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Biomedical subjects

A Santoni

Publications and source records attributed to A Santoni.

At least 127 records · Page 7Linked to original sources
PubMed1991

Inhibition of NK cell generation by Corynebacterium parvum.

Treatment of mice with Corynebacterium parvum (Cp) resulted in a substantial decrease of splenic NK activity associated with a reduced number of LGL. Cp also inhibited in vitro augmentation of NK cytotoxicity by IFN or IL-2 as well as generation of LAK activity. Localization experiments by using radiolabelled LGL indicated that the lower number of LGL in the spleen was not attributable to a Cp-induced alteration of LGL homing. Finally Cp was found to affect the ability of bone marrow cells to reconstitute NK activity in lethally irradiated mice, indicating that it can interfere with development of NK cells from bone marrow progenitors.

Animals↗
PubMed1990

T-cell restricted and unrestricted expression of transfected human interleukin-2 gene: phorbol ester- and calcium-inducible versus constitutive expression.

Interleukin-2 (IL-2) gene expression is tightly controlled and generally limited to antigenic stimulation of T cells. To study the cell-specific expression of the IL-2 gene, we transfected the intact human IL-2 gene, including 2.0 kb of 5' and 0.3 kb of 3' flanking sequences, into mouse NIH-3T3 fibroblasts and BFS lymphoma T cells and into human epithelial HeLa cells. Stable transformants (NIH-3T3,HeLa and BFS cells) carried an intact transfected IL-2 gene and constitutively expressed cytoplasmic human IL-2 mRNA which was not detected in vector-transfected cells. Constitutive expression of IL-2 mRNA in human IL-2 gene-transfected NIH-3T3 and HeLa cells was associated to the secretion of bioactive IL-2 protein, while no IL-2 production was observed in untransfected or vector-transfected cells. Cytoplasmic IL-2 mRNA observed in transfectants was larger (1.4 kb) than endogenous IL-2 mRNA of human T cells, although smaller than RNA containing unspliced intact introns. No alternative promoters or polyadenylation signals were used by these cells, but some intronic sequences were present in the 1.4 kb mRNA. Phorbol ester and calcium ionophore did not modulate the expression of the transfected IL-2 gene in NIH-3T3 and HeLa cells, while these agents increased its expression in transfected BFS lymphoma T cells. We conclude that when transfected into lymphoid and non-lymphoid cells the intact human IL-2 gene is constitutively expressed, while its phorbol ester/calcium-mediated inducible expression is restricted to T cells. This suggests that the constitutive and inducible expression of the IL-2 gene can be dissociated and are presumably subjected to separate regulatory pathways.

Animals↗
PubMed1990

CD69 is expressed on platelets and mediates platelet activation and aggregation.

CD69, a surface dimer so far considered an early activation antigen restricted to lymphocytes, was found constitutively expressed on human platelets. Biochemical analysis revealed that platelet CD69 appears on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a broad 55-65-kD band, in which three 55-, 60-, and 65-kD components were detectable when nonreduced, and as two 28- and 32-kD bands when reduced, corresponding to the two disulfide-linked chains of the dimer. It therefore closely resembles lymphoid CD69, although the resolution of the three bands under nonreducing conditions is not usually seen in lymphoid cells. Moreover, as CD69 expressed on activated lymphocytes and CD3bright thymocytes, both chains are constitutively phosphorylated. CD69 stimulation by anti-Leu-23 monoclonal antibodies induced platelet aggregation in a dose-dependent fashion. This effect was associated with Ca2+ influx and platelet degranulation, as revealed by adenosine triphosphate release. In addition, CD69 stimulation in platelets induced production of thromboxane B2 and PGE2, suggesting activation of arachidonic acid metabolism by cycloxygenase. As observed for CD69-mediated T cell activation, platelet activation through CD69 requires molecular crosslinking. These results suggest that CD69 may function as an activating molecule on platelets, as on lymphocytes, and point toward a more general role of this surface dimer in signal transduction.

Adenosine Triphosphate↗
PubMed1990

Interleukin-2 suppresses established long-term potentiation and inhibits its induction in the rat hippocampus.

