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A Degrassi

Publications and source records attributed to A Degrassi.

At least 37 records · Page 2Linked to original sources
PubMed1994

Transfer of HIV-1 to human tonsillar stromal cells following cocultivation with infected lymphocytes.

The susceptibility of normal human tonsillar stromal cells (HTSCs) to infection by HIV-1 was assessed using transmission electron microscopy (TEM), immunocytochemistry, and HIV-1-specific PCR analyses. Our results demonstrate that HTSCs are efficiently infected following cocultivation with the HIV-1-infected lymphoblastoid cell line GY1. Infected stromal cells contain intracellular viral particles present as free virus or associated with phagocytic vesicles. These particles express the HIV-1-specific p24 antigen as assessed by immunocytochemical analyses using an HIV-specific anti-p24 monoclonal antibody. Moreover, PCR analysis of genomic DNA isolated from particle-bearing tonsillar stromal cells identified HIV-1-specific sequences not present in either uninfected stromal cells or parental GY1 uninfected cells. The mechanism by which HIV-1 infects HTSCs does not appear to be CD4 mediated, as none of the human tonsillar stromal cell lines express CD4 as assessed by flow cytometry, immunohistochemistry, and PCR analysis. Taken together, these results demonstrate that human tonsillar stromal cells can be infected by HIV-1, and that subsequent to infection the viral genome is reverse transcribed, and integrated into the stromal cell DNA. The infection of HTSCs may contribute to HIV-1-mediated pathogenesis indirectly as a viral reservoir or directly by structural and functional modification of the lymphoid microenvironment.

Antibodies, Monoclonal↗
PubMed1993

In vitro culture of primary plasmacytomas requires stromal cell feeder layers.

Attempts to grow primary murine plasmacytomas in vitro have, to date, been largely unsuccessful. In this study, we demonstrate that long-term in vitro growth of primary plasmacytomas is accomplished by using feeder layers composed of stromal cells from the initial site of plasmacytomagenesis. The early neoplastic lines established in this manner are dependent on physical contact with the stromal layer, which is mediated in part by CD44, for growth and survival. The stromal cells provide at least two stimuli for the plasma cells, one being interleukin 6 and the second, of unknown nature, resulting from direct physical interaction that cannot be replaced by soluble factors. These plasma cell lines have been passaged for as long as 20 months yet still maintain characteristics associated with primary plasmacytomas as they will grow in vivo only in pristane-primed animals, indicating a continued dependence on the pristane-induced microenvironment characteristic of early-stage tumors. The ability to grow primary plasmacytomas in culture and maintain their "primary" properties provides a model system for detailed analysis of early events in plasma cell tumor progression involving neoplastic cells completely dependent on physical contact with a stromal feeder layer for survival and expansion.

Animals↗
PubMed1993

Pristane induces an indomethacin inhibitable inflammatory influx of CD4+ T cells and IFN-gamma production in plasmacytoma-susceptible BALB/cAnPt mice.

In BALB/cAnPt (BALB/c) mice, the intraperitoneal injection of pristane induces the formation of chronic oil granulomatous tissue and a high incidence of plasmacytomas (PCT). DBA/2N (DBA) and (BALB/c x DBA)F1 hybrid (CDF1) mice develop oil granulomas but no PCT. Recent studies comparing pristane-injected conventionally housed BALB/c mice with specific pathogen-free BALB/c mice (SPF) demonstrated a significant reduction in both the incidence of PCT and the T cell infiltration of oil granulomatous tissue in SPF mice. In this study, FACS analysis was performed to determine the proportion of myeloid, T. and B cells present in pristane-induced peritoneal exudate (PE), and oil granulomas (OG) of BALB/c, DBA, and CDF1 mice. At all time points studied, the majority of cells recovered from the PE and OG of all three strains of mice were Mac-1+, presumably macrophages and neutrophils. Neither Ly-5(B220)+ B cells nor CD8+ T cells were significantly altered by pristane injection. BALB/c mice had a dramatic influx of CD4+ T lymphocytes (three- to fivefold) more than 50 days after the initial injection of pristane. The PCT-resistant DBA and CDF1 mice did not. This increase in CD4+ cells in BALB/c mice was not significantly affected by a second injection of pristane nor was it induced by a second injection in DBA mice. Indomethacin, which has been shown to prevent the development of PCT in BALB/c mice, prevented the infiltration of CD4+ T cells. In addition, pristane-induced levels of interferon-gamma greater than controls were found in the peritoneal lavages of BALB/c mice at all time points tested but not in DBA or indomethacin-treated BALB/c mice. In contrast, pristane injection increased levels of interleukin-5 in DBA but not BALB/c mice.

