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S Tonkonogy

Publications and source records attributed to S Tonkonogy.

11 recordsLinked to original sources
PubMed1998

Resident enteric bacteria are necessary for development of spontaneous colitis and immune system activation in interleukin-10-deficient mice.

Mice with targeted deletion of the gene for interleukin-10 (IL-10) spontaneously develop enterocolitis when maintained in conventional conditions but develop only colitis when kept in specific-pathogen-free (SPF) environments. This study tested the hypothesis that enteric bacteria are necessary for the development of spontaneous colitis and immune system activation in IL-10-deficient mice. IL-10-deficient mice were maintained in either SPF conditions or germfree conditions or were populated with bacteria known to cause colitis in other rodent models. IL-10-deficient mice kept in SPF conditions developed colitis in all segments of the colon (cecum and proximal and distal colon). These mice exhibited immune system activation as evidenced by increased expression of CD44 on CD4(+) T cells; increased mesenteric lymph node cell numbers; and increased production of immunoglobulin A (IgA), IgG1, and IL-12 p40 from colon fragment cultures. Mice populated with bacterial strains, including Bacteroides vulgatus, known to induce colitis in other rodent models had minimal colitis. Germfree IL-10-deficient mice had no evidence of colitis or immune system activation. We conclude therefore that resident enteric bacteria are necessary for the development of spontaneous colitis and immune system activation in IL-10-deficient mice.

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PubMed1996

Interleukin 10 suppresses experimental chronic, granulomatous inflammation induced by bacterial cell wall polymers.

BACKGROUND AND AIMS: Interleukin 10 (IL10) inhibits monocyte/macrophage and T lymphocyte effector functions. This study examined the effect of systemically administered IL10 on acute and chronic granulomatous enterocolitis, hepatitis, and arthritis in a rat model. METHODS: Lewis rats were injected intramurally with streptococcal peptidoglycan-polysaccharide (PG-APS) polymers. Beginning 12 hours before PG-APS injection, rats were treated daily with subcutaneous murine recombinant IL10 or vehicle for three or 17 days. RESULTS: IL10 attenuated acute enterocolitis in a dose dependent fashion (p < 0.01). Protective effects were more profound in the chronic granulomatous phase with decreased enterocolitis and markedly inhibited leucocytosis, hepatic granulomas, and chronic erosive arthritis (p < 0.001). IL10 downregulated tissue IL1, IL6, tumour necrosis factor alpha, and interferon gamma gene expression, consistent with the in vitro effects of IL10 on PG-APS-stimulated splenocytes. Caecal IL1 protein concentrations and IL2 and interferon gamma secretion by in vitro stimulated mesenteric lymph nodes were downregulated in IL10 treated animals. CONCLUSIONS: These results indicate that exogenous IL10 can inhibit experimental granulomatous inflammatory responses and suggest that IL10 treatment could be an effective new therapeutic approach in human disorders such as Crohn's disease, rheumatoid arthritis, and sarcoidosis.

Actins↗
PubMed1995

A reverse transcription-polymerase chain reaction technique to detect feline cytokine genes.

The ability to detect feline cytokine expression would allow further characterization of the feline immune system. Bioassays are currently available for the measurement of feline IL2, IL6 and TNF alpha but not for other biologically important cytokines. To detect the expression of other cytokines, a reverse transcription-polymerase chain reaction (RT-PCR) procedure was developed. Since feline cytokine gene sequences other than TNF alpha were not available, mammalian DNA and mRNA sequences for IL2, IFN gamma, IL4, IL6, IL10, IL12 and beta-actin, obtained from the Genbank database were compared and oligonucleotide primers chosen from consensus sequences. To validate the cytokine and beta-actin primers, peripheral blood mononuclear cells from specific pathogen free (SPF) cats were cultured in the presence of Con A for various periods of time (0-72 h). RNA was collected, reverse transcribed into cDNA, and the cDNA was amplified by PCR with each set of cytokine primer pairs. RT-PCR products were hybridized with specific 32P end-labeled internal oligonucleotide probes and then analyzed with the AMBIS imaging system to determine the kinetics of cytokine mRNA production. The beta-actin signal was used to control for sample to sample variation in the quantity of mRNA and variation in the RT and PCR reactions. Peak mRNA expression for most cytokines was found to occur between 2 to 4 h of Con A stimulation. mRNA expression was correlated with cytokine bioactivity for IL2 and IL6. Peak IL2 bioactivity occurred after 8 h of Con A stimulation, 4 h after the mRNA expression had peaked. Although IL6 mRNA expression peaked between 2 and 4 h of stimulation, bioactivity was not detected until 8 h of stimulation and continued to increase over the next 24-48 h.