The effects of recombinant interleukin-2 (rIL-2) on the potentiation of the synaptic transmission were studied in rat hippocampal slices by using extracellular field potential recordings. The application of rIL-2 inhibited the induction of both short-term (STP) and long-term potentiation (LTP) in a dose-dependent manner. In addition, rIL-2 (1000 U/ml) reduced both post-tetanic potentiation (PTP) and LTP maintenance phase. The possible involvement of rIL-2 action on the synaptic potentiation with the enzymatic activity of protein kinase systems is discussed.

Animals↗
PubMed1990

Transcriptional regulation of the interleukin 2 gene by glucocorticoid hormones. Role of steroid receptor and antigen-responsive 5'-flanking sequences.

Dexamethasone treatment of the Jurkat T77 cell clone inhibited the enhancing effect of 12-O-tetradecanoylporbol-13-acetate (TPA) and the calcium ionophore A23187 on the interleukin 2 (IL2) mRNA levels and gene transcription from intact nuclei. Dexamethasone treatment of Jurkat T77 cells inhibited the TPA/A23187-dependent activation of the transcription from the transfected pIL2CAT, containing 600 base pairs of the genomic sequences upstream of the coding region of IL2 gene, including the TPA/calcium responsive cis-regulatory elements and promoter sequences, driving the expression of the chloramphenicol acetyltransferase (CAT) gene. Transfection of either Jurkat T77 cell clone or glucocorticoid-resistant Jurkat cells with a human glucocorticoid receptor cDNA under the transcriptional control of the Rous sarcoma virus long terminal repeat (LTR) (pRShGR alpha) significantly increased or induced, respectively, the dexamethasone-mediated inhibition of the TPA/A23187-dependent expression of pIL2-CAT as well as the enhancing effect on the expression of the cotransfected CAT gene under the control of the mouse mammary tumor virus LTR, as a marker of glucocorticoid receptor action. This suggests a role for the glucocorticoid receptor in mediating the dexamethasone action on IL2 gene expression. To study the cis-regulatory sequence specificity of the dexamethasone-induced interference with the TPA/A23187-mediated T cell activating signals, we studied the effect of the hormone on the regulatory elements contained in the Rous sarcoma virus and human T lymphotropic virus 1 long terminal repeats and the SV40 promoter, which are known to be transcriptionally enhanced by those activating agents. Dexamethasone was unable to interfere with the TPA/A23187-mediated enhancement of these cis-regulatory elements, suggesting that the hormone effect is specific for IL-2 gene sequences. Our data suggest that the dexamethasone-mediated transcriptional inhibition of the IL2 gene is mediated by an interference with the protein kinase C and calcium-mediated trans-activation of the antigen-responsive and T cell-specific elements lying in the 5'-flanking region of the gene.

Animals↗
PubMed1990

Murine monoclonal antibody recognizing a 90-kDa cell-surface determinant selectively lost by multi-drug-resistant variants of CEM cells.

We describe a murine IgG1 monoclonal antibody (MAb56), specific for a cell-surface protein structure (MC56 determinant) expressed by the human CEM cell line. A large band of approximately 90 kDa was identified as the main specific component of the MC56 determinant. Such a 90-kDa protein is significantly associated with the drug-sensitive phenotype, its expression being progressively reduced quantitatively in multi-drug-resistant (MDR) variants of CEM cells, according to the extent of drug resistance. In addition, the MC56 determinant is expressed de novo in drug-sensitive revertant cell lines derived from MDR cells and unreactive with the MAb56. The MAb56 shows a high affinity towards the immunizing drug-sensitive CEM cell line (Ka = 1.86 x 10(9) L/mole) while not binding to MDR cell variants. The expression of the MC56 molecule on a variety of human cells and tissues makes such a cellular determinant a candidate as a marker for studying the MDR phenomenon both in vivo and in vitro.

Animals↗
PubMed1990

Natural killer activity and antibody-dependent cellular cytotoxicity in progressive systemic sclerosis.

Enhanced natural killer (NK) activity and normal lymphocyte antibody-dependent cellular cytotoxicity (ADCC) were observed in 16 patients with a diagnosis of progressive systemic sclerosis (PSS). Higher NK activity levels were observed against NK-sensitive K562 target cells, while the NK-resistant P815, Daudi and Raji cell lines were not lysed. Cytofluorimetric studies and morphological analysis of peripheral blood lymphocytes (PBL) showed an increased number of CD16 positive cells and large granular lymphocytes (LGL), indicating that the enhancement observed was probably attributable to an increase in the number of circulating NK cells.

