Prognostic factors in the acute lymphoid and myeloid leukemias of infants

The age boundaries and prognostic factors that define the infant leukemias are still controversial. We therefore analyzed event-free survival according to age group in 96 children treated for acute lymphoblastic leukemia (ALL) and 51 treated for acute myeloid leukemia (AML) before the age of 2 years. The study population was registered in consecutive institutional trials of multiagent chemotherapy conducted between 1980 and 1994. Among infants with ALL, event-free survival was significantly poorer in the 0- to 6-month-old group than in patients treated between 6 and 12 months of age (P = 0.03), whose outcome was in turn inferior to that in the 12- to 18-month and 18- to 24-month age groups (P = 0.013). Leukemic cells from ALL patients younger than 12 months had a significantly higher frequency of 11q23/MLL abnormalities, as well as better growth in stromal cell culture, compared to lymphoblasts from the older groups (P < 0.01). The only independent predictor of adverse prognosis among infants diagnosed with ALL before age 12 months was the presence of an 11q23/MLL rearrangement (P = 0.03). These findings contrast sharply with results for the AML cohort, whose event-free survival did not vary significantly by age group (P = 0.58). Male sex (P = 0.01) and leukocyte count > or = 50 x 10(9/l) (P = 0.04), but not 11q23 abnormalities, were independently associated with a poorer outcome for children with AML younger than 12 months at diagnosis. Thus, in very young children with ALL (but not AML), the rearrangement status of the 11q23/MLL region supersedes age group as a determinant of treatment outcome.     

Leukocyte differentiation antigens. How to keep up with the litany of CD antigens

Distigmine bromide is a long-acting anticholinesterase, available for the treatment of postoperative urinary retention. Its effectiveness is unproven and administration may be hazardous. We describe a case in which oral distigmine bromide was used for postoperative retention, resulting in a potentially life-threatening 'cholinergic crisis'. We review the literature and conclude that the use of oral distigmine bromide in postoperative urinary retention is not justified.     

Prognostic value of P-glycoprotein and leukocyte differentiation antigens in chronic myeloid leukemia

P-glycoprotein (Pgp) mediated multidrug resistance is often the cause of therapy failure in some tumors. Pgp expression was shown to have prognostic value in several hematological malignancies, especially in acute myeloblastic leukemia (AML) and acute lymphoblastic leukemia (ALL). In chronic myeloid leukemia (CML) Pgp is expressed by peripheral blood (PB) cells more often in the terminal disease stages (20-50% of patients have Pgp+ phenotype). Sequential studies show that Pgp+ cells often disappear from the PB during the course of therapy. Nevertheless Pgp expression has some prognostic value in blast crisis (BC) predicting shorter BC, while CD13 has the same predictive value in BC. 10% of patients formed a distinct group with large numbers of Pgp+CD34+ blasts in the PB and also had shorter BC. Cases with inactive Pgp were found in chronic and accelerated phases of CML but not in BC.     

The reliability and specificity of c-kit for the diagnosis of acute myeloid leukemias and undifferentiated leukemias. The European Group for the Immunological Classification of Leukemias (EGIL)

We document findings on c-kit (CD117) expression in 1,937 pediatric and adult de novo acute leukemia cases, diagnosed in five single European centers. All cases were well characterized as to the morphologic, cytochemical, and immunologic features, according to the European Group for the Immunological Classification of Leukemias (EGIL). The cases included 1,103 acute myeloid leukemia (AML), 819 acute lymphoblastic leukemia (ALL), 11 biphenotypic acute leukemia (BAL), and 4 undifferentiated (AUL). c-kit was expressed in 741 (67%) AML cases, regardless of the French-American-British (FAB) subtype, one third of BAL, all four AUL, but only in 34 (4%) of ALL cases. The minority of c-kit+ ALL cases were classified as: T-cell lineage (two thirds), mainly pro-T-ALL or T-I, and B lineage (one third); cells from 62% of these ALL cases coexpressed other myeloid markers (CD13, CD33, or both). There were no differences in the frequency of c-kit+ AML or ALL cases according to age being similar in the adult and pediatric groups. Our findings demonstrate that c-kit is a reliable and specific marker to detect leukemia cells committed to the myeloid lineage, and therefore should be included in a routine basis for the diagnosis of acute leukemias to demonstrate myeloid commitment of the blasts. c-kit expression should score higher, at least one point, in the system currently applied to the diagnosis of BAL, as its myeloid specificity is greater than CD13 and CD33. Findings in ALL and AUL suggest that c-kit identifies a subgroup of cases, which may correspond to leukemias either arising from early prothymocytes and/or early hematopoietic cells, both able to differentiate to the lymphoid and myeloid pathways.     