Animals↗
PubMed1995

Tumor necrosis factor-alpha responses are depressed and interleukin-6 responses unaltered in feline immunodeficiency virus infected cats.

Feline immunodeficiency virus (FIV), a lentivirus similar to HIV, causes an acquired immunodeficiency syndrome in cats. Similar to human immunodeficiency virus (HIV), the pathogenesis of FIV is associated with dysregulation of the cytokine network. While alterations in tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) expression have been reported in HIV-infected patients, changes attributable to HIV and those caused by cofactors such as secondary infections cannot always be readily distinguished. This study evaluated the effect of FIV infection on TNF-alpha and IL-6 production in cats not exposed to other potential cofactors such as secondary infections. TNF-alpha and IL-6 activities were evaluated in bronchoalveolar lavage (BAL) cells from FIV-infected and uninfected specific pathogen free (SPF) cats. Supernatants from lipopolysaccharide (LPS)-stimulated BAL cells from uninfected SPF cats had high levels of TNF-alpha and IL-6 activity, while stimulated BAL cell supernatants from FIV-infected SPF cats had significantly lower levels of TNF-alpha but unaltered IL-6 activity. Similarly, Con A/phorbol myristate acetate (PMA) stimulated non-adherent (NA-) peripheral blood mononuclear cells (PBMC) from FIV infected cats synthesized less TNF-alpha than similarly treated NA-PBMC from uninfected cats. Feline immunodeficiency virus could be recovered from the culture supernatants of BAL cells from infected cats by co-cultivation with susceptible lymphocytes. In situ hybridization identified FIV mRNA in a small fraction of alveolar macrophages in the BAL cell cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1991

Transforming growth factor-beta and IL-4 cause helper T cell precursors to develop into distinct effector helper cells that differ in lymphokine secretion pattern and cell surface phenotype.

We have investigated the effects of TGF-beta on the in vitro development of different subsets of Th cells and find that addition of TGF-beta results in the generation of cell populations with distinct characteristics that resemble those of memory cells. Resting, short-lived CD4+ precursor T cells can be induced by mitogen stimulation to proliferate and differentiate in in vitro cultures and after 4 to 7 days will generate a population of cells that, when restimulated, synthesize and secrete high titers of a wide variety of lymphokines. It has been previously reported that the presence of the lymphokine IL-4 during in vitro culture results in the generation of a population of "effector" cells that can be rapidly induced by mitogen to synthesize and secrete high titers of IL-4, IL-5, IL-3, IFN-gamma, and granulocyte-macrophage-CSF. We find that TGF-beta added to CD4+ precursors, suppresses the development of IL-4/IL-5 secreting effectors and results instead in the development of cells secreting IL-2 and IFN-gamma. CD4 T cells generated in the presence of TGF-beta show little or no expression of CD45RB, in contrast to those developed in IL-4 (or in IL-2 alone) that express high surface densities of CD45RB. The kinetics of cell recovery also differs when TGF-beta rather than IL-4 is present during culture. Cultures of effectors generated in TGF-beta, initially have low cell recoveries but cells expand dramatically between 4 to 7 days in the presence of IL-2 whereas IL-4 induces optimum cell recovery at day 4 and cell recoveries decrease with further culture. The properties of cells grown in TGF-beta thus show several attributes in common with memory or highly differentiated CD4+ cells, i.e., IL-2 as a predominant cytokine, easy propagation and low expression of CD45RB. Therefore, we propose the hypothesis that TGF-beta favors the development of a population(s) of Th cells that is likely to give rise to memory cells although IL-4 favors development of a short-lived effector population that secretes Th2 lymphokines.

Animals↗
PubMed1991

Characterization of antigen-specific CD4+ effector T cells in vivo: immunization results in a transient population of MEL-14-, CD45RB- helper cells that secretes interleukin 2 (IL-2), IL-3, IL-4, and interferon gamma.

