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Biomedical subjects

A Santoni

Publications and source records attributed to A Santoni.

At least 145 records · Page 8Linked to original sources
PubMed1989

Effects of cadmium on lymphocyte activation.

The effects of cadmium (Cd) on phytohemoagglutinin or phorbol myristate acetate-induced lymphocyte activation were investigated and a dose-dependent inhibition of cell proliferation was found. Kinetic studies revealed that the Cd-sensitive step is an early event of T cell stimulation. Failure of IL2 secretion and reduction of IL2 receptor expression in the Cd-treated cells are also reported. Regardless of which mechanism is responsible for Cd effects, our studies show that the inhibition of lymphocyte activation is associated with reduced [3H]phorbol dibutyrate binding to Ca2+-phospholipid-dependent protein kinase and altered breakdown of phosphatidylinositols. Thus, Cd interferes with two biochemical events which play a critical role in lymphocyte signal transduction and activation.

Adult↗
PubMed1989

Granzyme A expression by normal rat natural killer (NK) cells in vivo and by interleukin 2-activated NK cells in vitro.

Granzyme A (TSP-1) is a serine esterase expressed in cytotoxic T and natural killer (NK) cell lines. Its presence in in vivo primed T cells is disputed at present. Here we show that normal rat NK cells contain granzyme A in vivo and that its expression is augmented by their short-term in vitro treatment with IL 2. Granzyme A expression in a NK cell population with LAK activity has also been examined.

Animals↗
PubMed1989

Surface molecules involved in CD3-negative NK cell function. A novel molecule which regulates the activation of a subset of human NK cells.

Natural killer cells are characterized by the lack of CD3/TCR molecules and by the expression of CD16 and CD56 (NKHI or Leu19) surface antigens. In addition to their ability to lyse certain tumor target cells, they release lymphokines including tumor necrosis factor and interferon gamma. Another unexpected functional capability of at least some NK cells is the ability to specifically recognize and lyse certain normal allogeneic cells (PHA-induced blasts). MAbs directed to CD2 or to CD16 surface molecules induced triggering of NK cells leading to target cell (p815) lysis in a redirected killing assay. Importantly, different from induction of T cell activation, single anti-CD2 MAbs were sufficient to trigger NK cell function. Another MAb (GL183) inducing NK cell triggering recognized a novel surface molecules expressed on 20-50% of resting or cultured NK cells. Cloned GL183+ cells displayed a variable degree of cytolytic activity against a number of human target cells of different histotype; moreover, this activity was strongly enhanced by the addition of GL183 MAb. On the other hand, GL183 MAb inhibited lysis of murine lines (including P815). Thus on P815 target cells GL183 MAb has an effect antithetical to that of other stimuli including PHA, anti-CD2 or anti-CD16 MAbs. GL183 MAb, added simultaneously to one or another of the stimuli above, strongly inhibited the target cell lysis induced by these stimuli. Thus, GL183 may represent an important molecule in the process of activation/regulation of phenotypically-defined NK cell subsets.

Antibodies, Monoclonal↗
PubMed1989

Regulation of muscle acetylcholine receptor-channel function by interferon.

The effect of the antiviral agent interferon (IFN) on the function of the nicotinic acetylcholine receptor (AChR) channel, has been investigated in both mammalian cultured myotubes and adult fibres, using the single channel recording patch-clamp technique. Shortened AChR-channel lifetime, and occasionally reduced channel conductance and slowed opening frequency were seen with fibroblast IFN (IFN-beta) in the mouse myotubes, and with IFN-beta and leucocytes IFN (IFN-alpha), in the rat muscle fibres. These effects paralleled an increase in the cytosolic level of cAMP. This suggests that IFN exerts a regulatory action on AChR function. A similar regulatory action on other receptor may be responsible for some of the neurological side effects observed in patients treated with IFN.