Animals↗
PubMed1993

In vitro immunotoxicity of +/- 2'-deoxy-3'-thiacytidine, a new anti-HIV agent.

The present study compares the in vitro effect of (+/-)-2'-deoxy-3'-thiacytidine (BCH 189) a new synthetic anti-HIV-1 dideoxynucleoside, with 3'-azido-3'-deoxythymidine (AZT) on the immune function of lymphocytes from 10 normal and 12 HIV-1+ patients (CDC II and III). The effect of different doses of BCH 189 and AZT was analysed in vitro on: (i) T cell proliferation after stimulation with concanavalin A (Con A) or anti-CD3 MoAb; (ii) B cell proliferation and immunoglobulin production after stimulation with pokeweed mitogen (PWM); (iii) cytokine production (IL-2, IL-6, GM-CSF, tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) from lymphocytes stimulated with anti-CD3 MoAb or phytohaemagglutinin (PHA). BCH 189 inhibited the proliferation of B and T lymphocytes from normal and HIV+ subjects less than AZT; even if lymphocytes from HIV+ (CDC III) subjects produced higher levels of IL-6 and TNF-alpha, neither BCH 189 nor AZT molecule interfered with cytokine release. Immunoglobulin production from B lymphocytes was inhibited only by a high concentration (50 microM) of BCH 189 or AZT. These results show that BCH 189 affects lymphocyte proliferation in vitro less than AZT, and support its use in clinical trials in HIV-infected patients.

Antiviral Agents↗
PubMed1992

Cellular response and anti-HBs synthesis in vitro after vaccination with yeast-derived recombinant hepatitis vaccine.

Two groups of subjects receiving two different doses of yeast-derived recombinant hepatitis B surface antigen (rHBsAg) (10 micrograms Gen-HB-Vax, Merck Sharp and Dohme and 20 micrograms Engerix-B, Smith Kline and French) were investigated for in vitro specific humoral and cellular response to the native protein. In vitro proliferative response was dependent on the following critical variables: (1) antigen-specific precursor lymphocytes were present in the peripheral blood for a very short time; (2) the number of circulating specific precursors was dependent on the dose of HBsAg used for vaccination; (3) the presence of antigen-presenting cells was necessary to obtain a blastogenic response in vitro. In vitro proliferation was enhanced by the addition of recombinant interleukin 2 (rIL-2). Spontaneous and stimulated (anti-CD3, pokeweed mitogen) anti-HBs antibody production in vitro was obtained in only eight out of 20 subjects after the fourth boost. Although a different immunogenicity of the two vaccines cannot be excluded, these data strongly suggest that T and B cells responsive to HBsAg present different kinetics of recirculation in the peripheral blood, depending on the antigen dose used for immunization.

Adult↗
PubMed1990

Age-associated changes in CD8+ and CD16+ cell reactivity: clonal analysis.

A cloning technique was used to estimate the frequency of proliferating T cell precursors, the growth capacity of clone-forming cells and the functional activity of clones established in vitro from peripheral blood lymphocytes of young and old people. The mean frequency of proliferating precursors was lower in the elderly as was the proliferative capacity of CD8+ clones. In contrast, CD4+ and CD16+ clones showed a proliferation similar to that obtained from young subjects. When the clones were examined for their functional activity, CD4+ clones from both groups failed to show any cytolytic activity, while CD8+ clones exerted cytolysis against K562 and in antibody-dependent cell-mediated cytotoxicity but this function was reduced in clones derived from old subjects. Similarly, CD16+ clones from the elderly showed a decreased activity at some effector-to-target cell ratios. We conclude that the impaired functional activity (T or NK-dependent) found in the peripheral blood of aged subjects persists after in vitro selection when these cells are analysed at clonal level.

Adult↗
PubMedDate not supplied

Phenotypic characterization of immunomagnetically purified umbilical cord blood CD34+ cells.

