Biomedical subjects

H L Mathews

Publications and source records attributed to H L Mathews.

At least 19 recordsLinked to original sources

PubMed2001

Human thymic epithelial cells inhibit IL-15- and IL-2-driven differentiation of NK cells from the early human thymic progenitors.

T/NK progenitors are present in the thymus; however, the thymus predominantly promotes T cell development. In this study, we demonstrated that human thymic epithelial cells (TEC) inhibit NK cell development. Most ex vivo human thymocytes express CD1a, indicating that thymic progenitors are predominantly committed to the T cell lineage. In contrast, the CD1a(-)CD3(-)CD56(+) NK population comprises only 0.2% (n = 7) of thymocytes. However, we observed increases in the percentage (20- to 25-fold) and absolute number (13- to 71-fold) of NK cells when thymocytes were cultured with mixtures of either IL-2, IL-7, and stem cell factor or IL-15, IL-7, and stem cell factor. TEC, when present in the cultures, inhibited the increases in the percentage (3- to 10-fold) and absolute number (3- to 25-fold) of NK cells. Furthermore, we show that TEC-derived soluble factors inhibit generation of NK-CFU and inhibit IL15- or IL2-driven NK cell differentiation from thymic CD34(+) triple-negative thymocytes. The inhibitory activity was found to be associated with a 8,000- to 30,000 Da fraction. Thus, our data demonstrate that TEC inhibit NK cell development from T/NK CD34(+) triple negative progenitors via soluble factor(s), suggesting that the human thymic microenvironment not only actively promotes T cell maturation but also controls the development of non-T lineage cells such as the NK lineage.

Antigens, CD34↗

PubMed2001

Aberrant nuclear expression of AP-1 and NFkappaB in lymphocytes of women stressed by the experience of breast biopsy.

We have investigated the expression of AP-1 and NFkappaB in peripheral blood lymphocytes of women scheduled for breast biopsy. Samples were collected when women were informed of the need for biopsy (prebiopsy, T1, 5-7 days prior to the actual biopsy) and 7-10 days after they learned the result of their biopsy (postbiopsy, T2). At the time of blood collection, psychological stress was evaluated using Speilberger's State Trait Anxiety Inventory (STAI) and the Profile of Mood States (POMS). Women scheduled to undergo breast biopsy reported significant increases in anxiety (STAI) and mood disturbance (POMS). Gel shift mobility assays showed that mitogen stimulated peripheral blood lymphocytes of these women were less capable of the nuclear expression of AP-1 or NFkappaB at T1. Similar assessments, 7-10 days after the women learned of the results of their breast biopsy, showed these same women to have a marked reduction in anxiety and mood disturbance and an increased nuclear translocation of AP-1 and NFkappaB. These results show a significant decrease in nuclear AP-1 and NFkappaB expression during the period of emotional distress prior to biopsy with a return of nuclear transcription activity to normal levels when distress was relieved. Several studies have correlated increased psychological stress with decreased immune function. The results of this study suggest that psychological stress may mediate immunosuppression by altering the expression of the transcription factors, AP-1 and NFkappaB.

Biopsy↗

PubMed2000

Reduced levels of Hsp70 result in a therapeutic effect of 15-deoxyspergualin on acute graft-versus-host disease in (DA x LEW)F1 rats.

We have shown previously that increased levels of hsp70, and antibodies reactive with hsp70 parallel the onset and severity of graft-versus-host disease (GVHD) in a parent --> (DA x LEW)F1 rat model. In this study we have assessed the effect of reducing the levels of the 70 kDa heat shock protein (hsp70), on the morbidity and mortality of acute GVHD in (DA x LEW)F1 rats. The reduction was accomplished by the administration of 15-deoxyspergualin (DSG), an immunosuppressive agent which binds to a constitutively expressed member of the 70 kDa heat shock protein family. DSG administered via three different protocols reduced GVHD-associated morbidity. One of the regimens, which consisted of intermittent DSG administration, also significantly reduced GVHD associated mortality. This DSG treatment reduced hsp70 levels in spleen and lymph nodes, inhibited anti-hsp70 antibody production, and diminished the serum levels of IL-2, IFN-gamma, TNF-alpha, and IL-10. IL-4 levels in the serum did not change during GVHD and were not effected by DSG. These results show that the mechanism of DSG immunosuppressive effect in rat GVHD may involve DSG's capacity to bind to hsp70, which in turn may lead to a decrease in levels of circulating anti-hsp70 antibodies, and reduced production of cytokines.