Adult↗
PubMed1990

Soluble interleukin-2 receptor, interleukin-2 and interleukin-4 in sera and supernatants from patients with progressive systemic sclerosis.

We studied the sera of patients with progressive systemic sclerosis (PSS) for elevated levels of soluble interleukin-2 receptor (sIL-2R), interleukin-2 (IL-2) and interleukin-4 (IL-4). We also measured IL-2, IL-4 and B cell growth factor (BCGF) activity in supernatants of peripheral blood mononuclear cells from the same patients. The finding of elevated serum sIL-2R and IL-2, and the increased levels of IL-2, IL-4 and BCGF activity in culture supernatants indicates that T lymphocyte hyperactivity likely play a major role in PSS. The failure to detect under our experimental conditions a direct proliferative effect of recombinant IL-2 on enriched normal B cells might suggest that IL-4 is the cytokine mainly responsible of the BCGF activity recovered in PSS supernatants.

Adult↗
PubMed1990

Macrophages and interdigitating reticulum cells in normal human thymus and thymomas: immunoreactivity for interleukin-1 alpha, interleukin-1 beta and tumour necrosis factor alpha.

Pairs of monoclonal/polyclonal antibodies directed against interleukin-1 (IL-1) alpha, IL-1 beta and tumour necrosis factor (TNF) alpha were used for immunocytochemical identification of cytokine-containing cells in cryostat sections of human fetal thymuses and thymomas. In the fetal thymus immunoreactivity for IL-1 alpha was mainly confined to the medulla and was detected in S-100 positive interdigitating reticulum cells. The pattern of immunoreactivity for IL-1 beta was similar to that for IL-1 alpha, but the number of positive cells was much lower. Cells positive for TNF alpha were extremely rare in the fetal thymus. In 11 thymomas macrophages were constantly present and were regularly distributed throughout the tumour, whereas S-100 positive interdigitating reticulum cells were fewer and were characterized by a zonal distribution. Thymoma-associated macrophages were negative for IL-1 beta and were poorly reactive for IL-1 alpha, only a few positive cells being detected in five of the cases. Some macrophages with immunoreactivity for TNF alpha were detected in seven cases; they formed rosettes with surrounding lymphocytes or were located in a perivascular position. A marked immunoreactivity for TNF alpha was constantly detected in mast cell granules, which were observed in nine thymomas but not in fetal thymus. Positive immunoreactivity of interdigitating reticulum cells for IL-1 alpha was confirmed in five reactive lymph nodes and was also observed in Langerhans' cells in dermatopathic lymphadenitis. Our findings suggest that IL-1 alpha is a crucial molecule for interdigitating reticulum cell and Langerhans' cell function.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Characterization of Corynebacterium parvum-induced suppressor cells of mouse NK and ADCC activity.

Treatment of mice with Corynebacterium parvum (Cp) resulted in a substantial decrease in natural killer activity in the spleen at 10 days. The decrease in cytotoxicity was associated with the presence of splenic nonadherent (NA) suppressor cells, capable of inhibiting natural as well as antibody-dependent cellular cytotoxicity (ADCC). The nonadherent suppressor cells appeared to be null cells, lacking detectable expression of Thy 1, L3T4 (CD4), Lyt 2 (CD8), or asialo-GM1 and could be physically separated from cells with NK activity by centrifugation on Percoll discontinuous density gradients. Our results indicate that Cp can negatively modulate cytolytic functions of NK cells by inhibiting the effector phase of cytotoxicity.

Animals↗
PubMed1990

Augmentation of mouse natural killer (NK) activity by GM-1/P, a processed form of monosialoganglioside GM-1.

