Biomedical subjects

C Sorio

Publications and source records attributed to C Sorio.

23 records · Page 2Linked to original sources

PubMed1992

Generation of signals activating neutrophil functions by leukocyte integrins: LFA-1 and gp150/95, but not CR3, are able to stimulate the respiratory burst of human neutrophils.

To address the question whether leukocyte integrins are able to generate signals activating neutrophil functions, we investigated the capability of mAbs against the common beta chain (CD18), or the distinct alpha chains of CR3, LFA-1, or gp150/95, to activate neutrophil respiratory burst. These investigations were performed with mAbs bound to protein A immobilized to tissue culture polystyrene. Neutrophils plated in wells coated with the anti-CD18 mAbs IB4 and 60.3 released H2O2; H2O2 release did not occur when neutrophils were plated in wells coated with an irrelevant, isotype-matched mAb (OKDR), or with mAbs against other molecules (CD16, beta 2-microglobulin) expressed on the neutrophil surface at the same density of CD18. Four different mAbs, OKM1, OKM9, OKM10, 60.1, which recognize distinct epitopes of CR3 were unable to trigger H2O2 or O2- release from neutrophils. However, mAbs against LFA-1 or gp150/95 triggered both H2O2 and O2- release from neutrophils. Stimulation of neutrophils respiratory burst by both anti-CD18, and anti-LFA-1 or gp150/95 mAbs was totally inhibited by the microfilaments disrupting agent, cytochalasin B, and by a permeable cAMP analogue. While the capability to activate neutrophil respiratory burst was restricted to anti-LFA-1 and gp150/95 mAbs, we observed that mAbs against all members of leukocyte integrins, including CR3, were able to trigger neutrophil spreading. These findings indicate that, in neutrophils, all three leukocyte integrins can generate signals activating spreading, but only LFA-1 and gp150/95 can generate signals involved in activation of the respiratory burst. This observation can be relevant to understand the mechanisms responsible for the activation of neutrophil respiratory burst by tumor necrosis factor-alpha, which has been shown to be strictly dependent on expression of leukocyte integrins (Nathan, C., S. Srimal, C. Farber, E. Sanchez, L. Kabbash, A. Asch, J. Gailit, and S. Wright. 1989. J. Cell Biol. 109:13411349.

Antibodies, Monoclonal↗

PubMed1992

The CD4 molecule belongs to the phenotypic repertoire of most cases of acute myeloid leukemia.

In the present study fresh leukemic cells obtained from 23 patients with acute myeloid leukemia (AML; FAB subtypes: three M1, five M2, two M3, five M4, eight M5) were investigated for the membrane expression of the CD4 molecule by cytofluorimetric analysis with an anti-CD4 monoclonal antibody (mAb). In 15 cases the presence of the CD4 mRNA was also investigated using Northern blot analysis. Membrane expression of the CD4 molecule was demonstrated in 19 out of 23 cases, and it was found to be weaker than in CD4+ lymphocytes and monocytes obtained from normal controls. Full-length CD4 mRNA was detected in 12 out of 15 (80%) cases, and AML cells positive for CD4 mRNA expression also expressed the CD4 antigen. Since the CD4 molecule expressed by T cells is associated with p56lck, a member of the src family of intracellular tyrosine kinases, we investigated whether the CD4 molecule expressed by myeloid blasts is also associated with a tyrosine kinase activity. In vitro kinase assays performed on anti-CD4 immunoprecipitates from lysates of myeloid leukemia cells from four CD4+ cases were negative for the presence of a tyrosine kinase activity. This finding was not due to the lack of expression of members of the src family since we were able to detect at least p60src and p59fyn in myeloid leukemia cells. According to our results, the CD4 molecule seems to belong to the phenotypic repertoire of most AML, irrespective of their FAB subtypes. However, in myeloid blasts this molecule is not associated with a tyrosine kinase activity as it occurs in T lymphocytes.

Blotting, Northern↗

PubMed1992

Induction of differentiation of the human myeloid cell line, ML3, by tumour necrosis factor and interferon-gamma is accompanied by enhanced expression of the CD4 protein and messenger RNA.