In previous studies we demonstrated that, following activation by mitogens or alloantigens, helper T cell precursors proliferate and differentiate in vitro to produce a population of effector cells that secrete high titers of lymphokines upon restimulation. In this report, we demonstrate that a similar effector population develops in vivo following primary antigen stimulation. When restimulated with specific antigen in vitro, CD4+ T cells from mice primed 5 to 7 days previously by subcutaneous administration of keyhole limpet hemocyanin (KLH) in adjuvant, produced high levels of interleukin 2 (IL-2), IL-4, and IL-3, and little or no interferon gamma (IFN-gamma) or IL-5. The effector T cells provided excellent helper activity for in vitro antibody responses of 4-hydroxy-5-iodo-nitrophenyl acetic acid-primed B cells with the production principally of the immunoglobulin G1 (IgG1) and IgM isotypes, small quantities of IgG3, and no detectable IgG2a, or IgG2b. Antigen-specific secretion of IL-2, IL-3, and IL-4 by in vivo effectors was detectable by 12 hours following in vitro restimulation. IFN-gamma and IL-5 were not detected until 48 and 72 hours of culture, respectively, and low levels of these lymphokines were produced. Lymphokine production by primed CD4+ T cells could be induced as early as 3 days following immunization, peaked on day 5, and declined thereafter. The kinetics of in vivo appearance of effector CD4+ T cells that produce lymphokines upon restimulation in vitro were similar for each of the lymphokines examined. Mice depleted of precursor CD4+ T cells by adult thymectomy exhibited limited capacity to generate lymphokine secreting CD4+ T cells in response to primary immunization with KLH, suggesting that the majority of lymphokine producing T cells arise from short-lived and/or precursor cells. Separation of CD4+ T cells from KLH-primed mice on the basis of expression of the lymph node-specific homing receptor, MEL-14, revealed that antigen-specific production of IL-2, IL-3, IL-4, and IFN-gamma was exclusively associated with the MEL-14- subset of CD4+ T cells. Separation on the basis of CD45RB expression, demonstrated that antigen-specific lymphokine production was primarily associated with the minor CD45RB- population, which has been previously associated with memory activity. Our results indicate that primary in vivo immunization leads to the development of a transient population of helper-effectors with a unique phenotype that can produce large quantities of lymphokines and mediate excellent helper activity for B cells.(ABSTRACT TRUNCATED AT 400 WORDS)

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PubMed1991

Helper T-cell subsets: phenotype, function and the role of lymphokines in regulating their development.

We have concentrated here on the lymphokines which might serve to regulate the different pathways of precursor development. We suggest that, as a result of antigenic stimulation, specific precursor cells both proliferate and become committed to develop into either an effector cell, a memory cell or an anergized cell. Anergy has not been dealt with in this review, but it is likely to be one of the options available. The development of an effector population takes 4-7 d (quite analogous to the time it takes for CTLp to become CTL and for resting B to become Ab-forming cells). The effector populations are large, generally IL-2R-positive cells. These cells have upregulated many adhesion molecule systems [e.g., Pgp-1, LFA-1 and ICAM-1 (Swain unpublished)], but downregulated the Mel-14 homing receptor. Effectors are ready to respond to APC such as specific B cells with a rapid synthesis and secretion of lymphokines. The effector population is then quickly downregulated, both by the turn off of lymphokine synthesis/secretion and possibly by its own suicide. This kind of pattern makes teleological sense since the cells making such high titers of lymphokines could have many potent pleitropic effects. It also seems to be the strategy employed in the generation of other terminally differentiated effectors (such as CTL and plasma cells). The requirement for restimulation and the requirement for direct and perhaps prolonged contact between the helper effector and the APC-B cell can be expected to help ensure that these lymphokines are localized (reviewed in Swain & Dutton 1987, Swain & Croft 1990) and effectively delivered to specific responding cells. We postulate that at the same time, or perhaps subsequent to this, another set of signals drives precursors to generate prememory cells. Our studies suggest these emerging memory cells may be phenotypically unique and we postulate that they are specialized to become a "long-lived" population of memory cells that will persist indefinitely as a protective population of increased frequency for the antigen encountered and which is also able to respond more rapidly and effectively. The greater effectiveness of the memory response would thus be due to dramatically increased frequency, to characteristic and stable changes in adhesion molecule expression and to the fact that, in addition to IL-2, resting memory cells also secrete at least low titers of IL-3, IL-4, IFN-gamma and other lymphokines upon initial restimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1982

The Qa2 subregion controls the expression of two antigens recognized by H-2-unrestricted cytotoxic T cells.

