Biomedical subjects

D Flieger

Publications and source records attributed to D Flieger.

26 records · Page 2Linked to original sources

PubMed1990

[Interferon alfa-2B in chronic lymphatic leukemia of the B-cell type].

In a clinical phase II study nine patients (five men and four women; mean age 48 [42-58] years) in an early stage of chronic lymphatic leukaemia (CLL) of the B-cell type were treated with recombinant alpha-2b interferon (IFN alpha-2b), initially at a dosage of 5 mega units subcutaneously three times weekly, but in some cases reduced to 2.5 or raised to 10 mega units. Duration of treatment has been 15-36 months. Through-flow cytometry in seven patients demonstrated a definite fall in circulating B1-positive lymphocytes. Lasting partial remission (duration of 106-134 weeks) was achieved in four patients, in a further four the condition remained stable. A recurrence was noted in the patient with the initially highest lymphocyte count (52,000/microliters) after 28 weeks, control being achieved only after 64 weeks of chemotherapy. Side effects were flu'-like symptoms and (in two instances) depression. In three patients there was a clear rise in serum immunoglobulin concentrations as sign of IFN alpha-2b-induced increased immune response, while in four HLA-DR expression on monocytes was doubled. It is concluded that early treatment of CLL with IFN alpha-2b may delay the onset of necessary chemotherapy, any antibody-deficiency may be improved and survival time may ultimately be lengthened.

Adult↗

PubMed1990

Deficient production of tumor necrosis factor by peripheral-blood monocytes in chronic lymphocytic leukemia.

The production of tumor necrosis factor (TNF) by lipopolysaccharide (LPS)-triggered peripheral-blood mononuclear cells (PBM) was investigated in 23 patients with untreated B-cell chronic lymphocytic leukemia (B-CLL) and 14 control donors. Cells were stimulated at concentrations that reflect cell density in peripheral blood. Under these conditions, PBM from 11/23 of the CLL patients produced at least 10-fold less TNF as compared with controls. Monocyte numbers were decreased in percentage, while absolute numbers (normal range 233 +/- 120 X 10(3)/mm3) were decreased only in 2, normal in 17 and increased in 4 patients indicating that the deficiency is not a result of monocytopenia in most patients. Cell separation experiments indicate that after removal of leukemic B cells, percentages of monocytes return to control range and TNF production is improved (7/7). In mixing experiments, we found a suppression of TNF production in control mononuclear cells by CLL cell samples (75 X 10(6) cells/ml) in 5/19 cases, while control cells from thymus exhibited no or little suppression in these conditions. In 2-chamber experiments, leukemic samples suppress TNF production by normal monocytes across a 0.45 micron membrane indicating that a soluble factor is responsible for suppression. The factor exhibits higher stability in serum-free conditions and its molecular weight is below 20 kDa. Prostaglandins are not involved, since indomethacin did not abrogate suppression.

Aged↗

PubMed1989

Identification and characterization of a novel monocyte subpopulation in human peripheral blood.

With the aid of two-color immunofluorescence and flow cytometry, a new subset of cells coexpressing CD14 and CD16 antigens can be identified in human peripheral blood. Using the monoclonal antibody My4, these CD14+/CD16+ cells account for 2.2% of the mononuclear cells and form about 13% of all cells identified by the monocyte-specific CD14 monoclonal antibody. The CD14+/CD16+ cells can be assigned to the monocyte lineage based on typical morphology, on expression of additional monocyte-associated molecules, on the ability to form reactive oxygen intermediates and on the expression of monocyte-specific NaF-sensitive esterase. Light scatter analysis revealed lower forward angle and right angle light scatter for the CD14+/CD16+ cells compared with the regular monocytes, and the average cell size was determined to be 13.8 and 18.4 microns, respectively. Expression of class II antigens on these "small monocytes" was twofold higher compared with the regular monocytes. By contrast, the capacity to perform adherence to plastic surfaces, as well as the ability to phagocytize antibody-coated erythrocytes was clearly reduced in the CD14+/CD16+ monocyte subset as compared with the regular monocytes. Hence the CD14+/CD16+ cells appear to represent a new monocyte subset with a distinct functional repertoire. A survey of various tissues revealed that a large proportion of the alveolar macrophages, but not of the peritoneal macrophages, express the CD14+/CD16+ phenotype.

