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E Pearlman

Publications and source records attributed to E Pearlman.

At least 55 records · Page 3Linked to original sources
PubMed1995

IL-12 modulation of T helper responses to the filarial helminth, Brugia malayi.

The purpose of the current study was to evaluate the effects of exogenous IL-12 on: 1) development of the Th cell response to Brugia malayi microfilariae (mf); 2) established B. malayi-specific Th2 responses; and 3) resistance to mf. IL-12 given at the time of inoculation with live mf resulted in a switch in development from a dominant Th2 (IL-4, IL-5 >> IFN-gamma) to a dominant Th1 response (IFN-gamma >> IL-4, IL-5). Induction of Th1 activity by IL-12 was dependent on IFN-gamma in vivo. When mice were given IL-12 (0.5 microgram daily for 4 days) after mf Ag-specific Th2 responses had been established, Ag-driven IL-4 and IL-5 production by spleen and peritoneal cells were reduced respectively by approximately 75 to 90% and approximately 30 to 40%, IFN-gamma production was elevated, and 68% fewer eosinophils were recovered from the peritoneal cavity. In vivo depletion of IFN-gamma ablated the effects of IL-12 on both cytokine production and eosinophil recovery. IL-12 treatment of either naive or previously sensitized mice challenged intravenously with live B. malayi did not alter the rate of clearance of mf from the blood. These data indicate that IL-12 treatment suppresses induction of filarial driven Th2 responses and modulates recall responses of established Th2 cells, but does not alter elimination of blood-borne mf in nonimmune or immune mice.

Animals↗
PubMed1993

Modulation of murine cytokine responses to mycobacterial antigens by helminth-induced T helper 2 cell responses.

BALB/c mice inoculated with live Brugia malayi microfilariae (mf), or immunized with a soluble filarial extract (B. malayi Ag (BmA)), develop a pronounced Th2-like response over time. In contrast, single or repeated immunizations with a soluble Mycobacterium tuberculosis Ag preparation (purified protein derivative, PPD) stimulates a Th1, but not Th2 response (IFN-gamma >> IL-4, IL-5). To determine if the Th1 response to PPD can be modulated by the ongoing helminth-induced Th2 activity, mice were: 1) immunized simultaneously with BmA and PPD; 2) immunized first with BmA, then with PPD; or 3) inoculated with live mf and immunized with PPD at various times thereafter. Simultaneous immunization with both Ag had no effect on the Th response induced by PPD, i.e., it was strictly Th1. In contrast, establishment of a Th2 response by either inoculation of live mf or immunization with BmA before administration of PPD skewed the PPD-specific Th response such that IL-4 and IL-5 were produced in addition to IFN-gamma. IL-4 and IL-5 levels produced in response to PPD under these conditions were further elevated in vitro in the presence of neutralizing IFN-gamma. Finally, in vivo neutralization of IL-4 diminished induction of Th2 responses to PPD. These results demonstrate that ongoing Th2 responses to helminth Ag modulate the Th response to mycobacterial Ag by an IL-4 dependent mechanism.

Animals↗
PubMed1993

Brugia malayi: acquired resistance to microfilariae in BALB/c mice correlates with local Th2 responses.

The role of specific Th subsets in the regulation of acquired resistance to the filarial parasite Brugia malayi is not known. We examined pathologic and cytokine responses in filarial antigen-sensitized BALB/c mice inoculated intraperitoneally with live microfilariae. Animals immunized three times with soluble microfilarial antigen demonstrated accelerated clearance of live parasites (12 +/- 5% of parasites recovered from the peritoneal cavity 4 days after inoculation vs 57 +/- 6% in controls, P < 0.001). Elimination of microfilariae by immunized mice was associated with local eosinophilia (1.5 x 10(7) eosinophils/ml peritoneal wash fluid compared with 2 x 10(5) eosinophils/ml in unimmunized animals), development of local eosinophil-containing granulomas, and elevated serum IgE levels (7.0 +/- 1.4 vs 2.1 +/- 0.9 micrograms/ml in controls, P < 0.01). CD4+ cells from the site of parasite challenge produced Th2-associated cytokines exclusively (IL-4 and IL-5, not IFN-gamma and IL-2) in response to Brugia antigen, whereas spleen and lymph node cells produced both Th1- and Th2-associated cytokines. Mice immunized a single time with microfilarial antigen did not clear parasites in this time, and peritoneal exudate cells from these animals produced IFN-gamma but not IL-5. These results indicate that acquired resistance to B. malayi microfilariae in mice is associated with induction of a Th2 and not a Th1 response at the site of parasite elimination.

