 27; median follow-up 7.3 years). Frequent ARCH/CHIP-associated mutations (TET2, ASXL1, DNMT3A) demonstrable at presentation were not connected with fibrotic progression. However, mutations that are rarely found in ARCH/CHIP (SRSF2, U2AF1, SF3B1, IDH1/2, and EZH2) were present in 24.7% of cases with later development of fibrosis and not detectable in cases staying free from fibrosis (P = 0.0028). Determination of tumor mutational burden (TMB) in a subgroup of cases (n = 32) did not show significant differences (7.68 mutations/MB vs. 6.85 mutations/MB). We conclude that mutations rarely found in ARCH/CHIP provide an independent risk factor for rapid fibrotic progression (median 2.0 years) when already manifest at first presentation.

[Myeloproliferative neoplasms: histopathological and molecular pathological diagnosis]. / Myeloproliferative Neoplasien: Histopathologische und molekularpathologische Diagnostik.

Myeloproliferative neoplasms (chronic myeloproliferative disorders according to former nomenclature) comprise chronic myeloid leukemia, polycythemia vera, essential thrombocythemia, primary myelofibrosis, chronic eosinophilic leukemia, chronic neutrophilic leukemia and systemic mastocytosis. All disorders have excessive proliferation of one or more hematopoietic lineages in common and progress with different probability to blast crisis or fibrosis. A further common feature is provided by the activating mutation of tyrosin kinases and associated pathways of signal transduction (BCR-ABL, JAK2(V617F), MPL(W515L/K), KIT(D816V) and FIP1L1-PDGFRA) causative for the abnormal proliferation. With regard to diagnosis and therapy these mutations are of utmost importance because they enable the exclusion of reactive processes, contribute with varying specificity to subtyping of MPN and are at least partly sensitive to targeted therapy. The molecular mechanisms of blastic and fibrotic progression are not yet understood.

Lentiviral vectors for induction of self-differentiation and conditional ablation of dendritic cells.

Development of lentiviral vectors (LVs) in the field of immunotherapy and immune regeneration will strongly rely on biosafety of the gene transfer. We demonstrated previously the feasibility of ex vivo genetic programming of mouse bone marrow precursors with LVs encoding granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), which induced autonomous differentiation of long-lived dendritic cells (DCs), referred to as self-differentiated myeloid-derived antigen-presenting-cells reactive against tumors (SMART-DCs). Here, LV biosafety was enhanced by using a DC-restricted and physiological promoter, the major histocompatibility complex (MHC) II promoter, and including co-expression of the herpes simplex virus-thymidine kinase (sr39HSV-TK) conditional suicide gene. Tricistronic vectors co-expressing sr39HSV-TK, GM-CSF and IL-4 transcriptionally regulated by the MHCII promoter or the ubiquitous cytomegalovirus (CMV) promoter were compared. Despite the different gene transfer effects, such as the kinetics, levels of transgene expression and persistency of integrated vector copies, both vectors induced highly viable SMART-DCs, which persisted for at least 70 days in vivo and could be ablated with the pro-drug Ganciclovir (GCV). SMART-DCs co-expressing the tyrosine-related protein 2 melanoma antigen administered subcutaneously generated antigen-specific, anti-melanoma protective and therapeutic responses in the mouse B16 melanoma model. GCV administration after immunotherapy did not abrogate DC vaccination efficacy. This demonstrates proof-of-principle of genetically programmed DCs that can be ablated pharmacologically.

Long-term outcome of patients with newly diagnosed chronic myeloid leukemia: a randomized comparison of stem cell transplantation with drug treatment.

Tyrosine kinase inhibitors represent today's treatment of choice in chronic myeloid leukemia (CML). Allogeneic hematopoietic stem cell transplantation (HSCT) is regarded as salvage therapy. This prospective randomized CML-study IIIA recruited 669 patients with newly diagnosed CML between July 1997 and January 2004 from 143 centers. Of these, 427 patients were considered eligible for HSCT and were randomized by availability of a matched family donor between primary HSCT (group A; N=166 patients) and best available drug treatment (group B; N=261). Primary end point was long-term survival. Survival probabilities were not different between groups A and B (10-year survival: 0.76 (95% confidence interval (CI): 0.69-0.82) vs 0.69 (95% CI: 0.61-0.76)), but influenced by disease and transplant risk. Patients with a low transplant risk showed superior survival compared with patients with high- (P<0.001) and non-high-risk disease (P=0.047) in group B; after entering blast crisis, survival was not different with or without HSCT. Significantly more patients in group A were in molecular remission (56% vs 39%; P=0.005) and free of drug treatment (56% vs 6%; P<0.001). Differences in symptoms and Karnofsky score were not significant. In the era of tyrosine kinase inhibitors, HSCT remains a valid option when both disease and transplant risk are considered.