We describe the immunomodulatory activity of GM-1/P a processed form of GM-1 (monosialoganglioside) extracted from ox brain, purified and physically modified. We examined the effect of in vivo and in vitro treatment of GM-1/P on natural (NK) activity and its ability to induce the production of interleukin-2 (IL-2) in the mouse. In vivo treatment with GM-1/P (1 mg/Kg, i.v., day-1) resulted in a marked increase and in a change of distribution of NK activity, which was associated with lower density Percoll fractions. Marked increase was already observed at 18 hrs and then declined by day 4. In vitro treatment with GM-1/P (2 micrograms/ml) enhanced NK activity of B6 spleen cells, already after 6 hours of incubation, remaining at plateau levels within 18 hours. A role of IL-2 in this enhancement was suggested by the ability of an anti-IL-2 rabbit antiserum to abolish in vitro increased cytotoxicity. The presence of IL-2 in the supernatants of splenocytes from GM-1/P (1mg/Kg, i.v., ,day-1) treated mice stimulated with Con A or Con A plus TPA for 48 hrs was evaluated by proliferation of an IL-2 dependent CTLL cell line. GM-1/P by itself was unable to stimulate IL-2 production; however it markedly increased IL-2 production induced by Con A or Con A plus TPA.

Adjuvants, Immunologic↗
PubMed1990

Cytokine production (IL-1 alpha, IL-1 beta, and TNF alpha) and endothelial cell activation (ELAM-1 and HLA-DR) in reactive lymphadenitis, Hodgkin's disease, and in non-Hodgkin's lymphomas. An immunocytochemical study.

Cryostat sections of 58 lymph nodes were immunostained with a polyclonal rabbit serum against IL-1 alpha, and with monoclonal antibodies directed to IL-1 alpha (Vmp18), IL-1 beta (Vhp20 and BRhC3), and tumor necrosis factor alpha (TNF alpha) (B154.7). Furthermore the presence of cytokine-containing cells was correlated with the expression of endothelial leukocyte adhesion molecule (ELAM-1; 29F2) and of human leukocyte antigen (HLA-DR) (OKIa-1) by endothelial cells. Cells containing IL-1 and/or TNF alpha were detected mainly in pathologic conditions characterized by reactive or neoplastic expansion of the lymph node paracortex. Cells positive for IL-1 were detected in 16 of 21 cases of Hodgkin's disease, in 4 of 4 cases of T-NHL, and in 5 cases of diffuse or mixed lymphadenitis. Interleukin-1 alpha was detected in macrophages, interdigitating reticulum cells (IDRCs), endothelial cells, and neoplastic Hodgkin's and Reed-Sternberg (H-RS) cells. Cells positive for IL-1 beta were much fewer and consisted mainly of macrophages. Hodgkin's Reed-Sternberg cells were negative for IL-1 beta even after in vitro stimulation with bacterial endotoxin. Tumor necrosis factor alpha (TNF alpha) was present in macrophages and H-RS cells. Endothelial leukocyte adhesion molecule-1 expression by endothelial venules was detected in 17 of 20 cases of Hodgkin's disease, in 2 of 4 cases of T-NHL, and in 5 of 5 cases of diffuse lymphadenitis. In these pathologic conditions, HLA-DR antigens also were expressed frequently by endothelial cells. Cytokine-containing cells and ELAM-1-positive high endothelial venules (HEV) were extremely rare in lymph nodes involved by follicular lymphadenitis (12 cases) or B-NHL (16 cases). In cases of reactive or neoplastic B-cell proliferations, HLA-DR-positive HEVs still were present often. Our results indicate that IL-1/TNF alpha production at tissue level is often associated with ELAM-1 expression by HEVs, but is less well correlated with expression of HLA-DR antigens by endothelial cells.

Adolescent↗
PubMed1990

Perilymphatic injections of cytokines: a new tool in active cancer immunotherapy. Experimental rationale and clinical findings.

Various strategies for local immunotherapy performed by using lymphokines and lymphocytes are presented. In experimental mice models, the antitumor reaction elicited through the injection of little amounts of IL-2 and gamma-IFN at the tumor growth site is significantly enhanced by the concurrence of lymphocytes from tumor bearing mice artificially admixed to challenging tumor cells. These lymphocytes act as initiator or helper cells that elicit both a local and a systemic long lasting immune reaction by the release of additional lymphokines. The reaction activated mostly involves draining lymph nodes, where multiple reaction mechanisms are induced. The local injection of cocktails of molecularly defined lymphokines can also mimic the helper action of lymphocytes and trigger a similarly effective anti-tumor reaction. A set of pilot clinical trials with IL-2 or gamma-IFN injected perilymphatically were initiated in patients with advanced primary or recurrent localized tumors of the head and neck and the bladder. This treatment appears to elicit a local reaction by activating a few pathways of patients immunoreactivity, whose efficiency may well be high, as shown by the tumor inhibition often observed.