Antibodies, Monoclonal↗

PubMed1989

Zn++ inhibits both tumor necrosis factor-mediated DNA fragmentation and cytolysis.

The cellular events involved in direct tumor-cell destruction by tumor necrosis factor (TNF) are still incompletely understood, but a role of endonucleases has been suggested. In the present study we have analyzed in detail the effect of Zn++, an inhibitor of endonucleases, on TNF-mediated DNA-fragmentation and on cytolysis in Actinomycin-D-pre-treated WEHII 64-S cells. Beginning 2 hr after addition of TNF, a rapid degradation of cellular DNA is observed, as evidenced by release of 3H-Thymidine (TdR) label from nuclei into cytoplasm. TNF-mediated lysis of WEHII64-S cells begins at 3 hr and reaches plateau levels at 7 hr. Addition of Zn++ to TNF-treated WEHII64 cells completely abrogates DNA fragmentation at ImM. Of greater importance is the fact that Zn++ treatment also completely blocks TNF-mediated cytolysis of the target cells. Concentrations-between 0.1 and I mM ZnSO4 prevent cell death, as assessed by chromium-release and Trypan blue dye exclusion. In addition, ZnCl2, but not other divalent cations like CaCl2, MgSO4 and CuSO4 in the same concentration range, prevents cell death as well, demonstrating that the effect in fact is mediated by Zn++. Zn++ added 2 hr after TNF treatment, still effectively inhibits cell lysis, indicating that it acts at a late stage after binding of TNF to its receptor. Our data suggest that activation of endonucleases is not an accompanying effect but an essential step in TNF-mediated tumor-cell destruction.

Animals↗

PubMed1989

Favorable response of early stage B CLL patients to treatment with IFN-alpha 2.

Since interferon (IFN-alpha) treatment has proven effective in hairy cell leukemia, its evaluation in chronic lymphocytic leukemia (CLL), a cytologically related disease, appeared reasonable. In our study, we have focused on previously untreated, early stage patients who are less than 60 years of age. All patients had less than 50,000 lymphocytes/microL and immunologic analysis revealed a CD20+, IgM+, IgD- phenotype for leukemic B cells in eight of nine patients. Recombinant interferon alpha 2b (IFN-alpha 2) at 5 x 10(6) U was given subcutaneously three times per week for 8 to 16 months. Consistent with earlier reports, side effects were minor with this low-dose protocol. All patients responded with a decrease of WBC count and lymphocyte count; in one patient, splenomegaly resolved such that he moved from Rai stage II to Rai stage I. On the average CD20+ B cells decreased from 14,312 to 3,995 cells/microL, indicating that no complete eradication of the leukemic cells was possible. A partial response, based on a greater than 50% reduction of CD20+ B cells was obtained in five of seven patients analyzed. The increased numbers of CD2+ T lymphocytes decreased in response to interferon treatment in six of seven patients. Furthermore, in a portion of the patients class II antigen expression was enhanced on LeuM3+ monocytes suggesting an in vivo activation of the monocytes by IFN-alpha 2. Immunoglobulin levels were substantially improved in that serum IgG increased by more than 3 g/L in three of seven patients. In one patient, lymphocyte counts increased in spite of continued therapy, whereas all others exhibited no increase of lymphocyte numbers while on therapy. Our study clearly demonstrates effects of IFN-alpha 2 treatment on both the leukemic cells and on the nonleukemic components of the immune system in peripheral blood. Whether IFN-alpha treatment will result in long-term beneficial effects in early stage CLL needs to be evaluated in a larger study.

Antigens, Differentiation↗

PubMed1988

Abnormal blood monocytes in chronic lymphocytic leukemia.