Infrequent alterations of the RAR alpha gene in acute myelogenous leukemias, retinoic acid-resistant acute promyelocytic leukemias, myelodysplastic syndromes, and cell lines

Retinoids are important regulators of cell growth and differentiation in vitro and in vivo and they exert their biologic activities by binding to nuclear retinoic acid receptors (RARs; alpha, beta, and gamma) and retinoid X receptors (RXRs; alpha, beta, and gamma). All-trans retinoic acid (RA) induces complete remission in patients with acute promyelocytic leukemia (APL) presumably by binding directly to RAR alpha of APL cells. Leukemic blasts from APL patients initially responsive to RA can become resistant to the agent. HL-60 myeloblasts cultured with RA have developed mutations of the ligand-binding region of RAR alpha and have become resistant to RA. Furthermore, insertion of an RAR alpha with an alteration in the ligand-binding region into normal murine bone marrow cells can result in growth factor-dependent immortalization of the early hematopoietic cells. To determine if alterations of the ligand binding domain of RAR alpha might be involved in several malignant hematologic disorders, the mutational status of this region (exons 7, 8, and 9) was examined in 118 samples that included a variety of cell lines and fresh cells from patients with myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML), including 20 APL patients, 5 of whom were resistant to RA and 1 who was refractory to RA at diagnosis, using polymerase chain reaction-single-strand conformational polymorphism (PCR-SSCP) analysis and DNA sequencing. In addition, 7 of the 20 APLs were studied for alterations of the other coding exons of the gene (exons 2 through 6). No mutations of RAR alpha were detected. Although the sensitivity of PCR-SSCP analysis is less than 100%, these findings suggest that alterations of RAR alpha gene are rare and therefore other mechanisms must be involved in the onset of resistance to retinoids and in the lack of differentiation in disorders of the myeloid lineage.     

The clinico-morphological characteristics of myeloid leukemias under the current ecological conditions in Ukraine]

BACKGROUND: The prerequisite of effective haemodialyzation treatment is prevention of blood coagulation in the extracorporeal circulation. The objective of the study was to evaluate the effectiveness, safety and dosage of low-molecular heparin nandroparinum calcium--Fraxiparine (Sanofi) in haemodialyzation treatment of adult patients. METHODS AND RESULTS: In 29 patients (22 men, 7 women, age 54 +/- 12 years) a total of 2125 haemodialyses were made on a capillary dialyzer with a cuprophane membrane extending over 3.6 +/- 0.5 hours, incl. 84 (9 subjects) with acute and 2041 (20 subjects) with chronic irreversible renal failure. In none of the procedures complete coagulation occurred, partial coagulation of the dialyzer or the presence of fibrin deposits in the return line was found only in 148 (7%) haemodialyses, statistically significantly more frequently in acute procedures (48; 57%; p < 0.01), as compared with chronic procedures (100; 5%). The authors did not observe any haemorrhage during or after haemodialysis. The total dose of Fraxiparine needed in acute dialyses was higher (6900 +/- 2400 U.I. aXa) as compared with chronic procedures (5400 +/- 1700 U.I. aXa) the difference is however not statistically significant. In 1910 haemodialyses (89.9%) only a single bolus dose was used 5100 +/- 1400 U.I. aXa Fraxiparine (70 U.I./kg). CONCLUSIONS: Low-molecular heparin Fraxiparine administered as a bolus makes safe and effective anticoagulation during haemodialysis possible and does not call for laboratory follow-up of the anti-Xa level. In acute haemodialyses larger doses are needed.     