Amino Acid Sequence↗
PubMed1989

In vitro migration of rat large granular lymphocytes.

Rat peripheral blood large granular lymphocytes (LGL) were isolated by fractionation on discontinuous Percoll gradients. LGL migration was studied using nitrocellulose filters. Rat LGLs migrated into nitrocellulose filters in response to N-formyl-methionyl-leucyl-phenylalanine (f-MLP), casein, and serum components. Percoll-enriched high-density lymphocytes had small, but significant, migratory capacity in response to stimuli under these conditions. Removal of OX-19+ contaminating cells by panning confirmed the migratory capability of rat LGL/NK cells under these conditions. Checkerboard analysis of the LGL response to chemoattractants revealed that induction of migration involved chemokinesis although a chemotactic component was also discernible. The prompt migration of rat LGL in response to different stimuli is consistent with the hypothesis that these cells may represent one of the first easily mobilizable lines of resistance against noxious agents. In the rat combined in vitro/in vivo studies may provide a better understanding of the regulation of LGL recruitment and extravasation.

Animals↗
PubMed1989

Rat natural killer cells synthesize fibronectin. Possible involvement in the cytotoxic function.

The ability of NK cells to synthesize and secrete fibronectin (FN), an extracellular matrix glycoprotein which plays a key role in many biologic processes including cellular adhesion, morphology, cytoskeletal organization, cell migration, and invasiveness, was studied. By using affinity-purified polyclonal antibodies directed against human cellular or plasma FN, the presence of FN was evidentiated on Percoll-purified rat large granular lymphocyte or on a large granular lymphocyte tumor cell line (CRC) by flow cytometry and immunoelectron microscopy. Its expression increased after NK cell activation by poly I:C administration. Biochemical analysis by immunoprecipitation and SDS-PAGE indicated that FN was associated to cell surface and secreted in the supernatant in a molecular form similar to that of FN from L929 fibroblasts. In an attempt to understand the role of FN in the NK cell function, we found that an antibody against human plasma FN and its F(ab')2 fragment inhibited NK cytotoxicity against YAC-1 target at the effector cell level. Inhibition occurred at the postbinding level, because F(ab')2 anti-FN inhibited induction of phosphatidylinositol hydrolysis by YAC-1 target cells, whereas binding to target cells was not affected. The possible role of FN in the NK cytotoxic function is suggested.

Animals↗
PubMed1989

Steroid sensitivity of thymocyte subpopulations during intrathymic differentiation. Effects of 17 beta-estradiol and dexamethasone on subsets expressing T cell antigen receptor or IL-2 receptor.

We have studied the effects of the steroid hormones, 17 beta-estradiol and dexamethasone, on the relative proportion of thymocyte expression of CD4 (L3T4), CD8 (Ly-2), TCR and IL-2R, used to identify different stages of thymocyte differentiation. After short-term in vivo steroid treatment, a significant decrease in the number and proportion of the CD4+/CD8+, double positive subpopulation was observed in parallel with a proportional increase in the percentage of the CD4+/CD8- single positive, of the CD4-/CD8-, double negative and, to a lesser extent, of the CD8+/CD4- subsets. Either steroid treatment increased the proportion of cells expressing either the epsilon-chain of the CD3 complex and/or the beta-chain of the TCR (beta-TCR) (TCR+/CD3+) and the 55 kDa protein of the IL-2R (IL-2R+), related to the increase of CD4+ SP thymocytes and of DN cells, respectively. Furthermore, the increased proportion of CD3+ cells could also be partially related to the increase of both the CD4+ and DN subsets. A decrease of the effect on either DN/IL-2R+ cells or CD4+ SP cells was selectively observed after long-term treatments with 17 beta-estradiol or DEX, respectively. It is concluded that after short-term administration, different steroid hormones mediate a similar selective depletion of DP, TCR-/CD3-, IL2R- cells presumably in an intermediate stage of differentiation. However, either steroid effects evolve differently in long-term treatment schedules, resulting in different effects on early (DN/IL2R+) and late (SP/IL2R-) steps of thymocyte differentiation.

Animals↗