Blood monocytes were analyzed in 28 patients with chronic lymphocytic leukemia without previous cytotoxic therapy and without recent infection. Using monoclonal antibodies and flow cytometry, monocytes identified by LeuM3 or My4 were low in percentage (2.3%), but absolute numbers were increased in many patients with values exceeding the normal range (120 to 510/microliter) in seven of 28 patients. Monocytosis was more prominent in patients with high leukemic counts, but there was no correlation to clinical stages. Monocytopenia was evident with less than 50 LeuM3+ cells/microliter in three patients. Two-color fluorescence was used for the analysis of cell surface expression of major histocompatibility complex (MHC) Class II molecules, complement receptors, and Fc receptors on the LeuM3+ monocytes. Compared to cells from control donors, there was an increase for MHC class II antigens, complement receptors, and Fc receptors on the monocytes in chronic lymphocytic leukemia, in terms of both the percentage of positive cells among the LeuM3+ monocytes and of fluorescence intensity. This increase was not restricted to patients with monocytosis nor were the molecules always upregulated concomitantly. The increase of antigen expression on LeuM3+ monocytes was more than 50% (1.5-fold) in seven of 22 patients for MHC Class II antigens, in seven of 16 patients for complement receptor and in six of 12 patients for Fc receptor. A similar decrease of antigen expression was observed only in one patient for MHC Class II and in one patient for complement receptor expression. Monocytosis and increased expression of monocyte cell surface antigens described for a large portion of patients might be causally involved in the immunodeficiency in chronic lymphocytic leukemia.

Aged↗

PubMed1988

The monoclonal antimonocyte antibody My4 stains B lymphocytes and two distinct monocyte subsets in human peripheral blood.

The monoclonal antibody (MAB) My4 was produced against human myelo-monocytic leukemia cells and stains regular monocytes with high intensity. Employing logarithmic amplification in immunofluorescence flow cytometry an additional low intensity - My4+ - and a very low intensity population - My4(+) - can be identified. Light scatter analysis reveals monocyte features for the My4++ and for the My4+ cells, while the My4(+) cells exhibit characteristics of lymphocytes. The two low intensity (My4+ and My4(+)) populations are clearly discernable only after two color immunofluorescence analysis using MABs VEP13 (CD16) and B1 (CD20). The My4+ cells coexpress the CD16 antigen and comprise a unique monocyte subset. The My4(+) cells coexpress the B1 antigen, characteristic of B cells. In addition, the My4(+) cells are depleted after treatment of mononuclear cells with the anti-B cell MAB BA-1 plus complement. Finally, leukemic cells from patients with B cell type chronic lymphocytic leukemia are stained in 18/20 cases. Hence, the MAB My4 identifies regular monocytes and in addition, with lower intensity of staining a new monocyte subset and a subset of B cells in human peripheral blood.

Antibodies, Monoclonal↗

PubMedDate not supplied

Augmentation of 17-1A-induced antibody-dependent cellular cytotoxicity by the triple cytokine combination of interferon-alpha, interleukin-2, and interleukin-12.

Previously, interferon-alpha (IFN-alpha), interleukin-2 (IL-2), and interleukin-12 (IL-12) were shown to increase the antibody-dependent cellular cytotoxicity (ADCC) induced by the murine monoclonal antibody 17-1A, which recognizes the tumor-associated antigen EpCAM. In this study, the authors wanted to determine whether the combination of these three cytokines would yield greater cytotoxicity than the single cytokines. For cytotoxicity assessment, a new flow cytometric assay was used that allows the analysis of long-term ADCC exerted by macrophages. Peripheral blood mononuclear cells from healthy donors were used as effector cells against the colorectal carcinoma cell line HT29 at a low effector-to-target ratio of 4.5:1. With this test, the effectiveness of the combinations IL-2 and IFN-alpha, IL-2 and IL-12, and IL-12 and IFN-alpha were compared with each other. The combinations IL-2 plus IL-12 and IFN-alpha plus IL-12 were more potent at the concentrations tested. Furthermore, the triple cytokine combination of IFN-alpha, IL-2, and IL-12 revealed significantly greater ADCC than dual cytokine combinations. Next, CD14+, CD4+, and CD4- cells were isolated by paramagnetic beads and magnetic activated cell sorter (MACS) columns. The CD14+ and CD4- cell populations contained the ADCC effectors. The addition of CD4+ cells to CD14+ or CD4- cells resulted in augmented ADCC, indicating that cooperation between immune cells occurs. These results suggest that multiple cytokine combinations with monoclonal antibodies may be more effective for cancer immunotherapy.

Adenocarcinoma↗