Frequency of pseudo-Gaucher cells in diagnostic bone marrow biopsies from patients with Ph-positive chronic myeloid leukaemia.

Pseudo-Gaucher cells (PGC) are a characteristic finding in Ph-positive CML, and prolongation of survival was observed when PGC were detected within the bone marrow. However, the conspicuous variation in the reported frequencies indicates the necessity for analysis of their natural occurrence in the bone marrow from untreated CML patients. A total of 833 diagnostic bone marrow biopsies from patients with Ph-positive CML were examined for PGC by 7 observers. Proof of PGC was based on systematic examination of Giemsa-stained slides with and without polarization at high magnification. Birefringence within the cytoplasm turned out to be highly specific for PGC. The risk of overlooking PGC was at least 80% when the number of these storing histiocytes was 70 per slide or less, and at least 50% when the total amount per slide was < or = 250. This high risk of failure explained the disagreement among the authors. An intensive investigation by at least two observers is mandatory if results are to be evaluated in research. Under the conditions used in this study, the natural frequency of PGC within the bone marrow from untreated patients with a Ph-positive CML is much higher than assumed to date, amounting to about 70%. On the basis of these findings, the prognostic importance of PGC in CML must be evaluated critically.

Cytogenetic aberrations in myelodysplastic syndrome detected by comparative genomic hybridization and fluorescence in situ hybridization.

Conventional cytogenetics (CC) is proven as a diagnostic and prognostic factor in myelodysplastic syndrome (MDS). However, CC may be hampered by insufficient metaphase preparation and cannot analyze interphase nuclei. These problems are solved by using comparative genomic hybridization (CGH). The CGH was applied to samples from 45 patients with MDS, and the results were compared with CC and fluorescence in situ hybridization (FISH). The CC detected aberrations in 12 of 45 samples, including chromosomes 3 (n = 1), 5 (n = 9), 7 (n = 2),8(n = 1), 18(n = 1),21 (n = 1), X (n = 1), and Y(n = 2). In one patient, loss of B and C group chromosomes and a marker chromosome were seen. The CGH revealed chromosomal imbalances in 18 of 45 samples, including chromosomes 5 (n = 11), 7 (n = 2), 8 (n = 1), 18(n = 1), 20(n = 1), 21 (n = 1), X (n = 1), and Y (n = 2). All unbalanced aberrations found by CC were detected by CGH, too. In two patients, the CGH found additional aberrations and redefined the aberrations of the chromosomes of the B and C group in one sample. The FISH confirmed these aberrations. Additionally performed FISH for chromosomes 5, 7, and 8 gave normal findings in all patients found to be normal in CC and CGH. The CGH and FISH confirmed the results obtained by CC. All three techniques showed changes of chromosomes 5 and 7 as the most frequent aberrations, emphasizing the importance of these chromosomes in the development of MDS. Furthermore, the CC is proven as the basic technique for cytogenetic evaluation of MDS.

Selection for Evi1 activation in myelomonocytic leukemia induced by hyperactive signaling through wild-type NRas.

Activation of NRas signaling is frequently found in human myeloid leukemia and can be induced by activating mutations as well as by mutations in receptors or signaling molecules upstream of NRas. To study NRas-induced leukemogenesis, we retrovirally overexpressed wild-type NRas in a murine bone marrow transplantation (BMT) model in C57BL/6J mice. Overexpression of wild-type NRas caused myelomonocytic leukemias ∼3 months after BMT in the majority of mice. A subset of mice (30%) developed malignant histiocytosis similar to mice that received mutationally activated NRas(G12D)-expressing bone marrow. Aberrant Ras signaling was demonstrated in cells expressing mutationally active or wild-type NRas, as increased activation of Erk and Akt was observed in both models. However, more NRas(G12D) were found to be in the activated, GTP-bound state in comparison with wild-type NRas. Consistent with observations reported for primary human myelomonocytic leukemia cells, Stat5 activation was also detected in murine leukemic cells. Furthermore, clonal evolution was detected in NRas wild-type-induced leukemias, including expansion of clones containing activating vector insertions in known oncogenes, such as Evi1 and Prdm16. In vitro cooperation of NRas and Evi1 improved long-term expansion of primary murine bone marrow cells. Evi1-positive cells upregulated Bcl-2 and may, therefore, provide anti-apoptotic signals that collaborate with the NRas-induced proliferative effects. As activation of Evi1 has been shown to coincide with NRAS mutations in human acute myeloid leukemia, our murine model recapitulates crucial events in human leukemogenesis.