Acute Disease↗

PubMed1999

Reduced capacity of neonatal lymphocytes to inhibit the growth of Candida albicans.

Opportunistic microorganisms produce significant morbidity and mortality in preterm and term infants. Because of the heightened susceptibility of infants to opportunistic fungal infections, neonatal lymphocytes were assessed for their capacity to inhibit the growth of Candida albicans. Lymphocytes from both preterm and term cord blood demonstrated significantly less effect upon C. albicans than did lymphocytes from adults. Neonatal lymphocytes of infants <32 weeks of gestation showed a marked reduction in growth inhibitory capacity compared to infants >32 weeks of gestation. Lymphocytes from female infants had a significantly greater fungal growth inhibitory capacity than did lymphocytes from male infants. These results show that neonatal lymphocytes have a reduced capacity to inhibit the growth of C. albicans. This reduced antifungal capacity may underlie the increased susceptibility of such infants to opportunistic microorganisms, like C. albicans.

Adult↗

PubMed1999

Differential effects of glucocorticoids on colony stimulating factors produced by neonatal mononuclear cells.

The purpose of this study was to examine the effect of dexamethasone (DEX) on the production of granulocyte and granulocyte-macrophage colony stimulating factors (G-CSF and GM-CSF) by neonatal mononuclear cells. Mononuclear cells were isolated from umbilical cord blood and cultured with either phorbol myristate acetate/phytohemagglutinin (PMA/PHA) or Candida albicans with or without DEX (10(-8)-10(-6) M) for 48 h. Cell supernatants were assayed for G-CSF and GM-CSF by ELISA. Mononuclear cells from term and preterm infants responded to PMA/PHA stimulation with a significant increase in G-CSF production over baseline levels. The PMA/PHA-induced increase in G-CSF production was markedly augmented by the addition of DEX to cell cultures. DEX augmented production of G-CSF was significantly less in mononuclear cells from preterm infants. Similarly, production of G-CSF was significantly less by mononuclear cells from infants with acute physiology scores of > or = 10, as judged by the Score for Acute Neonatal Physiology. In contrast, DEX significantly inhibited PMA/PHA-induced GM-CSF production. Although C. albicans induced mononuclear cells to produce G-CSF, DEX did not significantly augment this production. No significant effect of DEX on C. albicans induced GM-CSF production was observed. The data show DEX induced differential regulation of infant peripheral blood mononuclear cell production of G-CSF and GM-CSF. These results suggest that glucocorticoids may enhance certain aspects of host immune function in addition to their well-documented immunosuppressive effects. Further, the neutrophilia observed in DEX-treated infants may be due to enhanced G-CSF production.

Candida albicans↗

PubMed1998

Expression of 70-kDa heat-shock protein during acute graft-versus-host disease.

Acute lethal graft-versus-host disease (GVHD) was induced in unirradiated (LEW x DA)F1 rats by injection of DA parental lymphoid cells. Control rats received the same dose of (LEW x DA)F1 cells. The level of hsp70 at different stages of GVHD was examined in the spleen, lymph nodes, thymus, liver, lung, kidney, heart, and skeletal muscles of GVHD and control animals. Hsp70 was present in all organs analyzed in both groups and, with the exception of the spleen and lymph nodes, detectable levels remained constant during the disease. However, the spleen and lymph nodes of GVHD rats showed distinct changes in the hsp70 levels throughout the course of the disease. Expression of hsp70 in spleen and lymph nodes was augmented 7 and 14 days after induction of the disease. During the last stages of GVHD, 18-21 days after the induction, expression of hsp70 diminished to a level similar to that in untreated and control animals. Elevated levels of hsp70 in lymphoid organs during GVHD suggest an involvement of hsp70 in the pathology of the disease.

