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Biomedical subjects

N Lahat

Publications and source records attributed to N Lahat.

At least 55 records · Page 3Linked to original sources
PubMed1993

Control of HLA-DR antigen expression by gamma-interferon: separate signal transduction mechanisms in malignant and nonmalignant human thyroid cells.

Three intracellular signal transduction pathways have been found to be utilized by gamma-interferon (IFN-gamma) in the induction of HLA-DR in several cell types, mainly monocytes/macrophages and B-cells: the protein kinase A (PKA); Ca(2+)-calmodulin; and protein kinase C (PKC) pathways. In this study, we investigated the role of these pathways in IFN-gamma-induced HLA-DR expression in normal and neoplastic human thyroid cells. The PKA pathway seemed to inhibit both neoplastic and normal IFN-gamma-induced HLA-DR expression; addition of thyroid-stimulating hormone to normal thyroid cells, as well as 8-bromo cyclic AMP and forskolin to normal and neoplastic cells, reduced the amount of IFN-gamma-induced HLA-DR. Moreover, H-8, a PKA inhibitor, enhanced such IFN-gamma-induced HLA-DR expression. The calcium-calmodulin pathway does not seem to play a role in IFN-gamma-induced HLA-DR expression in normal and neoplastic thyrocytes, since the Ca-ionophore A23187, EGTA, and the calmodulin antagonist, W-7, neither induced HLA-DR nor showed any effect on HLA-DR expression induced by IFN-gamma. Alone, phorbol 12-myristate 13-acetate, a PKC activator, did not induce HLA-DR on thyroid cells. However, its addition to neoplastic cells together with IFN-gamma caused a synergistic elevation of the expressed HLA-DR, whereas it significantly inhibited IFN-gamma-induced HLA-DR in normal thyrocytes. TPA had to be added before or together with IFN-gamma for optimal function. If added more than 6 h after IFN-gamma, TPA was not effective. An inactive TPA analogue did not affect HLA-DR induction, while an active analogue mimicked TPA. Staurosporine, a PKC inhibitor, reduced the TPA enhancing effect in neoplastic thyrocytes and cancelled TPA inhibition in normal cells. Moreover, when added to IFN-gamma without TPA in normal thyroid cells, staurosporine increased 3- to 4-fold the amount of HLA-DR. Thus, in normal thyroid cells the PKC pathway is activated by IFN-gamma and inhibits HLA-DR expression. In neoplastic thyrocytes, although IFN-gamma does not induce HLA-DR via PKC, this pathway augments HLA-DR expression.

Alkaloids↗
PubMed1993

HLA-DR alpha gene regulation in immortalized human thyroid cancer cells.

The induction of HLA class II antigens on human thyroid epithelial cells has been shown to be an intimate part of the pathology of autoimmune thyroid disease and may also be relevant to the natural history of thyroid neoplasia since thyroid cancer cells may show spontaneous HLA class II antigen expression. We have, therefore, analyzed the regulation of HLA-DR-alpha-specific mRNA transcripts, as a model for HLA class II antigen induction, in three established human thyroid cancer cell lines (papillary thyroid cell line NPA, and follicular thyroid cell lines RO-82-W1 and MRO-87-1). Each of the lines expressed 1.4 kb HLA-DR-alpha-specific mRNA transcripts, either constitutively or after cytokine induction, but showed markedly different regulatory characteristics. For example, the induction of HLA-DR alpha mRNA in response to recombinant human interferon-gamma (IFN-gamma) was inversely proportional to the degree of constitutive DR alpha mRNA expression; when there was constitutive absence there was a greater degree of induction. Similarly, the half-lives of the HLA-DR alpha mRNA transcripts varied from 80 to 420 min with the longest degradation time occurring in those cells lacking constitutive expression of HLA-DR alpha mRNA. These data indicated that the degradation rate was not a determinant of their constitutive expression. We also sequenced the 5' promoter region of the HLA-DR alpha gene (nucleotides -88 to -277 with respect to the translation start site) in each of the three cell lines. Sequence analyses revealed identity to the previously published normal human genomic sequence. Taken together, therefore, these data indicate that transactivating factors, rather than changes in mRNA degradation or promoter abnormalities, are the likely causes of variation in constitutive and cytokine-induced HLA-DR alpha gene expression in human thyroid cancer cells.