Animals↗
PubMed1989

Effects of protein kinase C (PK-C) activators and inhibitors on human large granular lymphocytes (LGL): role of PK-C on natural killer (NK) activity.

The role of protein kinase C (PK-C) in the early metabolic events involved in human natural killer (NK) cell activation has been studied through the action of PK-C-specific activators and inhibitors. Highly purified human large granular lymphocytes (LGL) were treated for 1 hr with the diacylglycerol analog 1-oleoyl-2-acetyl glycerol (OAG) (10(-4)-10(-5) g/ml) or with 12-O-tetradecanoylphorbol-13-acetate (TPA) (10(-8)-10(-10) g/ml), both specific activators of PK-C. Both these agents consistently increased NK activity against K562 target cells. Suboptimal doses of either OAG or TPA also synergized with Ca2+ ionophores to augment spontaneous cytotoxic activity. Pretreatment of LGL with 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrocloride (H7) (5-40 microM), a potent PK-C inhibitor, greatly reduced NK activity in a time- and dose-dependent fashion. By contrast, N-(2-guanidinoethyl)-5-isoquinolinesulfonamide hydrochloride (HA 1004), a potent cAMP- and cGMP-dependent PK inhibitor with almost no effect on PK-C, marginally reduced NK activity. Moreover, almost complete NK activity inhibition was observed when H7 (10 microM), but not HA 1004 (50 microM), was present in the NK assay. Finally, 48 hr stimulation of LGL with TPA (10(-6) g/ml), a treatment able to inactivate most of the PK-C cellular pool, almost completely abrogated NK activity. This functional evidence was supported by phosphorylation of several endogenous substrates which occurs within 5 min in TPA-treated LGL. Two proteins of 70 and 56 kDa have been identified as major PK-C substrates, together with other phosphorylated proteins with MW ranging from 177 to 43 kDa. H7, but not HA 1004, almost completely inhibited the TPA-induced phosphorylation of all of these proteins in the NK cells. These data strongly suggest that selective activation of PK-C plays an essential role in the mechanisms of NK cell activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1989

Laminin synthesis by NK cells and modulation of its expression by TPA (12-O-tetradecanoylphorbol-13-acetate).

Natural killer (NK) cells have been suggested to play a major role in resistance against metastatic spread of tumors. This study was aimed at understanding whether laminin (LM), a component of the extracellular matrix involved in the mechanism of tumor invasion and cell interaction, is expressed by NK cells. The results indicate that NK cells can synthesize and display on the cell surface LM and that TPA can modulate its expression. Our findings suggest that the presence of LM on NK cells could be relevant in the control of tumor invasion by NK cells.

Animals↗
PubMed1989

Reduced natural killer cell activity in major depression: neuroendocrine implications.

Natural killer cell activity (NKCA) was significantly reduced in a group of depressed patients, melancholic subtype, compared to sex- and age-matched controls. Corticotropin and cortisol values were significantly higher in the depressed subjects than in the controls, but no correlation between high hormone levels and low immunological activity was found in the patients.

Adrenocorticotropic Hormone↗
PubMed1989

Overnight incubation of mouse spleen cells in recombinant IL-2 generates cytotoxic cells with NK characteristics from precursors enriched with or devoid of LGL.

Interleukin-2 (IL-2) augments natural killer (NK) activity as well as generating effector cells named lymphokine activated killer cells (LAK) which are capable of lysing a wide spectrum of target cells. A large body of evidence has been accumulated to evaluate the relationship between NK and LAK cells and conflicting results have been reported. Our study was addressed to further analyse this relationship and in particular to investigate whether in a short incubation IL-2 is merely capable of augmenting the activity of pre-existing killer cells, or whether it can also promote the differentiation of precursor cells. Eighteen-hour culture of mouse spleen cells in human recombinant IL-2 induced a DNA-synthesis-independent generation of cytotoxic cells bearing an NK phenotype (aGM-1+, Thy1.2+/-, CD8-, CD4-). These were generated from precursor cells also bearing an NK phenotype, recovered either from low density Percoll fractions enriched in lytic cells with LGL morphology as well as from high density fractions devoid of LGL and cytotoxic activity.