This study describes the multilineage differentiation pattern of purified CD34+ stem cells obtained from human umbilical cord blood. CD34+ cells were collected from 49 umbilical cord blood samples. Following immunomagnetic purification, cells were double stained with anti CD34 and CD71, CD61, CD7, CD19, CD33, CD36 and triple stained with anti CD34, CD38 and HLA-DR. Analysis were performed using a FACScan flow cytometer. After purification, the mean CD34+ cells' purity was 85.49 +/- 7.08%. Several subpopulations of umbilical cord blood CD34+ cells were identified indicating different lineage commitment. The majority of CD34+ cells expressed both CD38 and HLA-DR (91.74 +/- 3.76%), while those lacking CD38 were 3.43 +/- 2.12% (CD38-DR+) and 1.81 +/- 1.54% (CD38-DR-). These data were compared to the expression of lineage commitment markers on purified CD34+ cells from 5 mobilized peripheral blood samples. The percentage of peripheral blood CD34+CD38-DR+) and CD34+CD38-DR- cells was significantly lower than umbilical cord blood, 0.24 +/- 0.18% and 0.04 +/- 0.03% respectively. The knowledge and standardized of umbilical cord blood CD34+ cells phenotype is critical since umbilical cord blood volume is limited. The homogeneity of CD34+ subpopulation phenotype suggests that monitoring of lineage differentiation antigens may not be relevant for clinical use of umbilical cord blood samples. However, the observed higher percentage of pluripotent CD34+38- stem cells in umbilical cord blood compared to peripheral blood, that might explain the successful clinical use of umbilical cord blood even when low number of cells are used, candidates these antigens as the predictive parameter for clinical use of umbilical cord blood samples.

Antigens, CD↗
PubMedDate not supplied

A novel protocol that allows short-term stem cell expansion of both committed and pluripotent hematopoietic progenitor cells suitable for clinical use.

To obtain long-term engraftment and hematopoiesis in myeloablated patients, the cell population used for hematopoietic reconstitution should include a sufficient number of early pluripotent hematopoietic stem cells (HSCs), along with committed cells from the various lineages. For this purpose, the small subset of CD34+ cells purified from different sources must be expanded ex vivo. Since cytokines may induce both proliferation and differentiation, expansion would provide a cell population comprising committed as well as uncommitted cells. Optimization of HSC expansion methods could be obtained by a combination of cytokines able to sustain renewal of pluripotent cells yet endowed with poor differentiation potential. We used variations of the combinations of cytokines described by Brugger et al. [W. Brugger, S. Heimfels, R. J. Berenson, R. Mertelsmann, and L. Kanz (1995) N. Engl. J. Med. 333, 283-287] and Piacibello et al. [W. Piacibello, F. Sanavio, L. Garetto, A. Severino, D. Bergandi, J. Ferrario, F. Fagioli, M. Berger, and M. Aglietta (1997) Blood 89, 2644-2653] to expand UCB CD34+ cells and monitored proliferation rate and phenotype after 14 days of culture. Several hematopoietic lineage-associated surface antigens were evaluated. Our data show that flt3L and thrombopoietin in combination with IL-3, while sustaining a high CD34+ proliferation rate, provide a relatively low enrichment in very early uncommitted CD34+/CD38- cells. Conversely, in the absence of IL-3, they are less effective in inducing proliferation yet significantly increase the number of CD34+/CD38- cells. A combination of the above protocols, applied simultaneously to aliquots of the same sample, would allow expansion of both committed and pluripotent HSC. This strategy may represent a significant improvement for clinical applications.

ADP-ribosyl Cyclase↗
PubMedDate not supplied

Effect of stromal cells from human lymph nodes on the growth of osteosarcoma cell lines.

We investigated whether stromal cells obtained from human tonsils could interact and modulate the proliferation of the osteosarcoma cell in order to determine why lymph node metastases usually have a low incidence and remain occult using routine examinations. The effects of the supernatant of resting or activated stromal cells were analysed on osteoblastic cell proliferation of three different cell lines (HOS, U2, OS, MG-63). Only the proliferation of MG-63 was significantly inhibited. The direct adhesion of stromal cells to the osteosarcoma cell lines caused a greater inhibition of the proliferation of all three lines tested.

Cell Communication↗