Adenocarcinoma↗
PubMed1993

Differential effects of prolactin upon activation and differentiation of human B lymphocytes.

The effects of human prolactin on enriched peripheral B lymphocytes obtained from healthy males were examined. Immunoregulation by prolactin was studied in B cells activated with either anti-IgM alone, or anti-IgM antibodies and recombinant interleukin-2 (r-IL-2), as well as control resting B cells. Expression of IL-2 receptors (IL-2R), and IgM and IgG in the culture supernatants were used as a measure of B cell activation and differentiation. Prolactin significantly synergized with IL-2 in the enhancement of surface expression of IL-2R on anti-IgM treated B cells. Although no differentiating effect was observed on resting B cells, prolactin (0.2-100 ng/ml) exhibited a dose-dependent enhancement upon both IgM and IgG secretion from B cells treated with anti-IgM and IL-2. In the absence of exogenously added IL-2 similar differentiating effect were observed in B cells treated with anti-IgM at prolactin concentrations of 0.2-10 ng/ml, but not 100 ng/ml. Thus, the present results demonstrate the modulatory effect of prolactin on activation and differentiation of anti-IgM triggered human B cells, and emphasize the importance of co-stimulatory signal mediated by IL-2 in B cell responses to high prolactin levels. These findings extend the immunoregulatory effects of prolactin, previously confirmed for T cells, to the B cell arm of the immune response, and suggest an important role of prolactin in mediating adaptation and communication between the nerve and immune systems.

Adult↗
PubMed1993

Vitiligo, rheumatoid arthritis and pernicious anemia.

A patient with a 46-year history of vitiligo who also presented rheumatoid arthritis and pernicious anemia is described. Meticulous physical examination excluded further systemic or cutaneous involvement. The immunological workup revealed a low CD4 cell percentage with T cells mostly composed of CD8 cells, a discrepancy between the high percentage of cumulative CD4 + CD8 cells and the measured CD3 proportions, very low NK cytotoxicity toward K562 cells, and almost negligible responses to PHA, Con A and PWM mitogens. The results point to severe T and NK cell functional defects. The pathogenetic significance of these data is discussed.

Aged↗
PubMed1993

Early IL-2/sIL-2R surge following surgery leads to temporary immune refractoriness.

High serum level of immunoreactive but not biologically active IL-2 was detected 1 day after surgery in patients undergoing major operation (abdominal, open-heart), in proportion to the tissue injury caused by surgical trauma. IL-2 values were highest in those patients who underwent open-heart surgery and received blood transfusions. In all patients they declined in the third and fourth post-operative days. Elevated serum levels of soluble IL-2 receptors (sIL-2R) were already present 1 day after operation, and peaked in the third and fifth post-operative days after mitogen triggering. Blood lymphocytes derived from operated patients secreted reduced amounts of both IL-2 and sIL-2R compared with control lymphocytes. The extent and duration of this reduction were also proportional to the tissue trauma and were affected by blood transfusions. Based on these data we suggest that early post-operative systemic immunological activation (appearance of IL-2 in the serum) is followed by elevation of sIL-2R, which then interferes with IL-2-dependent immunity. Blood lymphocytes are probably not involved in the post-operative immunological activation. The trigger for and the site of IL-2/sIL-2R synthesis are not yet clear.

Adult↗
PubMed1993

Effect of a single exposure to hyperbaric oxygen on blood mononuclear cells in human subjects.

We studied the effect of a single exposure to a therapeutic profile of hyperbaric oxygen on blood mononuclear cell subset. Twenty healthy volunteers were exposed to 0.28 MPa for 90 min. Thirteen breathed pure oxygen and seven were control subjects exposed to compressed air at the same pressure. Venous blood samples were drawn before HBO exposure, immediately on exit from the chamber, and 24 h later. Immediately after the exposure, a significant increase was observed in the percentage and absolute number of CD8 (suppressor/cytotoxic) T cells, with a concomitant decrease in the CD4 (helper/inducer) T cells. These changes resulted in a decreased CD4:CD8 ratio. A rise was also observed in the number of HLA-DR antigen-bearing cells, with a transient increase in monocytes. There was no change in the total count and percentage of T cells (CD3), B cells, and NK cells. Twenty-four hours after HBO exposure there was a partial reversal of the decrease in the mean CD4:CD8 ratio, but it was still significantly lower than preexposure values. The fast reversibility of the change in the CD4:CD8 ratio suggests specific HBO-induced shifts and sequestration of T-cell subpopulations.