B6.KI mice were immunized with spleen cells from B6.K2, a Qa2-subregion congenic strain. Cytotoxic T cells were generated that recognize two target antigens controlled by this region. One of the target antigens is Qa-2. This was demonstrated by the findings that pretreatment of target cells with monoclonal anti-Qa-2 antibody blocked lysis of target cells, and Qa-2 target antigens and serological determinants had a concordant distribution on a panel of B10.W (wild) mice. The gene controlling the Qa-2 target antigen is not polymorphic because B6.K2 and three strains of Qa-2(+) B10.W mice express the same antigens, as determined by a CTL cold target competition assay. Anti-Qa-2 CTL were H-2 unrestricted because effector cells lysed Qa-2(+) targets irrespective of their H-2 haplotype, including five B 10.W strains, and lysis was not inhibited by pretreating target cells with anti-H-2 sera. The Qa2 subregion does not act as a restricting locus for anti-minor-H antigen CTL. A second target antigen was detected that was associated with the expression of the Qa-5 determinant. However, CTL activity could not be blocked by pretreating target cells with monoclonal anti-Qa-5. Therefore, the CTL target antigen may be expressed on a Qa-5(-) molecule. Although the Qa-5 associated CTL specificity is only detected on H-2D(b) strains, it is unlikely that CTL recognition is H-2 restricted because anti-H-2(b) sera has no effect in blocking this reactivity. Qa-2 and H-2 class I antigens share a similar structure and serve as target antigens for unrestricted CTL. However, unlike class I H-2 genes, Qa-2 neither restricts antigen-specific CTL nor is polymorphie. Therefore, it is likely that Qa-2 and H-2 are derived from a common ancestral gene and have evolved to serve different functions.

Animals↗
PubMed1982

Qa-1 and Qa-2 expression on CFU-s.

Multipotential stem cells can be detected in bone marrow cells preparations by injecting these cells into syngeneic irradiated hosts. Colonies (CFU-s) are visible macroscopically on the spleen after 8 days. Pretreatment of A-Tlab (Qa-1.2) bone marrow with A-anti-A-Tlab serum (anti-Qa-1.2), in the presence of complement, reduced CFU-s by 80% whereas A-Tlab anti-A serum (anti-Qa-1.1) treatment had no effect. Pretreatment of A(Qa-1.1) bone marrow with A-Tlab anti-A serum reduced macroscopic splenic colonies by 78%. Similar results were obtained by using C57BL/6 (Qa-1.2) and B6-Tlaa (Qa-1.1) bone marrow. Thus, both Qa-1.1 and Qa-1.2 are expressed on CFU-s. Qa-2 expression on CFU-2 was examined in the same manner. B6.KI anti-B6 (anti-Qa-2,3) serum reduced CFU-s numbers by 87% on B6 (Qa-2,3+) while having little or no effect on B6.KI (Qa-2,3-). Treatment with D3.262, a monoclonal anti-Qa-2 antibody, reduced B6 CFU-s by 80%, and had no effect on B6.KI CFU-s. Detection of Qa-1 and Qa-2 on CFU-s underscores the wide distribution of the Qa antigens in the hematopoietic system.

Animals↗
PubMed1980

Monoclonal antibodies specific for kappa chain, lambda chain, and IgG1 of human gammaglobulin.

Hybrid cell lines secreting antibodies specific for human gammaglobulin (HGG) were prepared by cell fusion and cloning techniques. The monoclonal antibodies were tested for their antibody reacts with a different antigenic determinant of HGG. One reacts with isolated kappa (kappa) light chains, one with isolated lambda (lambda) light chains, and one with the Fc fragment of IgG1 molecules. The reactivity patterns of two additional monoclonal antibodies are more complex. One reacts with a determinant present on the Fc of all IgG subclasses and the other binds to a determinant on the Fab of IgG molecules. The two monoclonal antibodies reactive with light chains also bind to surface components of human B cells. The murine immunoglobulin (Ig) class of each clone product was identified.

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