Acute Disease↗

PubMed1998

Effect of d-fenfluramine on the lymphocyte response of HIV+ humans.

The objective of this study was to analyse the effect of d-dexfenfluramine (d-FEN) on the human lymphocyte response, in vitro. Experiments were designed to determine whether d-FEN augments specific human immune parameters associated with protection from opportunistic microbial pathogens and particularly focuses on d-FEN as a means by which to augment the function of CD8+ and CD4+ lymphocytes. Lymphocytes were examined for three reasons: (1) for their ability to inhibit the growth of Candida albicans; (2) for their ability to proliferate in response to a mitogen; and, (3) their cytokine profile (vis., production of IL-2, IFN-gamma and TNF-alpha). Peripheral blood mononuclear cells (PBMC) were obtained from 20 HIV+ patients. The patients were diagnosed as HIV+ within the past 0.5-9 years. d-FEN was found to augment the capacity of CD8+ lymphocytes to inhibit the growth of the opportunistic microbial pathogen, C. albicans. d-FEN enhanced the capacity of CD4+ lymphocytes to proliferate in response to the mitogen, Concanavalin A, and to increase the amount of IL-2 produced by CD4+ and CD8+ lymphocytes from AIDS patients. d-FEN increased the number of CD4+ and CD8+ lymphocytes that produced IFN-gamma from either non-AIDS or AIDS patients and increased the number of AIDS patient's CD8+ lymphocytes that produce TNF-alpha. These in vitro data suggest that d-FEN may be effective in enhancing immune function in immunocompromised individuals.

Adjuvants, Immunologic↗

PubMed1998

Human immune cells mediate catecholamine secretion from adrenal chromaffin cells.

OBJECTIVES: To determine the ability of human mononuclear cells to produce factors that cause catecholamine secretion from adrenomedullary chromaffin cells; to determine conditions that stimulate mononuclear cells to produce such factors; and to compare these results with catecholamine secretion in response to the cytokines interleukin (IL)-1 and IL-2. DESIGN: Randomized, controlled, prospective study using in vitro conditions. SETTING: University research laboratory. SUBJECTS: Human mononuclear cells and porcine chromaffin cells. INTERVENTIONS: Circulating human mononuclear cells were isolated and cultured overnight in RPMI media. Cell-free media from these cultures (conditioned media) were then tested for the ability to cause epinephrine secretion from porcine chromaffin cells. Mononuclear cells were stimulated with phytohemagglutinin or by mixing cells from two different individuals while suppression was tested with dexamethasone. Catecholamine secretion in response to IL-1 and IL-2 (50 and 500 units/well, respectively), or nicotinic agonist dimethylphenylpiperazinium (10 microM, which mimics the action of acetylcholine), was tested for comparison. MEASUREMENTS AND MAIN RESULTS: Isolated porcine chromaffin cells had stable catecholamine content at the time of secretion measurements, and catecholamine release from cells into the media was measured using electrochemical detection after high-performance liquid chromatography separation. Catecholamine secretion was expressed as a percentage of the total cellular content. Epinephrine secretion due to human conditioned media was 6.9 +/- 1.0% compared with 1.4 +/- 0.6% for control media (p < .05) and 14.6 +/- 3.3% for dimethylphenylpiperazinium (p < .05). Epinephrine secretion with conditioned media from mixed cells (mixed leukocyte reaction) was 16.6 +/- 1.2%, which was higher than the epinephrine secretion caused by media from a single donor (6.9% +/- 1.0, p < .001). Pretreatment with dexamethasone inhibited the formation of bioactive products from mixed mononuclear cell preparations. Cytokines IL-1 and IL-2 did not stimulate chromaffin cell epinephrine secretion above background release with control media incubation. In all cases, norepinephrine secretion was similar to that of epinephrine, and results are included in all figures. CONCLUSIONS: Factors released from human immune cells can mediate epinephrine and norepinephrine release from adrenomedullary cells through a nonneural mechanism. Such immune cell factor release can be modulated by immunostimulation and steroid suppression. Release of such factors in vivo may contribute to increased circulating epinephrine in response to infectious challenge and may be an important factor in the critically ill patient.