Animals↗
PubMed1993

Legionella pneumophila replicates within rat alveolar epithelial cells.

Legionella pneumophila replicates in the distal pulmonary airspace, causing legionnaires' pneumonia. Legionella organisms replicate within alveolar macrophages and recruited blood monocytes; however, when these cells are activated, they become potent inhibitors of L. pneumophila proliferation. L. pneumophila may replicate in other cells and thereby avoid the host defenses of macrophages. Experiments demonstrated that L. pneumophila replicate within primary cultures of rat pulmonary alveolar epithelial cells. Double-label immunofluorescent and electron microscopy demonstrated L. pneumophila within epithelial cells. Replication of L. pneumophila required similar numbers of alveolar epithelial cells or alveolar macrophages, required viable epithelial cells, and took place intracellularly. While replication of L. pneumophila occurred in both serum-free and serum-containing media, it was enhanced in the presence of serum. Pulmonary alveolar epithelial cells may represent an alternative site for replication of Legionella species in the terminal airspace and thus clarify some previously unexplained aspects of the pathogenesis of legionnaires' disease.

Animals↗
PubMed1993

Class II major histocompatibility complex molecule expression on murine eosinophils activated in vivo by Brugia malayi.

The Th-2 response to microfilariae of Brugia malayi in BALB/c mice is associated with peritoneal eosinophilia. These eosinophils had an activated hypodense phenotype in vivo and expressed high levels of the class II major histocompatibility complex (MHC). Interleukin 4 up-regulated the class II MHC, whereas gamma interferon inhibited class II MHC expression on eosinophils.

Animals↗
PubMed1993

Induction of murine T-helper-cell responses to the filarial nematode Brugia malayi.

The purpose of this study was to examine the murine T-helper-cell (Th) cytokine response to the human filarial parasite Brugia malayi. In the first 14 days following intraperitoneal inoculation of live microfilariae into BALB/c mice, filarial antigen-driven splenic lymphoid cells produced gamma interferon (IFN-gamma) and little or no interleukin-5 (IL-5). After this time, IL-5 production increased (to 10 to 12 ng per 5 x 10(6) cells) coincident with a marked diminution in IFN-gamma generation. A single subcutaneous immunization with soluble microfilarial antigens also induced an IFN-gamma but no IL-5 response, whereas immunization three times elicited a predominant Th2-like reaction characterized by IL-4 and IL-5 production by CD4+ lymph node lymphocytes and a 10-fold increase in serum immunoglobulin E. The importance of IL-10 in establishing the balance between parasite-specific Th1 and Th2 responses was demonstrated by the ability of neutralizing monoclonal antibody to this cytokine to increase IFN-gamma production by splenic and lymph node cells from mice chronically exposed to live microfilariae or immunized multiple times with soluble filarial antigens.

Animals↗
PubMed1992

Dual mechanisms of potentiation of murine antigen-specific IgE production by cyclosporin A in vitro.

Concomitant administration of cyclosporin A (CsA) with Ag has been shown to augment the production of Ag-specific IgE in vivo. We demonstrate that addition of CsA also markedly potentiated Ag-specific IgE in vitro. Low doses of CsA (3 and 10 ng/ml) added at the time of culture initiation selectively enhanced Ag-specific IgE but not IgA or IgG1 production, whereas higher doses (30 ng/ml) suppressed production of all the isotypes. Augmented IgE production was found to correlate with enhanced production of IL-4 and diminished production of IFN-gamma. Delayed addition (after 2 days) of low doses of CsA to Ag-stimulated cultures did not potentiate IgE production, even though CsA differentially affected levels of IL-4 and IFN-gamma. CsA enhanced Ag-mediated cognate T/B interaction was not affected by neutralizing doses of anti-IL-4, suggesting Ag-mediated lymphocytic "synapses" may be inaccessible to anti-IL-4. The effect of CsA on Ag presentation was determined by pulsing peritoneal exudate cells, spleen cells, or primed B cells with Ag and low doses of CsA before incubation with primed splenocytes. Enhanced Ag-specific IgE responses were detected with no effect on IL-4 or IFN-gamma levels. Thus, our study indicates that CsA potentiation of Ag-specific IgE response is due to cumulative action of CsA on two independent pathways: first, CsA differentially modulates IL-4 and IFN-gamma levels during the early phase of cognate Th2/B cell interaction; and second, CsA directly affects APC and IgE isotype-specific amplifying cellular components without apparently affecting the secretory levels of IL-4 and IFN-gamma. Dual mechanisms of CsA-potentiated IgE production are consistent with the hypothesis of two-tiered T cell regulation of Ag-specific IgE responses.