Adult↗
PubMed1992

Divergent effects of cytokines on human leukocyte antigen-DR antigen expression of neoplastic and non-neoplastic human thyroid cells.

Apparently complex modulatory effects of alpha-interferon (alpha-IFN), tumor necrosis factor (TNF), and epidermal growth factor (EGF) have been found in neoplastic human thyroid cells, which could possibly affect the final outcome in neoplastic disease. This was achieved by examining the influence of alpha-IFN, TNF, and EGF alone and in combination, on human leukocyte antigen-DR (DR) antigen expression and viability of neoplastic and non-neoplastic human thyroid cells in culture. alpha-IFN-induced DR antigen expression on non-neoplastic human thyroid cells, whereas TNF-alpha or EGF alone were ineffective. The addition of the same TNF-alpha concentrations (10 to 100 ng/ml) to alpha-IFN enhanced the expression of DR antigens compared with the effect of alpha-IFN alone. However, EGF inhibited alpha-IFN-induced DR on the same cells and at the same concentrations (10 to 500 ng/ml) at which the growth factor alone was ineffective. In contrast to the common pattern of cytokine effects on DR expression of all nonmalignant thyroid cell lines, neoplastic thyroid cell lines showed divergent responses to alpha-IFN, TNF-alpha, and EGF. In three malignant thyroid cell lines that were DR negative (follicular carcinoma WRO 82-1 and NRO 87-1 cell lines, and anaplastic carcinoma ARO 81-1), DR antigen could be induced by alpha-IFN and enhanced by TNF-alpha, whereas EGF was ineffective. In a fourth cell line (an anaplastic carcinoma SW1736) alpha-IFN, TNF-alpha, and EGF alone were capable of inducing DR, and a combination of either TNF-alpha and EGF with alpha-IFN potentiated DR induction. In a fifth neoplastic cell line (papillary carcinoma, NPA) that constitutively expressed surface DR, its expression was inhibited by both alpha-IFN and TNF-alpha and was not affected by EGF.

Antibodies↗
PubMed1992

Long-standing dermatological manifestations in a patient with chronic heavy metal intoxication.

A patient with chronic metal intoxication is described, presenting during four years after the cessation of her exposure to industrial substances, maculo-papular eruptions with several ulcerated lesions and excoriations on her abdomen and buttocks. She also had pallor of her face, greyish-dark discoloration of the hair, while the fingernails were brittle and sensitive. Scrupulous physical examination excluded further cutaneous involvement. The immunological workup revealed both phenotypic and functional defects in cellular immunity.

Dermatitis, Contact↗
PubMed1992

Serum levels of IL-1, IL-6 and tumour necrosis factors in patients undergoing coronary artery bypass grafts or cholecystectomy.