Impact of in vivo administration of interleukin 3 on proliferation, differentiation, and chemosensitivity of acute myeloid leukemia

Early clinical trials of growth factor augmentation of induction chemotherapy for acute myeloid leukemia have yielded variable results. To test the hypothesis that this heterogeneity is a consequence of the pleiotropic effects of growth factors on leukemic cell biology, we measured the effects of in vivo interleukin 3 (IL-3) administration on leukemic cell proliferation and drug sensitivity. Thirty-four patients with acute myeloid leukemia with high-risk features or advanced myelodysplasia received IL-3 as a continuous infusion beginning 3 days prior to chemotherapy and continuing for the duration of intensive induction therapy. Bone marrow cells were studied prior to and after 3 days of IL-3 administration to assess changes in overall and leukemic progenitor cell [leukemia colony-forming unit (CFU-L)] proliferation, and progenitor cell sensitivity to 1-betad-arabinofuranosylcytosine. The median fold increase in overall leukemic cell proliferation in response to IL-3, assessed as expression of the nuclear antigen Ki67 in 28 patients, was 1.2. The median fold increase in percentage of cells in S phase (assessed in 29 patients) was 1.3. Despite the increase in overall cell proliferation in 70% of cases, CFU-L number increased in only 4 of 20 patients successfully studied (median day 4:day 1 ratio of CFU-L number, 0.6). While this suggests possible terminal differentiation of leukemic progenitor cells, expression of CD34, HLA-DR, c-kit, CD15, and CD14 were not consistently affected by the cytokine. 1-betad-Arabinofuranosylcytosine sensitivity of CFU-L increased significantly in 30% of cases, decreased in 30%, and was unchanged in 40%. Changes in overall cell proliferation (Ki67 expression) and CFU-L were independent predictors of change in 1-beta-d-arabinofuranosylcytosine sensitivity; increase in percentage of cells in S phase in response to IL-3 was correlated with attainment of complete remission. While these findings support the concept of cell cycle recruitment, IL-3 has marked pleiotropic effects on proliferation, differentiation, and survival of leukemic progenitors which make the clinical impact of in vivo cytokine administration for individual patients difficult to predict.     

Structure and function of the long terminal repeats of feline leukemia viruses derived from naturally occurring acute myeloid leukemias in cats

Long terminal repeats of feline leukemia viruses cloned from feline acute myeloid leukemias frequently contained direct repeats of 40 to 74 bp in the upstream region of the enhancer (URE). The repetitive URE conferred an enhancer function upon gene expression in myeloid cells, suggesting its association with tumorigenic potential in myeloid cells.     

An evaluation of the usefulness of amylase isozyme differentiation in patients with hyperamylasemia

Amylase assays measure total activity without differentiating the relative contributions of pancreatic- and salivary-type amylase isozymes. Since polyacrylamide electrophoresis allows identification of salivary-and pancreatic-type isoxymes and their respective variants, serum and urine specimens from patients with the clinical diagnoses of mumps (4), pancreatitis (16), or undiagnosed hyperamylasemias (5) were compared with specimens from control subjects. Patients with mumps had elevations of salivary-type isozymes, while those with pancreatitis had elevations of pancreatic-type isozymes. Elevation of salivary-type isozymes was identified in the five patients who had undiagnosed hyperamylasemias; among these, the isozymes of two originated in neoplastic ovarian tissue and those of three, probably in the salivary glands. Amylase isozyme differentiation cannot unamibiguously identify the tissue source of hyperamylasemia. However, in patients whose hyperamylasemia is of unknown etiology or who respond atypically to therapy, amylase electrophoresis provides identification of the elevated isozyme type, thus providing the basis for the rational selection of further diagnostic procedures.     