Animals↗

PubMed1998

Antifungal activity of interleukin-2-activated natural killer (NK1.1+) lymphocytes against Candida albicans.

Interleukin-2 (IL-2)-activated lymphocytes interact directly with, and inhibit, the growth of Candida albicans hyphae. C. albicans-stimulated natural killer (NK1.1+) lymphocytes were demonstrated to secrete a soluble product capable of directly affecting C. albicans yeast forms. Antibodies specific for interferon-gamma completely eliminated the antifungal activity of the NK1.1+ lymphocyte product and diminished the antifungal activity of NK1.1+ lymphocytes against C. albicans. Antibodies specific for other cytokines had no such effect. These data demonstrate that C. albicans-stimulated NK1.1+ lymphocytes have antifungal activity against C. albicans yeast cells via the release of interferon-gamma. This antifungal activity was demonstrable only against the yeast form of the fungus, with no effect on C. albicans hyphae.

Animals↗

PubMed1998

Effect of Pichia anomala killer toxin on Candida albicans.

The effect of a Pichia anomala killer toxin upon a Candida albicans-sensitive strain was studied. Yeast and hyphae, after treatment with the toxin, were less capable of uptaking either [3H]-uridine or [35S]-methionine. In addition, the hyphal form of the fungus appeared to be less capable of DNA synthesis after toxin treatment. No effect of the killer toxin was shown upon a natural resistant mutant of the source strain. These data suggest that, similar to other killer yeast toxins, the toxin of P. anomala can produce a number of quantifiable effects upon sensitive C. albicans cells.

Candida albicans↗

PubMed1997

Induction of apoptotic cell death in a neuroblastoma cell line by dibucaine.

Dibucaine, a local anesthetic known to interact with cell membranes, induced apoptosis in SK-N-MC human neuroblastoma cells in a dose-dependent manner. Apoptosis was demonstrated by direct visualization of morphological nuclear changes using a DAPI staining technique and confirmed by the production of characteristic ladder patterns of DNA fragmentation on gel electrophoresis. At concentrations which induced apoptosis, dibucaine significantly altered membrane fluidity, indicating that fluidity may be a major target for the cytotoxic action of dibucaine. Also, dibucaine increased intracellular calcium levels more effectively in calcium-containing Krebs-Ringer buffer than in calcium-free Krebs-Ringer buffer. Removal of extracellular calcium or addition of antioxidants or protein synthesis inhibitor effectively blocked dibucaine-induced apoptosis. These results suggest that membrane damage, intracellular calcium levels, and oxygen free radicals may be involved in the apoptosis induced by dibucaine.

Anesthetics, Local↗

PubMed1996

Lymphocytes utilize CD11b/CD18 for adhesion to Candida albicans.

Large granular lymphocytes require adherence to hyphae of Candida albicans to inhibit growth of this fungus. This study was undertaken to identify the lymphocyte surface structures that mediate this adhesion. Monoclonal antibodies specific for epitopes of the alpha subunit (CD11b) and the beta 2 subunit (CD18) of Mac-1 eliminated lymphocyte adhesion to C. albicans hyphae. Significant inhibition of lymphocyte adhesion to C. albicans was also achieved with known protein ligands of Mac-1. These proteins included the extracellular matrix proteins vitronectin, laminin, and fibrinogen as well as two engineered peptides containing RGD (arginine-glycine-aspartic acid) sequences. Carbohydrates including N-acetyl-D-glucosamine which have been demonstrated to inhibit Mac-l-mediated adhesion to whole yeast and yeast zymosan also blocked lymphocyte adhesion to hyphae. These results identify Mac-1 (CD11b/CD18) as the surface structure that mediates lymphocyte adhesion to C. albicans. A model is proposed for lymphocyte Mac-1 activation by microbial ligands.

Amino Acid Sequence↗

PubMed1996

Effect of d-fenfluramine on the local immune response to the opportunistic microbial pathogen Candida albicans.