Plasma levels of biologically active IL-1, tumour necrosis factor (TNF) and IL-6 were measured before, during and after coronary artery bypass graftings (CABG) (n = 9) and cholecystectomy (CHO, n = 9), and in normal controls (nine healthy volunteers). Mean pre-operative IL-1 concentration in four of the nine CABG patients was 0.452 + 0.03 ng/ml, significantly (P less than 0.001) higher than that of the other five (0.045 +/- 0.009 ng/ml), CHO patients (0.035 +/- 0.005 ng/ml) and controls (0.029 +/- 0.008 ng/ml). Three of the four patients with high pre-operative IL-1 had functional capacity IV, while the other five had functional capacity IIa or IIb. Slight IL-1 elevation after anaesthesia, followed by reduction after initiation of bypass, elevation on completion of surgery and reduction to basal levels after 7 days was found in patients undergoing CABG. Mean basal TNF levels of CABG and CHO patients did not differ, but were higher than those of controls (2.85 +/- 0.5 ng/ml for CABG, 2.05 +/- 0.06 ng/ml for CHO, 0.72 +/- 0.07 ng/ml for normals, P less than 0.001). A unique kinetics of release during CABG was observed also for TNF. Mean pre-operative IL-6 levels were normal (50 +/- 3 ng/ml for CABG, 50 +/- 0.5 ng/ml for CHO and 65 +/- 10 ng/ml for controls). Gradual elevation to a mean peak of 725 +/- 100 ng/ml on completion of CABG was observed as compared with 275 +/- 50 ng/ml in CHO (P less than 0.01). On the seventh post-operative day mean IL-6 levels returned to normal. Two patients with post-operative low-grade fever (38 degrees C) had high, late cytokine levels. One of these two patients had leucocytosis, sterile discharge from the operative wound and was diagnosed as suffering from the Dressler syndrome. In this study elevated cytokine values and unique kinetics of release into the serum were found in patients undergoing CABG.

Adult↗
PubMed1992

Evidence for selective accumulation of intrathyroidal T lymphocytes in human autoimmune thyroid disease based on T cell receptor V gene usage.

We have investigated the T cell receptor V alpha and V beta gene family usage by T lymphocytes infiltrating affected thyroids in patients with autoimmune thyroid disease. We show that the intrathyroidal T lymphocytes from patients (n = 6) with autoimmune thyroid disease display a widespread usage of V beta gene families with an average of 14.4/19 V beta gene families similar to the peripheral T lymphocytes of the same patients. Because we recently reported that the utilization of V alpha gene families is markedly reduced within these mitogen-stimulated intrathyroidal T cell populations, as well as within intact tissue from similar patients (n = 4) (overall mean of 4.0/18 families detected), these results indicate that in thyroids of patients with autoimmune thyroid disease the lymphocytes are selectively accumulating based on their V alpha rather than V beta elements. This preferential hTcR V alpha and widespread V beta gene usage was not mimicked in most 7-d autologous mixed lymphocyte reactions using non-T cell stimulators (n = 6) or EB-virus immortalized autologous B cell lines (n = 3). Hence, the selective V gene utilization by intrathyroidal T cells is likely to be secondary to multiepitopic thyroidal autoantigens activating thyroid infiltrating T cells or to the presence of a superantigenlike thyroidal self-antigen, capable of determining a selective infiltration or activation of a variety of T lymphocytes on the basis of their V alpha gene usage.

Autoantibodies↗
PubMed1992

Divergent effects of thyroid HLA-antigens on T and natural killer (NK) cell cytotoxicity.

We have used non-autoimmune non-neoplastic human thyroid cells to explore the role of surface class I and DR antigens on these cells' sensitivity towards T and Natural Killer (NK) cell cytotoxicity. Non-treated thyrocytes expressed class I but no DR antigens. Following incubation with gamma-interferon (gamma-IFN) class I antigens were markedly elevated and DR expression was induced. Whereas non-treated thyrocytes were minimally lysed by sensitized T cells, they served as appropriate targets for NK cells. Following incubation with gamma-IFN, the thyroid cells became highly sensitive to T cell lysis, with no significant reduction in their vulnerability to NK cell killing. The addition of monoclonal anti class I or DR antigens, or brief acid treatment which specifically eliminates class I molecules, inhibited T cell cytotoxicity but enhanced the sensitivity to lysis by NK cells. Thus, the presence of HLA antigens on the same thyroid cells have an opposite effect on two major cytotoxi mechanisms. Our findings are relevant within the context of recent suggestions of intervening with target HLA antigens for the management of autoimmune and malignant diseases.

Cytotoxicity, Immunologic↗
PubMed1992

Ex vivo secretion of tumor necrosis factor and interleukin-2 by rat splenocytes after intestinal ischemia and shock.