Functional expression of Fas (CD95) in acute myeloid leukemia cells in the context of CD34 and CD38 expression: possible correlation with sensitivity to chemotherapy

Clinical studies of bone marrow transplantation (BMT) suggest that the immune system contributes to the eradication of acute myeloid leukemia (AML). A recent study also showed that the Fas (CD95/APO1) mediates apoptotic signal from cytotoxic T lymphocytes. Sixty-four patients with AML were studied for the expression of Fas in the context of CD34 and CD38 coexpression. The clinical relevance of Fas expression and function on AML was also investigated. Fas was expressed on 2% to 98% of AML cells (2% to 20% in 11 patients, 20% to 50% in 20 patients, 50% to 80% in 24 patients, and 80% to 98% in nine patients). Only 44.4% of patients with AML M1 (French-American-British [FAB] classification) were Fas+ (>/=20% of leukemia cells expressed Fas), whereas 89.1% of patients with AML M2, M3, M4, M5 were Fas+ (P < .01). Among 43 CD34+ patients (>/=20% leukemia cells were CD34+), 34 were Fas+, and 19 of 21 CD34- patients were Fas+ (P = NS). Thirteen cases were studied for their expression of Fas in the context of CD34 and CD38 using three-color analysis. Fas is expressed at a high level in the gated CD34+CD38+/- and CD34+CD38+ population. In 10 AML samples, Fas was expressed at a higher level in CD34+/CD38+ population than in CD34+/CD38+/- or CD34- cell populations. Fas-induced apoptosis by anti-Fas monoclonal antibody (MoAb) was determined by morphologic features and colorimetric DNA fragmentation assay. Induction of apoptosis was found in 14 of 24 cases. However, no statistically significant correlation was observed between Fas expression and induction of apoptosis. Leukemia colony-forming unit assays suggested that in some cases, Fas-induced apoptosis occurred in the clonogenic cell populations. Parameters such as laboratory and clinical data at initial diagnosis were correlated with Fas expression and only response to initial induction chemotherapy showed significant correlation with Fas expression (P < .05). We conclude that the majority of AML cells exhibit variable expression of Fas, and apoptosis could be induced by anti-Fas MoAb in some cases. Our results suggest the Fas-mediated apoptosis may be clinically relevant, whereas the issue of clonogenic leukemia cells and Fas expression needs further studies.     

High bcl-2 expression in acute myeloid leukemia cells correlates with CD34 positivity and complete remission rate

Flow cytometric expression of bcl-2 protein was analyzed in 90 newly diagnosed acute myeloblastic leukemia (AML) patients using an anti-bcl-2 monoclonal antibody by direct immunofluorescence technique and results were correlated with FAB cytotype, CD34 expression and clinical outcome. Bcl-2 was expressed in all AML cases with different intensity. The mean fluorescence index (MFI), expressed as the ratio of sample mean channel:control mean channel, ranged from 3.0 to 39.5 with a median value of 14. The MFI was significantly higher (P = 0.01) in M0 (20.9) and M1 (18.3) than in M2 (11.7), M3 (12.4), M4 (11.8) and M5 (9.5) cytotypes. In addition, bcl-2 MFI significantly correlated both with CD34 positivity (P = 0.001) and with CD34 MFI (P = 0.01), being CD34 antigen expressed in 65% of patients with a bcl-2 MFI >14, and only in 35% of AML cases with a bcl-2 MFI >14. When bcl-2 intensity expression was correlated with complete remission (CR) rate, a higher MFI was associated with a low CR rate after standard intensive chemotherapy. In particular, CR was achieved in 86% of patients with a bcl-2 MFI <14, but only in 57% of patients with a MFI >14 (P = 0.008). A further decrease of CR rate to 41% was observed in patients in whom a higher bcl-2 MFI was coupled with the presence of CD34 antigen on their blasts. By statistical analysis we also demonstrated that both bcl-2 high MFI (>14) and CD34 expression are independent prognostic factors for achieving CR in AML. These data raise the hypothesis that high values of bcl-2 may confer on myeloid blasts a higher resistance to standard chemotherapy. However, identification of patients with high expression of bcl-2 may be important for a different therapeutic approach.     