Animals↗
PubMed1989

Polyclonal B lymphocyte activation in progressive systemic sclerosis.

In 13 women affected by progressive systemic sclerosis (PSS) the activation state of circulating B lymphocytes by use of monoclonal antibodies and the in vitro IgG, IgA, IgM synthesis by peripheral blood mononuclear cells (PBMC) cultured with or without pokeweed-mitogen (PWM) were evaluated. The total and "activated" B lymphocytes were increased. The supernatants of PBMC cultured without PWM contained increased IgG and IgA levels; only in two patients, however, were IgM levels increased. The addition of PWM augmented IgG and IgA levels only in three cases and never IgM levels. Our results indicate that the polyclonal hyperactivity of B lymphocytes is a major immunologic feature in PSS patients. The lack of increase of in vitro immunoglobulin synthesis in the presence of PWM suggests either that B lymphocytes, already maximally activated in vivo, are unresponsive to further mitogen stimulation or that a more complex imbalance of B lymphocyte responsiveness to PWM may exist.

Adult↗
PubMed1989

Immunoreactivity for IL-1 beta and TNF alpha in human lymphoid and nonlymphoid tissues.

Monoclonal antibodies (MAbs) against two non-cross-reacting antigens of human IL-1 beta (Vhp20 and BRhC3) and human TNF alpha (B154.2 and B154.7) were applied to identify cytokine-containing cells in tissue sections and in cell suspensions. IL-1 beta- or TNF alpha-positive cells were not present in immunostained cytocentrifuge smears prepared from freshly isolated peripheral blood leukocytes, spleen, and lymph node cells. After 18 hours of culture with bacterial endotoxin (LPS), 80% to 90% of blood monocytes, 30% of spleen macrophages, and 2% to 28% of lymph node macrophages were strongly positive for IL-1 beta with either of the MAbs. Furthermore, 25% to 35% of blood monocytes and 6% to 60% of lymph node macrophages were stained for TNF alpha. Cells positive for IL-1 beta or TNF alpha were extremely rare in sections of normal thymus, spleen, and lymph nodes. Immunoreactivity for IL-1 beta or TNF alpha was frequently observed in sections of granulomatous lymphadenitis (N = 11). IL-1 beta or TNF alpha staining was confined to the epithelioid macrophages forming the granuloma, and the intensity of TNF alpha reactivity was generally stronger. The high frequency of cytokine-containing cells in this pathologic condition was confirmed in a cell suspension study showing that 20% of epithelioid macrophages were weakly positive for IL-1 beta and 80% were strongly positive for TNF alpha. The presence of cytokine-containing cells was investigated in cryostat sections of several nonlymphoid organs with normal histologic appearance. IL-1 beta reactivity was not observed in any of the tissues. TNF alpha reactivity was frequently demonstrated in isolated macrophages embedded in the interstitial connective tissue.

Humans↗
PubMed1988

Obligatory role of IFN-gamma in induction of lymphokine-activated and T lymphocyte killer activity, but not in boosting of natural cytotoxicity.