We studied the ex vivo secretion of tumor necrosis factor (TNF) and interleukin 2 (IL-2) by splenocytes after circulatory shock induced by intestinal ischemia and reperfusion in rats. Shock was induced by total occlusion of the superior mesenteric artery followed by reperfusion. In a second group, vascular occlusion was maintained throughout the experimental protocol. A third group of sham rats and a fourth group of control rats with a negligible surgical procedure were also studied. "Spontaneous" (untriggered) secretion of TNF by splenocytes was higher in the ischemia-reperfusion group than in all other groups (p < 0.01), but did not increase significantly after stimulation with LPS. Splenocytes from control rats exhibited a marked increase in TNF secretion after stimulation with LPS to values similar to those in the ischemia-reperfusion group. A diminished, though statistically significant increase in LPS-stimulated secretion of TNF was detected in the sham and ischemia only groups of rats (p < 0.05) from untriggered values in each. Untriggered secretion of IL-2 was similar in all groups. However, when compared to control rats, splenocytes from the three surgically manipulated groups exhibited suppressed secretion of IL-2 in response to stimulation with Con A (p < 0.05). These results support the role played by TNF in mediation of shock and point to spleen macrophages as a source of TNF after intestinal ischemia and reperfusion. Our results also demonstrated postinjury alteration in immune function manifested by depressed ability of splenocytes to increase the production of IL-2 after stimulation with Con A.

Animals↗
PubMed1991

Altered interleukin-2 secretion in patients with primary fibromyalgia syndrome.

Interleukin-2 (IL-2) production was studied in T lymphocytes and isolated CD4+ T lymphocytes from 12 patients with primary fibromyalgia syndrome and 10 healthy volunteers. The dose and time kinetics of IL-2 production by concanavalin A-stimulated T cells and CD4+ T cells of fibromyalgia patients differed from findings in controls by 1) a need for a higher concentration of mitogen in order to achieve optimal IL-2 secretion, and 2) a delay in the peak time of optimal IL-2 secretion. Unlike normal IL-2 secretion, which was higher after removal of CD8+ T cells, the pattern and degree of IL-2 secretion by cells from fibromyalgia patients were not changed following removal of CD8+ T cells. Addition of calcium ionophore in assays using suboptimal concanavalin A concentrations did not correct the reduction in IL-2 secretion by fibromyalgia patient T cells, but addition of phorbol myristate acetate induced normal secretion of IL-2. These findings suggest that there is a defect in the IL-2 pathway, which is related to protein kinase C activation and does not involve impairment of Ca2+ elevation, in patients with fibromyalgia.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1991

Acute release of cytokines is proportional to tissue injury induced by surgical trauma and shock in rats.

Cytokines are important mediators of the inflammatory reaction and microvascular injury after trauma and tissue ischemia. The plasma activity of a cytokine reflects the net effect of positive and negative signals. We examined the sequential serum activity of IL-1, IL-2, IL-6, and TNF in a severe model of splanchnic artery occlusion (SAO) shock induced in rats by total occlusion of the superior mesenteric and the celiac arteries for 40 min. A control group with negligible surgical intervention and two sham-shock groups, one with minor operation and another with major surgery employed in SAO rats, both without vascular occlusion, were also studied. No IL-1 activity was detected throughout the 190-min experimental protocol in any of the groups. Low activity of IL-2 was measured only in SAO rats (approximately 1 U/ml at the peak). We found graded increases in serum TNF and IL-6 activities which were proportional to the surgical trauma and were highest in SAO rats (IL-6 up to 30 U/ml, P less than 0.01 from both sham groups; TNF, 2500 pg/ml 30 min after reperfusion, P less than 0.01 from both sham groups). These data further support the role played by cytokines in the early mediation of surgical trauma and shock.

Animals↗
PubMed1991

Increased spontaneous secretion of IL-6 from B cells of patients with B chronic lymphatic leukaemia (B-CLL) and autoimmunity.