Functional CD4+ T cell subsets defined by expression of CD45RC and NTA260 antigens and age-associated polarization in murine lupus

Using two mAb, one specific to the alternative exon 6-dependent epitope of CD45 molecules (JH6.2) and one a natural thymocytotoxic autoantibody (NTA) with an unknown reactive epitope (NTA260), we subdivided splenic CD4+ T cells from 2-month-old BALB/c mice into five phenotypically distinct subsets. CD45RC+NTA260- (S I) cells were phenotypically analogous to CD4+ T cells predominating in newborn mice and produced a significant amount of IL-2, but not so IL-4, IL-10 or IFN-gamma when stimulated with immobilized anti-CD3 mAb in vitro. They appeared to consist mainly of naive ThP cells. The CD45RC+NTA260+ (S II) subset also produced IL-2, but not other cytokines; however, the IL-2 levels produced were much higher than seen with the S I subset, thereby suggesting the predominance of further maturated ThP cells. The CD45RC-NTA260+ (S III) subset mainly produced IL-4, IL-10, IFN-gamma and less IL-2, and contained memory cells that helped the secondary antibody response to a recall antigen, and hence contained Th2 and probably a mixture of Th0 and Th1 cells. The CD45RC-NTA260- (S IV) subset was a poor responder to the immobilized anti-CD3 mAb. The CD45RCbrightNTA260dull (S V) subset consisted of a small number of cells that were phenotypically analogous to activated CD4+ T cells. While an age-associated decrease in the proportion of S I and less markedly in S II and in turn increase in S III subsets of CD4+ T cells occurred in normal BALB/c mice, autoimmune disease-prone (NZB x NZW)F1 mice showed a marked age-associated decrease in the proportion of not only S I, II but also III subsets. As aged (NZB x NZW)F1 mice carry CD4+ T helper cells for IgG anti-DNA antibody production, such age-associated polarization to the S IV subset appears to be critical in the pathogenesis of autoimmune disease in these mice.     

The expression of CD26 and CD40 ligand is mutually exclusive in human T-cell non-Hodgkin's lymphomas/leukemias

CD26 and CD40 ligand (CD40L) are surface molecules on human activated T lymphocytes that play a critical role in the regulation of lymphopoiesis. Both molecules are expressed on a restricted fraction of human T-cell non-Hodgkin's lymphomas (NHL)/leukemias; however, little is known about their functional and/or clinical significance in these disorders. In this study, the pattern of expression of CD40L was compared with that of the CD26 molecule. A series of 67 human T-cell NHL/leukemias and a panel of leukemia/lymphoma T-cell lines were evaluated by immunohistochemistry, flow cytometry, and RNA studies. The overall frequency of CD26+ and CD40L+ samples was rather similar (25/67 [37%] v 18/67 [27%]). However, the majority of CD26-expressing cases clustered in the lymphoblastic lymphomas (LBL)/T-acute lymphoblastic leukemias (ALL; 12/23) and CD30+ anaplastic large-cell (ALC) lymphomas (5/8), whereas CD40L+ lymphomas included a large fraction of mycosis fungoides (11/21 [52%]). CD26 and CD40L coexpression was found only in 2 myocosis fungoides cases and 1 small lymphocytic lymphoma. Thus, the expression of the two antigens was mutually exclusive in almost all T-cell lymphomas/leukemias. Accordingly, lymphoma cell lines expressed either one of the molecules or the relative amounts of CD26 and CD40L were inversely proportional. In contrast, reactive T lymphocytes from patients with non-neoplastic T-cell expansions and in vitro activated CD3+ or CD4+ normal T cells were found to coexpress CD40L and CD26. Results of a multivariate analysis showed that the expression of CD26 in T-cell LBL/ALL patients was associated to a worse outcome in terms of survival, as compared with patients with CD26- tumors (P < or = .0001). Based on our results, it can be concluded that, (1) as opposed to activated or reactive normal T cells, the expression of CD26 and of CD40L is mutually exclusive in human T-cell lymphomas/leukemias; (2) expression of CD26 is restricted to aggressive pathologic entities, such as T-cell LBL/ALL and T-cell CD30+ ALC lymphomas, whereas CD40L is expressed on slow progressing diseases such as mycosis fungoides; and (3) within the T-cell LBL/ALL group of tumors, CD26 may identify a subset of poor prognosis patients.     