The biological role of the murine IFN-gamma endogenously secreted during cell activation has been probed by the use of a rat mAb (AN18) that specifically neutralizes its activity. When An18 mAb is added to the cultures of BALB/c and C57BL/6 nylon nonadherent spleen cells (naSpc) stimulated for 18 h with 1000 U of IL-2, the normally released IFN-gamma can no longer be detected in the supernatants and the IL-2-induced proliferative response is markedly reduced as compared with control cultures set up in the presence of an unrelated rat mAb. By contrast, the increased natural cytotoxicity is not affected. The 96-h culture of both BALB/c and C57BL/6 naSpc in the presence of 1000 U of IL-2 resulted in marked lymphocyte proliferation and generation of lymphokine-activated killer activity. The presence of An18 mAb strongly inhibited both functions. Similarly, when naSpc were stimulated with mitomycin C-inactivated allogeneic leukocytes in the presence of An18 mAb, the normal proliferative response and specific cytotoxicity were almost abolished, whereas the secretion of IL-2 was in no way affected. Lymphocytes recovered from 3-day cultures stimulated by IL-2 or allogeneic cells in the presence of An18 mAb displayed a decrease of the expression of the p55 chain of IL-2R, as shown by flow cytofluorimetry. Moreover, binding experiments with 125I-labeled IL-2 showed that lymphocytes from allostimulated cultures set up in the presence of An18 mAb display a decreased number of low affinity and almost no high affinity IL-2R as compared with control cultures. These data show that endogenous IFN-gamma plays an obligatory role for the de novo induction of cytolytic activity in lymphokine-activated killer cells and CTL, most probably by affecting the membrane expression of high affinity IL-2R.

Animals↗
PubMed1988

Proliferative effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) and calcium ionophores on human large granular lymphocytes (LGL).

The proliferative responses of natural killer (NK) cells to 12-O-tetradecanoylphorbol-13-acetate (TPA), which directly activates protein kinase c(PKC), and to the Ca2+ ionophores A23817 and ionomycin, known to enhance the intracellular calcium, have been investigated. Highly purified large granular lymphocytes (LGL) were cultured for 12-30 hr in the presence of TPA, ionomycin, or A23817. TPA alone (1-20 ng/ml) triggered rapid LGL proliferation, whereas the calcium ionophores were ineffective. The addition of either calcium ionophore to suboptimal doses or TPA (0.1-0.5 ng/ml) resulted in a synergistic effect on LGL proliferation. Under these conditions high levels of IL-2 activity were released by the LGL. Phenotypic analysis revealed the rapid loss of the Fc gamma receptors (CD16) on LGL and the induction of the expression of IL-2 (CD25) and transferrin receptors and of HLA-DR, but not of CD3. Removal of extracellular Ca2+ by addition of EGTA at the beginning of the culture greatly depressed LGL proliferation and IL-2 production, and blocked phenotypic changes, such as the expression of Tac antigen. Finally, progression to the proliferative phase of LGL, activated by TPA alone or with ionomycin, was completely abrogated by a hyperimmune anti-IL-2 antiserum.

Antigens, Surface↗
PubMed1987

Interleukin 2 activated tumor inhibition in vivo depends on the systemic involvement of host immunoreactivity.

Daily local administration at the tumor challenge site of 10 injections of 10 U of recombinant interleukin 2 (IL 2) obtained from different factories induces a consistent, though limited inhibition of the growth of CE-2, a poorly immunogenic methylcholanthrene-induced tumor. By contrast, almost complete tumor inhibition is observed when these injections are performed in mice challenged with tumor cells admixed at 1:5 cell ration with nylon wool column purified lymphocytes obtained from tumor-bearing animals. The host immune system plays a fundamental role in this lymphokine-activated tumor inhibition (LATI), which is derived from the local combination of IL 2 and nonreactive lymphocytes. When the host is sublethally irradiated, or the reactivity of L3T4 and Asialo GM1 lymphocytes is suppressed by in vivo antibody treatment, in fact, LATI no longer takes place. Daily injections of antibody to murine interferon-gamma or cyclosporin A have the same effect, indicating that lymphokine release plays an important role in the recruitment of host reactivity. The morphological data show that when LATI is taking place the tumor challenge area becomes infiltrated by mononuclear cells and granulocytes (mostly eosinophils), which establish close contacts with each other and with tumor cells as determined at ultrastructural analysis. Tumor draining lymph nodes display marked expansion of cortical and paracortical areas. Lymphocyte proliferation, interferon-gamma release and cytotoxicity against CE-2 and YAC-1 target cells are greatly enhanced during LATI. Contralateral lymph nodes and the spleen also show a slight increment of these functions. In mice challenged with CE-2 tumor cells only and receiving daily IL 2 injections, these reaction functions (with the exception of interferon-gamma secretion) are also enhanced, though to a lesser extent than during LATI and only in tumor-draining lymph nodes. Last, the growth of a second contralateral tumor challenge is significantly impaired during or after LATI, showing that a persistent and effective systemic reactivity can be quickly induced in this way.