In this study the effects of systemic administration of d-fenfluramine on the local lymphocyte response to Candida albicans was evaluated. Experimental animals were challenged intradermally with Candida albicans and then administered d-fenfluramine (d-FEN 1 mg/kg per day, i.p.) or a balanced salts solution. At successive time intervals, lymphocytes were derived from the draining lymph nodes and from the dermal sites of active microbial challenge. A CD8+ lymphocytosis was observed in all animals challenged with Candida albicans. The CD8+ lymphocytosis was augmented in animals that received d-FEN. Phenotypically, lymph nodes from d-FEN treated animals showed a marked increase in CD3+ and CD8+ lymphocytes, a modest increase in the numbers of NK1.1+ cells and a decrease in Ig+ lymphocytes. Functionally, lymphocytes from the site of active microbial challenge were capable of direct growth inhibition of Candida albicans. The anti-fungal activity was augmented in the animals that received d-FEN. These results suggest that d-FEN augments the local T lymphocyte response to an important microbial pathogen by increasing the number of T lymphocytes draining the site of microbial infection and by increasing the biological activity of the lymphocytes at the site of the infection.

Animals↗

PubMed1995

Growth inhibition of Candida albicans hyphae by CD8+ lymphocytes.

We have shown previously that IL-2-activated splenocytes can inhibit the growth of Candida albicans hyphae in vitro. Herein we demonstrate that plastic nonadherent lymphocytes that are CD8+ mediate the antifungal activity. Enrichment for CD8+ cells markedly enhanced the antifungal activity of the IL-2-activated lymphocyte population for C. albicans and the cytotoxic activity of the lymphocytes for an NK-resistant cell line. Depletion of CD8+ cells reduced the lymphocyte population's antifungal activity and cytotoxic activity for the NK-resistant cell line. Enrichment for NK1.1+ cells markedly reduced the antifungal activity of the lymphocyte population for C. albicans and increased the cytotoxic activity of the lymphocytes for an NK-sensitive cell line. Depletion of NK1.1+ cells increased the lymphocyte population's antifungal activity and cytotoxic activity for the NK-resistant cell line. Generation of the antifungal lymphocytes in culture required IL-2 and was not replaced with IFN-gamma. These data show that IL-2-activated CD8+ T lymphocytes exert the greatest amount of antifungal effect against the hyphal form of C. albicans, whereas IL-2- or IFN-gamma-activated NK cells have little or no effect against the hyphae.

Animals↗

PubMed1995

Suppression of the functional activity of IL-2-activated lymphocytes by CGRP.

CGRP is a 37-amino acid neuropeptide found in the central and peripheral nervous systems as well as the nerve endings in lymphoid organs. Specific CGRP receptors are present on both T and B lymphocytes. There is increasing evidence that CGRP plays a role in regulation of the immune response. However, few investigations have examined the effects of CGRP on lymphocyte effector functions. In this report, CGRP (0.1 nM-1 microM) was shown to cause concentration-dependent inhibition of IL-2-activated lymphocyte growth inhibition of the fungus Candida albicans and cytotoxic activity for tumor cells. Maximum inhibition of lymphocyte activity by CGRP was 47.4% for the hyphae of C. albicans, 44.8% for a natural killer cell susceptible cell line, and 52.9% for a natural killer cell-resistant cell line. CGRP-mediated inhibition of lymphocyte function was mimicked by 8-bromo-cAMP (1 mM) and was correlated in a concentration-dependent manner with an increase in intracellular levels of cAMP. These increases were potentiated by pretreatment of the lymphocytes with 3-isobutyl-1-methylxanthine (0.5 mM, 10 min), an inhibitor of the cAMP phosphodiesterase. hCGRP 8-37, a selective blocker of the CGRP1 receptor, abrogated the effect of CGRP on lymphocyte function and on intracellular cAMP level elevation induced by rCGRP. CGRP had no direct effect on the capacity of IL-2-activated lymphocytes to adhere to the hyphae of C. albicans. However, both CGRP and 8-bromo-cAMP diminished the capacity of the lymphocytes to release cytoplasmic granular content when stimulated by the hyphae of C. albicans. These data show that CGRP inhibits functional activity of IL-2-activated lymphocytes and suggest that hCGRP8-37 may be a useful tool for assessing the role of CGRP in the immune system.