The role of decreased retinoblastoma protein expression in acute myelomonocytic and monoblastic leukemias

The results of different investigators show that lack of p105 expression is relatively common in human myeloid leukemias, especially in monocytic leukemias. This suggests that loss of p105 expression could contribute to the altered growth control of these cells. So far no clear data exist which show that low p105 levels in AML blasts predict a poor therapy outcome. Therefore it is not very likely that p105 expression will become a strong prognostic factor for the different treatment strategies in AML.     

The empirical antibiotic therapy of patients with acute leukemias: the results of a multicenter study

AIM: To evaluate efficacy of ampicilline/sulbactame and fluconasole in the regimen of empirical antibiotic therapy in patients with acute leukemia. MATERIALS AND METHODS: The trial covered 14 hematological departments of Russia and 1 of Ukraine. Acute myeloid leukemia patients were included. 92 cases of fever in 56 patients with analysis of efficacy in 66 cases were considered. At the first stage of empirical antibiotic therapy, cefoperason (4 g/day) and gentamycin (240 mg/day) were administered. If no response was reached, ampicilline/sulbactam (7.5 g/day) was added. This was the second stage. If no response occurred for 5 days the three drugs were joined by fluconasol (400 mg followed by 200 mg). RESULTS: Fever of unclear genesis was cured in 82% (28 of 34), clinical infection--in 80% (20 of 25), microbiologically confirmed infection--in 4 of 7 cases. A complete response to the empirical antibiotic therapy was registered in 52 of 66 cases (79%). 7(10.5%) patients died of infectious complications. 7(10.5%) received other antibiotics.     

The levels of memory (CD45RA-, RO+) CD4+ and CD8+ peripheral blood T-lymphocytes correlate with IgM rheumatoid factors in rheumatoid arthritis

We investigated whether, in rheumatoid arthritis (RA), the CD45 isoform expression of peripheral blood T-lymphocytes (T-PBL) is related to auto-immune processes (e.g. IgM rheumatoid factors) and to clinical manifestations. By three-colour flow cytometry, we quantified three subsets of CD4+ or CD8+ T-PBL: naive CD45RA+,RO-, transient CD45RA+,RO+, and memory CD45RA-,RO+ cells, in 102 patients with RA and in 41 age- and sex-matched controls. The serum levels of rheumatoid factors (RF) were determined--besides conventional agglutination tests--by ELISA (IgM-RF). Extensive clinical examination was performed at the time of blood sampling. In RA, age, sex and drug therapy did not constitute major influences on the CD45RA/RO patterns. In healthy men, higher age significantly' correlated with fewer naive and more memory CD4+ T-PBL (P < 0.01). In RA, distinct correlations between the T-PBL subsets, autoimmune and clinical manifestations became obvious when patients with low and high levels of RF against human IgG Fc fragments, as determined by ELISA, were analysed separately. RA patients with high IgM-RF had elevated proportions of CD45RO+ T-PBL (P < 0.05), that correlated with clinical parameters of disease activity (tender joint count, Ritchie index, P < 0.05) and outcome (Health Assessment Questionnaire, Larsen radiographic scores, P < 0.05). The proportions of memory CD4+ and CD8+ T-PBL correlated strongly (P < 0.001) with the IgM-RF levels. Within 1 year, only three of 34 patients (disease duration of 5-9 years) showed seroconversion from low to high levels of IgM-RF (and positive agglutination tests); this was paralleled by reductions in naive and increases in transient T-PBL (P < 0.02). Thus, in RA, the proportions of memory CD4+ and CD8+ T-PBL correlate with the level of IgM-RF and, together with transient T-PBL, with clinical parameters of disease activity and outcome.     