Animals↗
PubMed1987

Estrogen and antiestrogen modulation of the levels of mouse natural killer activity and large granular lymphocytes.

We investigated the time course of the 17 beta-estradiol effect on mouse natural killer (NK) activity and the number of splenic large granular lymphocytes (LGL), a cell population recently associated with natural cytotoxicity and enriched in low density fractions of Percoll discontinuous density gradients. After 7 days of in vivo treatment with estrogen, an increased cytotoxicity against YAC-1 lymphoma cells was observed using only as effectors cells recovered from higher density fractions, usually devoid of NK activity. In contrast, after a 30-day treatment, augmented NK activity and an increase in LGL number were observed in the lower density Percoll fractions. Similar results were observed after a 30-day treatment with the antiestrogen tamoxifen. The cytotoxicity of both low density and high density splenocyte fractions was totally abrogated by treatment with antiserum to asialo GM1 plus complement, whereas anti-Thy 1.2 antibody treatment only partially decreased the reactivity. Further estrogen administration up to 60 days decreased both NK activity and LGL number. It is concluded that estradiol can induce opposite effects on NK activity depending on the time of treatment, with stimulation of NK activity during the first 30 days after treatment followed by depressed NK activity 1 month later.

Animals↗
PubMed1987

Hypothalamic control of certain aspects of natural immunity in the mouse.

Electrothermocoagulation (ETC) of the individual nuclei of the median region of the hypothalamus (MH) in the C57BL/6 mouse leads to a significant reduction in the cytotoxic activity of natural killer cells (NK) and the number of large granular lymphocytes (LGL) compared with intact or sham-operated controls. This effect, however, is less than that observed after simultaneous destruction of all MH nuclei. By contrast, no significant change in NK activity was noted after ETC of the anterior (AH) or posterior (PH) regions. Diminution of NK activity due to nuclear MH destruction is not an outcome of the change in adenohypophysis secretion provoked by hypothalamic lesion. Natural cytotoxic activity was markedly increased after ETG located either in AH, or MH, or PH. These results indicate that NK- and NC-mediated immunity is governed by a control mechanism situated in the hypothalamus.

Animals↗
PubMed1986

Tumour inhibition by interleukin-2 at the tumour/host interface.

Until recently, lymphokines were regarded suspiciously as 'ill-defined factors'. Today, however, some of them have been clearly defined in both structural and functional terms. The interleukin-2 (IL-2) molecule and its specific membrane receptors have been the subject of particular attention. Endogenous IL-2 has proved to be an important signal for the activation and expansion of various cell-mediated immunity functions, while exogenous IL-2 has been used to activate numerous cell functions, both in vitro and in vivo, as well as in tumour immunotherapy, both alone or combined with lymphocytes previously activated in vitro (lymphokine-activated killer cells). Adoptive transfer of these cells together with high doses of IL-2 is particularly promising from the clinical standpoint, though by no means free from problems. IL-2 can also be employed in small doses locally in the presence of non-activated lymphocytes from tumour bearing mice to induce a local reaction that subsequently becomes systemic and can lead to the rejection of incipient tumours. Various host immune cells, primarily eosinophils and lymphocytes are involved in this reaction, which can also give rise to tumour-specific immune memory. In this way, the host immune system, despite its inevitable defeat in the first battle against a tumour, may acquire an important role in the long war that lies ahead.

Animals↗