Tumour necrosis factor (TNF) and interferon-gamma (IFN-gamma) induce differentiation of human myeloid cell lines along the monocytic lineage. In this study we investigated the effects of TNF and IFN-gamma on the expression of the CD4 protein and messenger RNA (mRNA) in the two myeloid cell lines, ML3 and HL-60. We observed that CD4 antigen expression on ML3 cells is almost undetectable and that TNF and IFN-gamma induced CD4 antigen expression on these cells. HL-60 cells express surface CD4 antigen at high density and treatment with TNF and IFN-gamma caused a decrease of CD4 expression. We also investigated the expression of CD4 mRNA in ML3 and HL-60 cells. ML3 constitutively express, albeit at low levels, CD4 mRNA. TNF induced CD4 mRNA in ML3 cells and IFN-gamma synergistically potentiated the effect of TNF, thus indicating that the enhanced expression of the CD4 protein on ML3 cells is due, at least in part, to an enhanced accumulation of the CD4 mRNA. CD4 mRNA is constitutively expressed in HL-60 cells at high levels. TNF and IFN-gamma, alone or in combination, did not cause any significant change of CD4 mRNA expression in HL-60 cells, thus indicating that decrease of surface CD4, which accompanies differentiation with these cytokines, is likely due to alterations of the CD4 protein synthesis and/or transport to the plasma membrane. These results provide evidence that myeloid cell lines are heterogeneous in expression of CD4, and that in ML3 cells, which constitutively express low levels of CD4 mRNA and undetectable amounts of surface CD4, the predominant effect of the two cytokines is to induce both CD4 mRNA and protein.

Blotting, Northern↗

PubMed1991

Activation of human monocyte-derived macrophages by interferon gamma is accompanied by increase of poly(ADP-ribose) polymerase activity.

We have investigated poly(ADP-ribosyl)ation processes in human monocyte-derived macrophages and the effect of the activating cytokine, interferon gamma (IFN-gamma) on these processes. IFN-gamma was shown to increase the activity of poly(ADP-ribose) polymerase in human macrophages. A 2-3-fold enhancement of poly(ADP-ribose) polymerase activity was observed after 3-4 h of incubation with IFN-gamma, whose effects were dose-dependent and maximal at 20-50 U/ml. Staining with anti-poly(ADP-ribose) antibodies and purification of ADP-ribosylated nuclear proteins by affinity chromatography over boronate agarose showed that enhancement of poly(ADP-ribose) polymerase activity by IFN-gamma was accompanied by accumulation of poly(ADP-ribose) polymers in nuclear proteins. The effects of IFN-gamma on poly(ADP-ribose) polymerase activity were not due to an enhanced accumulation of the message for the enzyme, indicating that the activation of the enzyme activity was due to post-transcriptional modifications. IFN-gamma was shown to induce DNA strand breaks in human macrophages. This phenomenon followed the same time-course and was evident with the same doses of IFN-gamma that increased poly(ADP-ribose) polymerase activity. Since poly(ADP-ribose) polymerase is known to require DNA nicks for its activity, the capability of IFN-gamma to induce DNA strand breaks can explain its effects on poly(ADP-ribosyl)ation processes.

DNA Damage↗

PubMed1991

Protein myristoylation in human mononclear phagocytes: modulation by interferon-gamma and tumor necrosis factor-alpha.

Labelling of cells with [3H]myristic acid and analysis of labelled proteins by SDS-PAGE and fluorography, enabled the identification of a limited number of myristoylated proteins in human monocytes and monocyte-derived macrophages. In human monocytes, cultivated for one to three days, major myristoylated proteins observed were of 18 kDa, 44 kDa, 60-62 kDa, 90 kDa, and a doublet of 38-40 kDa. Differentiation of monocytes to macrophages by in vitro cultivation was accompanied by a selective decrease in the 60-62 kDa protein. Cultivation of the cells in the presence of the macrophage-activating cytokines interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha), prevented the decrease in the expression of the 60-62 kDa myristoylated protein. The effect of cytokines was observed when monocytes were treated with IFN-gamma or TNF-alpha for 24 or 48 h and protein myristoylation analyzed at day four of culture. Maintenance of monocytes in culture for up to nine days in the presence of cytokines prevented the decrease in the expression of the 60-62 kDa myristoylated protein. IFN-gamma had additional effects on myristoylation of macrophage proteins. Treatment of monocytes with IFN-gamma for a few hours caused the induction of a 66 kDa protein. Induction of this myristoylated protein by IFN-gamma was time-dependent and peaked at six hours. Analysis of the subcellular distribution of the 66 kDa protein induced by IFN-gamma showed that, analogously to other myristoylated proteins, most of it was associated with cell membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Differentiation↗