Animals↗
PubMed1992

Antigenicity of a protective recombinant filarial protein in human bancroftian filariasis.

A 92-kDa fusion protein that encodes amino acids 1-479 of a 62-kDa Brugia malayi antigen induces resistance to microfilariae in mice. The antigenicity of this recombinant protein was explored in asymptomatic residents of Wuchereria bancrofti-endemic areas of Papua New Guinea and Egypt. Unlike sera from individuals in nonendemic areas, sera from residents of endemic areas contained IgG3 antibodies (up to dilution 1:1280) reactive with the fusion protein. There was little or no recombinant antigen-specific IgG1, IgG2, IgG4, or IgE. The mean level of IgG3 antibodies to the amino acid 1-479 construct in sera of putatively "immune" adult Papua New Guineans and children in whom microfilaremia was < 4 parasites/mL of blood was not significantly different (P < .05) from those with > 1000 parasites/mL. These data indicate that the filarial antigen corresponding to the recombinant protein is highly immunogenic in naturally infected children and adults and that the isotype and magnitude of antibody reactivity with it do not correlate with the microfilaremic status of asymptomatic persons.

Adolescent↗
PubMed1991

Cross-reactive Legionella antigens and the antibody response during infection.

In order to define cross-reactive Legionella antigens suitable for diagnostic purposes, we investigated sonicate antigens from two Legionella species, including two serogroups of L. pneumophila. The antigens were reacted with heterologous and homologous rabbit antisera in Western blot. Sera from seven patients with culture-verified L. pneumophila infection and nine patients with serologically confirmed L. micdadei infection were also investigated for reactivity with the corresponding antigens. Among the cross-reactive Legionella antigens defined, non-specific reactivity in patients' sera with the 58-kDa common antigen (CA) was noted. Specific reactions were observed with the Legionella flagellum antigen and with the macrophage infectivity potentiator (Mip) protein; with both antigens, however, the reactive sera were too few to suggest the use of a single antigen in a diagnostic test.

Animals↗
PubMed1990

Protective efficacy of a cloned Brugia malayi antigen in a mouse model of microfilaremia.

Immunization of mice with irradiated Brugia larvae or parasite extracts has been shown to induce partial resistance to microfilaremia and enhance clearance of infective larvae. We recently reported the cloning of a 548 amino acid 62-kDa Brugia malayi Ag identified on the basis of reactivity with antisera to a subset of protective microfilarial Ag. Our study describes the protective efficacy against microfilaremia in mice, immunogenicity, and parasite stage-specificity of this candidate vaccine molecule. Immunization of Swiss or BALB/c mice with 1 to 3 micrograms of a 92-kDa trpE fusion protein encoding amino acids 1-479 reduced the intensity of microfilaremia by 40 to 60% compared to control animals given buffer or bacterial trpE (p less than 0.01 to 0.001). Mice immunized with the 92-kDa fusion protein developed delayed-type hypersensitivity reactivity to B. malayi as assessed by enhanced footpad swelling 24 and 48 h after intradermal injection of adult worm extract and in vitro lymph node mononuclear cell proliferation (3H-thymidine uptake) in response to the fusion protein (mean +/- SD stimulation index 4.7 +/- 0.8 vs 2.0 +/- 1.4 for trpE, p less than 0.05). Proliferative responses of lymph node cells coincubated with three other fusion proteins corresponding to the filarial protein truncated from its carboxyl-terminus suggest that dominant T cell epitopes of the 62-kDa Ag are encompassed by amino acids 437-479. Rabbit antibody to the 92-kDa trpE fusion protein immunoprecipitated a 62-kDa polypeptide from [35S] methionine biosynthetically labeled B. malayi microfilariae, adult female, and adult male worms. These data indicate that a recombinant Ag expressed in several developmental stages of B. malayi is capable of inducing partial resistance against microfilariae and Ag-specific T cell responses in mice.