Inhibition of the progression of multiple sclerosis by linomide is associated with upregulation of CD4+/CD45RA+ cells and downregulation of CD4+/CD45RO+ cells

In a recent double-blind, phase II study, conducted in our department, we showed that Linomide-treated MS patients had significantly less active lesions (in serial monthly MRI tests) and a tendency for clinical stabilization. Here we present the immunological evaluation of the patients who participated in this study and propose a novel mechanism by which Linomide downregulates autoreactivity. Peripheral blood leukocytes (PBLs), serum, and CSF samples were obtained at two to four time points over the 6 months of the trial. Flow cytometric analysis (FACS) of the CD5/CD19, CD4/CD8, CD14/CD3, CD16/CD3, CD45RA/CD4, and CD45RO/CD4 surface markers on PBLs was performed and the levels of the IL-1beta, IL-2, IL-4, IL-6, IL-10, TNF-alpha, IFN-gamma, and IL-2R were also examined. White blood counts of Linomide-treated patients were consistently elevated throughout the treatment period (P = 0.002-0.04). Cytokines levels in serum and CSF were highly fluctuating and we could not detect any clear trend as a result of Linomide treatment. FACS analysis showed that Linomide treatment significantly increased the percentage of the CD4+/CD45RA+ cells (from 35.5% at baseline to 42.3% at week 24; P = 0.02), and decreased CD4+/CD45RO+ lymphocytes (62.6% at baseline vs 53.7% at week 24, P = 0.02). Linomide also induced a transient increase in the NK-cells, the NK 1.1 cells, and the CD5 B-cells (P = 0.02). Upregulation of naive CD45RA T-lymphocytes and parallel downregulation of memory CD45RO cells seems to be one of the main mechanisms by which Linomide inhibits MS activity and may represent an alternative immunomodulating approach for the treatment of MS and autoimmunity in general.     

Effects of mast cell growth factor on acute myeloid leukemia cells in vitro: effects of combinations with other cytokines

We have investigated the stimulative effects of mast cell growth factor (MGF) in primary acute myeloid leukemia (AML) in vitro. MGF stimulated DNA synthesis of purified leukemic blasts in eight out of 10 cases and colony formation in four cases in serum-free (SF) culture. MGF synergized with interleukin-3 (IL-3; four out of 10 cases), granulocyte-macrophage colony-stimulating factor (GM-CSF; three out of 10 cases), granulocyte colony-stimulating factor (G-CSF; six out of 10 cases), macrophage colony-stimulating factor (M-CSF; one out of 10 cases) and erythropoietin (EPO; one out of 10 cases) when added to culture in combination. Synergistic effects of MGF in combination with other CSFs were also seen in the colony assay. Antibodies against GM-CSF, M-CSF, G-CSF, and IL-6 did not inhibit the MGF response, suggesting that the stimulative effect of MGF was not mediated through autocrine release of those cytokines. Cell recovery data in liquid cultures that contained MGF, IL-3, or MGF + IL-3, indicated that both MGF and IL-3 augmented the maintenance of clonogenic cells as compared to nonsupplemented cultures, but the effect of the combination of IL-3 + MGF did not show synergy. In contrast, activation of DNA synthesis by MGF was abrogated in the presence of tumor necrosis factor (TNF; four out of 10 cases) and interleukin-4 (IL-4; two out of 10 cases). Fluorescence-activated cell sorting (FACS) analysis with anti c-kit antibodies revealed MGF receptor expression in eight out of nine cases, often in a subpopulation of the cells. Scatchard analysis of MGF receptors in two cases indicated the presence of 1460 and 41,500 (mean) binding sites, respectively, of high affinity (Kd 40-160 pmol/l). The MGF dose-response curve in the presence of IL-3 or GM-CSF resulted in a higher plateau of DNA synthesis, however no shift in the dose response was apparent. The respective reciprocal dose response relations to GM-CSF, IL-3, or G-CSF were similarly elevated when MGF was added. MGF did not alter IL-3 and GM-CSF receptor expression, nor did IL-3, GM-CSF, G-CSF, TNF, or IL-4 influence MGF binding to AML cells.(ABSTRACT TRUNCATED AT 400 WORDS)