We studied B cells from 18 patients with B-CLL, six of them with autoimmune haemolytic anaemia, for spontaneous secretion of IL-6. Our aim was to determine whether the increased incidence of autoimmune disease found in B-CLL patients is associated with enhanced spontaneous IL-6 secretion. IL-6 was measured by the effect of B cell supernatants on the proliferation of an IL-6 dependent plasmacytoma cell line T1165. The highest IL-6 values (7.4 +/- 1.8 U/ml) were measured in supernatants derived on day 3 of culture from lymphocytes of the six patients with B-CLL and concomitant autoimmune disease. The maximal IL-6 values for 10 patients with B-CLL only were 2.8 +/- 0.3 U/ml and for 10 age-matched controls, 0.8 +/- 0.3 U/ml (P less than 0.01, each group compared with the other). We conclude that there is an association between B-CLL, autoimmune disease and the spontaneous in vitro secretion of IL-6. Further studies are needed to determine whether the IL-6 secretion plays a role in the pathogenesis of autoimmune disease in patients with B-CLL.

Aged↗
PubMed1990

Concomitant effect of 2'-deoxycoformycin on natural killer cell activity and tumour cell sensitivity to lysis in hairy cell leukaemia--discordant effects of alpha interferon.

The effects of 2'-deoxycoformycin (dCF) and alpha interferon (IFN-alpha) on natural killer (NK) cell-enriched fractions and hairy cell (HC) targets from three patients with HC leukaemia (HCL) were investigated. There was no significant increase in NK activity when either the HC targets or NK-enriched cells were preincubated with dCF. However, preincubation of both HC and NK cells with dCF resulted in increased NK activity. Culture of enriched NK cells with IFN-alpha enhanced their activity. However, preincubation of HC targets with this drug in the presence or absence of dCF resulted in a protective effect. Maximal NK activity towards HCL was obtained when the target tumour cells were separately precultured with dCF and the NK-enriched effectors precultured with dCF + IFN-alpha. The effect of dCF and IFN-alpha was also measured using the standard K562 cells as targets for NK activity. dCF enhanced NK activity following preculture of both effector and target K562 cells, but IFN-alpha did not reduce K562 cell susceptibility to NK lysis as it did for HC cells. Our findings suggest that (a) dCF and IFN-alpha, which are used to treat HC, could function via activation of NK cells, (b) effects on both effector and tumour target cells should be taken into account, and (c) caution should be exercised in extrapolating the effects of NK-cell activity against K562 cells to those on HC targets.

Cytotoxicity, Immunologic↗
PubMed1990

Effects of gamma-interferon on DR antigen expression, growth, 3,5,3'-triiodothyronine secretion, iodide uptake, and cyclic adenosine 3',5'-monophosphate accumulation in cultured human thyroid cells.

We have examined, using the same system of human thyroid cells in culture, the effects of the cytokine human gamma-interferon (gamma IFN) on the expression of DR antigen, cell pro-liferation, cAMP accumulation, and the differentiated functions, iodide uptake and T3 secretion. gamma IFN elicited a dose- and time-dependent increase in DR expression, with a maximum effect on day 5 of culture. The cytokine, at the same concentrations and experimental conditions as those found to be effective in inducing DR antigen expression, caused on day 5 of culture a dose-dependent inhibition of [3H]thymidine incorporation, DNA content, cell count, as well as TSH-stimulated (but not basal) iodide uptake and T3 secretion. The gamma IFN suppressive influence on the differentiated functions was not merely due to a reduction in cell number, but was also apparent when results were expressed per micrograms DNA. Since the cytokine did not inhibit TSH- or forskolin-stimulated cAMP accumulation and showed a suppressive influence toward 8-bromo-cAMP- and forskolin-stimulated T3 secretion, its inhibitory effect seems to be exerted at a site located distal to cAMP formation. Although gamma IFN alone was devoid of any effect on cAMP accumulation, it enhanced forskolin-stimulated (as well as TSH-activated) cAMP in the presence of 3-isobutyl-1-methylxanthine, an inhibitor of cAMP degradation. Thus, it would seem that gamma IFN also exerts an influence on cAMP formation (rather than degradation) at a step subsequent to TSH binding to its receptor. The effects we observed seem specific to gamma IFN, since alpha IFN, although capable of inhibiting human thyrocyte multiplication, lacked any influence on DR antigen expression, cAMP accumulation, or T3 secretion by human thyroid cells. In what way, if any, is gamma IFN-induced DR antigen expression on human thyrocytes, an event believed to be critical in the pathophysiology of autoimmune thyroid disease, related to decreased thyroid function and growth is presently unknown.

Cell Count↗