Animals↗
PubMed1988

Growth of Legionella pneumophila in a human macrophage-like (U937) cell line.

We established a model of the bacteria-macrophage interaction to study the cellular basis of Legionella pneumophila pathogenesis and to characterize avirulent L. pneumophila. We found that U937 cells, which are derived from a human histiocytic lymphoma cell line, support intracellular growth of L. pneumophila with a doubling time of 6 h, and that sustained intracellular growth is associated with a cytopathic effect (CPE) that can be detected by microscopic examination and quantified with the vital stain 3-(4,5-dimethyl thiazol-2-yl)-2,5,-diphenyl tetrazolium bromide (MTT). An L. pneumophila isolate obtained directly from infected guinea-pig spleens can grow and produce CPE in these cells, destroying most of the cell layer after 72 h of growth. Only 10(6) organisms of this strain are required to kill 50% of guinea-pigs inoculated by the intraperitoneal route. In contrast, an avirulent isolate derived by 203 successive plate passages of the same strain can neither kill guinea-pigs at an intraperitoneal inoculum of 10(7) nor grow or produce CPE in U937 cells. Since the cells were able to differentiate between a virulent and an avirulent strain of L. pneumophila, we conclude that U937 cells are an appropriate model system for study of the bacteria-macrophage interaction.

Animals↗
PubMed1986

Antibodies isolated by using cloned surface antigens recognize antigenically related components of Legionella pneumophila and other Legionella species.

We studied the antigenic cross-reactivity of surface proteins among various strains of Legionella pneumophila and other Legionella species by using a novel method of antibody purification. Anti-bacterial antibodies in hyperimmune sera were adsorbed to and eluted from the surface of recombinant E. coli cells that express individual L. pneumophila antigens on their surface. These affinity-purified antibodies were then used to probe protein immunoblots prepared from the test strains to detect cross-reactive domains. We found that antigenic proteins are generally conserved in all L. pneumophila serogroups. Although some of these antigenic domains are shared with members of other Legionella species, they are associated with proteins of different molecular mass. Our approach to the study of antigenic cross-reactivity has potential advantages over similar studies that use either monoclonal antibodies or monospecific antibodies prepared by immunization with purified antigens.

Animals↗
PubMed1985

Identification of protein antigens of Legionella pneumophila serogroup 1.

Growth of Legionella pneumophila serogroup 1 in yeast extract broth was standardized, and protein profiles of detergent-solubilized cells were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Over 30 protein bands were identified, 6 of which were more prominent both in Coomassie brilliant blue-stained profiles and in fluorograms with intrinsically radiolabeled bacteria. These major proteins were 22,000 dalton (22K), 24K, 43K, 63K, 76K, and 78K. We found that the 24K and 63K major proteins were antigenic, as demonstrated both by radioimmunoprecipitation (RIP) of [35S]methionine-labeled organisms and by immunoblotting with rabbit hyperimmune sera. In addition, both techniques detected antigens migrating at 58K, 72K, 76K, and 78K. The major 22K and 43K major proteins and antigens migrating at 25.5K, 29K, and 46K were only detected by radioimmunoprecipitation, whereas antigens of 19K, 48K, 53K, and 68K were detected only by immunoblotting. Cell-surface localization of the proteins was determined by a modified radioimmunoprecipitation assay designed to react specifically with surface antigens and by the use of hyperimmune sera that had been extensively preabsorbed with intact cells to deplete the sera of antibodies directed against surface components. The 22K, 24K, 43K, 63K, and 78K major proteins and several minor proteins were found to be located on the surface of L. pneumophila cells.

Animals↗
PubMed1984

Legionella pneumophila surface antigens cloned and expressed in Escherichia coli are translocated to the host cell surface and interact with specific anti-Legionella antibodies.