Animals↗

PubMed1995

Antibodies specific for the 70-kDa heat-shock protein parallel the development of acute graft-versus-host disease in (DA x LEW)F1 rats.

Acute GVHD was induced in unirradiated (DA x LEW)F1 rats by the injection of parental DA lymphoid cells. Serum sequentially derived from such animals was found to contain increased levels of antibodies reactive with 70-kDa heat-shock protein (hsp70). Elevated levels of antibody to hsp70 were detected as early as 7 days and were maximal 14 days after the induction of GVHD. These increased levels of antibodies reactive with hsp70 paralleled the onset of the signs and symptoms associated with the development of GVHD. Increased anti-hsp70 reactivity in GVHD sera was associated statistically with increased levels of hsp70-reactive IgM, IgG2a, and IgG2b. In addition, GVHD sera reacted with a 70-kDa protein found within (DA x LEW)F1 lymphoid tissue. These results demonstrate that increased levels of antibodies to hsp70 parallel the onset and development of GVHD in an acute model and are the first to show that antibodies reactive with hsp70 are associated with an ongoing disease process.

Animals↗

PubMed1995

Direct antimicrobial activity of T cells.

T cells are generally thought to contribute to antimicrobial activity either by releasing lymphokines, which recruit and activate other cell types, or by major histocompatibility complex (MHC)-restricted lysis of infected host cells. Recently, it has become apparent that T cells can also mediate antimicrobial activity by direct interaction with microbial targets. Such interactions, which can be either antigen specific or nonspecific, occur in the apparent absence of MHC restriction and do not require the presence of other host cells. Microbial targets recognized by T cells include fungi, parasites and bacteria. Here, Stuart Levitz, Herbert Mathews and Juneann Murphy discuss the direct antimicrobial activity of T cells and speculate on its in vivo relevance.

Animals↗

PubMed1994

CGRP in the serum of endotoxin-treated rats suppresses lymphoproliferation.

Mouse mesenteric lymph node cells were incubated with concanavalin A (Con A) with or without the rat form of calcitonin gene-related peptide (rCGRP) (0.1 fM-1 microM) +/- human (h)CGRP8-37 (1 microM) for 48 h. DNA synthesis was assessed by [3H]thymidine incorporation. Con A-stimulated DNA synthesis was suppressed by 13, 20, and 30% at 10 fM, 1 pM, and 100 pM of rCGRP, respectively. hCGRP8-37 (1 microM), a selective blocker of CGRP1 receptor, completely inhibited the suppression of DNA synthesis by rCGRP (10 fM-100 pM). rCGRP caused concentration-dependent elevations of cAMP levels, which were potentiated by pretreatment with 3-isobutyl-1-methylxanthine (0.3 mM, 10 min), an inhibitor of cAMP-phosphodiesterase. hCGRP8-37 (1 microM) significantly inhibited cAMP elevations induced by rCGRP at the lower concentrations, but not at the highest concentrations of rCGRP. These data suggest that rCGRP, at circulating levels (1-10 pM), appears to directly interact with receptors on mouse mesenteric lymph node cells that are coupled to cAMP generation, ultimately inhibiting lymphocyte proliferation. To test the involvement of CGRP in suppression of lymphocyte proliferation by serum from endotoxin-treated rats, mouse mesenteric lymph node cells were stimulated with Con A with or without dilutions of endotoxin treated rat serum. At a 1:20 dilution, DNA synthesis was suppressed 30%, at a 1:40 dilution, DNA synthesis was suppressed by 34%, and at a 1:80 dilution, DNA synthesis was suppressed 25%. At all serum dilutions, coincubation with hCGRP8-37 (1 microM) significantly inhibited the suppressive effect of the endotoxin treated rat serum. These data suggest that the immunosuppression observed during endotoxin shock may be due, at least in part, to CGRP in serum.

Animals↗