[Histopathology of chronic myeloid leukemia in diagnostic biopsies of bone marrow]. / Histopathologie der chronischen myeloischen Leukämie in diagnostischen Biopsien vom Knochenmark.

Histopathology of the bone marrow of diagnostic biopsies prior to any therapy is described in a total of 412 Ph1-positive patients. Special attention is paid to the distribution of megakaryocytes, increase of fibres and blasts, and occurrence of storing histiocytes of pseudo-Gaucher type. Megakaryocytes were significantly increased in 31.6% of diagnostic biopsies, myelofibrosis was found in 15.8%, significant increase of blasts in 2.4%. Pseudo-Gaucher cells were detected in 57.8% of a total of 412 biopsies. These histiological features are considered as an indication of the progress of the disease. A semiquantitative specification of CML by this criteria is described which can be performed rather reliably and defines the stage of CML at diagnosis prior to substantial treatment.

Square sampling. An easy method of estimating numerical densities of cells or particles within a tissue.

OBJECTIVE: A new parametric method is presented, called "square sampling," which speeds up the estimate of the number of cells or particles that are randomly distributed within a tissue. STUDY DESIGN: The principle of square sampling is subdivision of a biopsy into at least 100 squares of the same size using a measuring ocular or computer-based morphometric system and estimating the cell number by counting "positive" squares, squares with at least one cell of interest, assuming a binomial distribution of positive squares, depending on numerical density. RESULTS: The derived estimate yielded almost identical results when compared with the exact count of pseudo-Gaucher cells within bone marrow biopsies from untreated patients with chronic myeloid leukemia (r = .97, examined area = 94 x 2 mm2, with 400 squares/2 mm2), but (1) the total time of investigation could be halved by square sampling (25.1 versus 55.3 hours, P < .00005), and (2) the estimated number of cells did not very more widely around the mean exact count than the cell numbers exactly counted (P > .05). CONCLUSION: Square sampling is an easy, fast and effective alternative to nonparametric approaches in order to quantify the numerical density of cells randomly distributed within a tissue. The method can also be applied to test hypotheses of random distribution as well as to quantify a clustering of cells in cases of nonrandom cell distribution.

Immunophenotype of hairy-cell leukaemia after cold polymerization of methyl-methacrylate embeddings from 50 diagnostic bone marrow biopsies.

Hairy-cell leukaemia may be difficult to diagnose in bone marrow biopsies, especially in the early stages or in its residum after complete clinical remission. To consider the impact of published data on immunophenotyping hairy-cell leukaemias, a total of 50 diagnostic biopsies were systematically analysed with a panel of eight antibodies and compared with cases of chronic lymphatic leukaemia (CLL), 20 follicular centre lymphomas, 20 lympho-plasmacytoid immunocytomas, 10 small-cell T-cell non-Hodgkin lymphomas and 20 cases of benign nodular lymphatic hyperplasia. The panel of eight antibodies comprised DBA44, CD45, CD20, CD45R, CD45RO, CD43 and the CD68 antibodies KP1 and Ki-M1P. The hairy-cell leukaemias were staged histologically into four categories of bone marrow infiltration. DBA44 reacted positively in 47/50 cases. CD45 and the B-cell markers CD20 and CD45R reacted in 49/50 and 43/50 cases, respectively. One CD68 marker, KP1, was positive in 38/50 cases but the other-Ki-M1P-only in 1/50 cases. Chronic lymphatic leukaemia cases, the other B-cell NHLs and lymphatic hyperplasias showed strong positivity for CD20 and CD45R, but only the immunocytomas reacted with DBA44 in 7/20 cases. The T-cell NHLs and hyperplasias showed a strong positivity for the T-cell markers CD45RO and CD43. The CD68-marker Ki-M1P revealed a high specificity since it was negative in all NHLs and positive only in one hairy-cell leukaemia. Methyl-methacrylate embedding of bone marrow biopsies under cold polymerization produces a high quality of histo- and cytomorphology, resulting in greater diagnostic reliability and the detection of low-stage infiltration of hairy-cell leukaemia. DBA44 appears as a highly specific antibody to mark hairy-cells since only immunocytomas reacted positively in a few cases. A small panel of antibodies including DBA44. CD20, CD45R and Ki-M1P may serve to distinguish small-cell. NHL from hairy-cell leukaemia even at an early stage or when there are minimal residual tumour cells.