Escherichia coli clones that express Legionella pneumophila antigens were isolated from a plasmid genomic library, and their antigens were characterized by immunoblotting with rabbit anti-L. pneumophila sera. Because previous studies of L. pneumophila antigens by whole-cell radioimmunoprecipitation suggested that comigrating native antigens were surface localized, we conducted experiments to determine if the cloned antigens were surface expressed in E. coli. Aliquots of antisera were absorbed by intact cells of three representative antigen-producing E. coli clones, and surface-bound antibodies were acid eluted from the intact cells. Immunoblots made with selectively absorbed antisera and eluted antibodies confirmed that reactivity to the homologous cloned antigens could be specifically absorbed from the antisera and then eluted from the cells, demonstrating a surface (antibody-accessible) localization in the cloned state. Antibodies eluted from the surface of an E. coli clone that expressed a 19-kilodalton antigen reacted with the surface of L. pneumophila in a liquid-phase, whole-cell enzyme-linked immunosorbent assay. In addition, intact cells of this clone were used in an enzyme-linked immunosorbent assay to detect serum antibody. E. coli cells that express foreign antigens on their surfaces can be used to develop antigen-specific immunoassays and to affinity purify monospecific antibodies.

Animals↗
PubMed1984

Pathogenic Trichomonas vaginalis cytotoxicity to cell culture monolayers.

Exposure of monolayer cultures of human urogenital and vaginal (HeLa), human epithelial (HEp-2), normal baboon testicular (NBT), and monkey kidney (Vero) cells to live pathogenic Trichomonas vaginalis resulted in extensive disruption of monolayers. Trypan blue was taken up by all host cells released from cell monolayers, which indicated irreversible damage of these cell types by trichomonads. Time and dose related data on cytotoxicity kinetics were obtained using increasing ratios of parasites to cells. All cell types were most sensitive to trichomonads at a multiplicity of infection of one. Release of tritiated thymidine (3H-thymidine) of the deoxyribonucleic acid (DNA) of prelabelled host cells after incubation with T vaginalis corroborated that extensive cytotoxicity was caused by pathogenic trichomonads in man. Only living parasites were cytotoxic, and no trichomonal toxic products were implicated in disruption of the cell monolayer cultures. A pathogenic bovine trichomonad, Tritrichomonas foetus KV-1, produced half as much cell damage as did T vaginalis. Trichomonas tenax, a non-pathogenic member of the normal flora of the oral cavity in man, produced no measurable cytotoxicity to HeLa cells when compared with the pathogenic human trichomonads.

Animals↗
PubMed1983

Binding of Leishmania promastigotes to macrophages.

Leishmania tropica promastigotes are easily attached to and engulfed by C3H peritoneal macrophages in vitro at 37 degrees C. Different sugars at 0.3-0.5 M inhibited in vitro the attachment of L. tropica promastigotes to C3H peritoneal macrophages with lactose (Gal-beta [1 leads to 4]Glc) being the most efficient. Inhibition of attachment is also affected by pre-treatment of promastigotes with galactose oxidase. Oligosaccharides extending from promastigote and amastigote cell surfaces contain an important proportion of non-reducing galactose as does the carbohydrate-rich factor (EF) excreted by promastigotes of L. tropica and L. donovani. This study suggests that Leishmania, an obligatory intracellular parasite, uses as a means of entering the host cell a cellular mechanism similar to that used in the removal of damaged cells from blood circulation. This mechanism is assumed to take advantage of the exposed sugars, particularly the exposed non-reducing galactose, on the parasite surface during the stage of attachment. Once the parasite is inside the cell, the EF it produces might have a protective function, being inhibitory to some of the host cell lysosomal enzymes.

Agglutination↗
PubMed1983

Chemotherapeutic activity of rifampicin on leishmanial amastigotes and promastigotes in vitro.

Rifampicin reduced the in vitro growth of Leishmania tropica major promastigotes and amastigotes: 100 micrograms/ml reducing the growth of amastigotes on Day 2 and 250 to 500 micrograms/ml reducing the growth of promastigotes on Day 1. A distinct effect of solvents was noted. Methanol, dimethylsulfoxide and Tween 80 appeared to increase drug effectiveness. Pretreatment of L. tropica major promastigotes with 200 micrograms/ml rifampicin for 3 days had no effect on either macrophage engulfment of the treated promastigotes or their transformation into amastigotes. Intracellular amastigotes treated for only 3 days recovered and 8-day treatment with 100 micrograms/ml rifampicin was insufficient to totally eliminate the amastigotes. The promastigotes of different strains of Leishmania showed different sensitivities to rifampicin, L. aethiopica being more sensitive than L. donovani, L. tropica minor and L. tropica major.

Dimethyl Sulfoxide↗