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At least 145 records · Page 8Linked to original sources
PubMed2005

Systemic mobilization of antigen presenting cells, with a chimeric Flt-3 and G-CSF receptor agonist, during immunization of Macaca mulatta with HIV-1 antigens is insufficient to modulate immune responses or vaccine efficacy.

In order to improve the efficacy of current vaccine candidates against HIV/AIDS, we sought to strengthen the induction of immune responses via simultaneous in vivo mobilization of dendritic cells using a chimeric Flt-3 and G-CSF receptor agonists (ProGP). We investigated ProGP treatment in combination with two DNA immunizations encoding HIV-Env89.6, SIV-Gag proteins to increase the priming of immune responses. Administration of this Flt-3/G-CSF chimera elicited marked increases in numbers of both plasmacytoid and myeloid dendritic cells. However, there was no increase seen in T-cell responses either directly following the DNA immunization or after further boosting with MVA vectors expressing HIV-Env89.6p, SIV-Gag. After challenge with SHIV89.6p all animals became infected and no differences were seen between the ProGP treated versus the control group with regard to plasma virus load or CD4 T-cell count. We conclude that besides mobilization of dendritic cells additional stimuli to induce dendritic cell maturation may be needed for avid boosting of antigen specific immune activation.

AIDS Vaccines↗
PubMed1999

Cytokine molecular adjuvants modulate immune responses induced by DNA vaccine constructs for HIV-1 and SIV.

DNA or nucleic acid immunization has been shown to induce both antigen-specific cellular and humoral immune responses in vivo. Moreover, immune responses induced by DNA immunization can be enhanced and modulated by the use of molecular adjuvants. To further engineer the immune response in vivo, we investigated the induction and regulation of immune responses from the codelivery of Thl cytokines (interleukin-2 [IL-2] and IL-12), Th2 cytokines (IL-4 and IL-10), and granulocyte-macrophage colony-stimulating factor (GM-CSF) genes along with a DNA vaccine construct encoding for simian immunodeficiency virus (SIV) gag/pol proteins. We observed that coinjection with IL-2, IL-4, IL-10, and GM-CSF resulted in increased levels of antigen-specific antibodies. In addition, we found that coinjection with cytokine genes drove the immune responses toward a more Thl or Th2 phenotype. We also observed that coadministration of IL-2, IL-12, and GM-CSF genes resulted in a dramatic enhancement of Th proliferation responses. Moreover, coimmunization with IL-12 genes resulted in a dramatic enhancement of antigen-specific cytotoxic T lymphocyte (CTL) responses. These results support the potential utility of molecular adjuvants in DNA vaccine regimens.

Adjuvants, Immunologic↗
PubMed1991

Enkephalinase-inhibitors modulate immune responses.

Exogenous opioid peptides, and enkephalins in particular, modulate a variety of immune performances in vivo and in vitro. In this study, the immunomodulatory role of endogenous opioids was investigated by means of central and peripheral administration of four peptidase inhibitors in the rat. Animals sensitized with sheep red blood cells (SRBC) were daily treated intraperitoneally (i.p.) with 0.2 mg/kg or 1 mg/kg of each inhibitor, or intracerebroventricularly (i.c.v.) with 0.02 mg/kg and 0.2 mg/kg of bestatin, des-tyrosine-methionine-enkephalin, (Des-Tyr1)Met-Enk; and actinonin, and 0.005 and 0.5 mg/kg of N-Carboxymethyl-phenilalanine-leucine,(N-C)Phe-Leu. Controls were injected i.p. and i.c.v. with saline. The results revealed that in animals treated i.p. with 0.2 mg/kg of bestatin and (N-C)Phe-Leu potentiated the plaque-forming cell (PFC) response and hemagglutinin production. In contrast, these immune responses were suppressed by 1 mg/kg. On the other hand, i.p. doses of 0.2 and 1 mg/kg of actinonin and (Des-Tyr1)Met-Enk potentiated humoral immune responses. When given i.c.v., all of the inhibitors used exerted clear dose-dependent immunomodulatory effects, i.e. increase in the PFC response and hemagglutinin production when given at lower doses (0.005-0.02 mg/kg), and decrease when injected with higher doses (0.2-0.5 mg/kg). These effects of enkephalin-related peptidase inhibitors, applied i.p. and i.c.v., suggest the involvement of endogenous enkephalins in immune mechanisms.

Adjuvants, Immunologic↗
PubMed1990

Immunity to sexual stages of human malaria parasites: immune modulation during natural infections, antigenic determinants, and the induction of transmission-blocking immunity.

Four antigens of Plasmodium falciparum have so far been identified as targets of transmission-blocking antibodies; three of them (Pfs 230, 48/45) are detectable in gametocytes and expressed on gametes, the fourth (Pfs 25) appears only after fertilization. Epitope analyses of each antigen were made with competitive immunoassays, and the extent of antigenic diversity determined amongst numerous isolates of P. falciparum. There was minimal variation within one of the two epitopes on Pfs 230 both of which induce transmission-blocking antibodies. The epitopes on Pfs 25 to which blocking monoclonal antibodies respond showed a variability amongst different isolates by immunofluorescence which was unexpected in view of sequence data on the molecule. Five epitope regions have been identified on Pfs 48/45 and antibodies to them interact in a complex manner. Antigenic diversity affecting these epitopes was minimal. In P. vivax malaria much greater polymorphism was seen amongst gamete surface antigens. Natural P. falciparum infections induce antibody responses to gametocyte/gamete surface antigens that will suppress infectivity to mosquitoes but these responses may involve reactivity with any of a series of different epitopes, interactions between antibodies, and may be sequential. In P. vivax infections antibody to the sexual stage antigens may suppress or enhance transmission depending on the antibody level. Cytokine production induced by sexual stage antigens may also modulate transmission, by rendering gametocytes non-infective. Experimental studies showed marked MHC-restriction of immune responses to gamete antigens (but not to the Pfs 25 zygote antigen); the evidence from studies in humans is less convincing. Antibody responses to the sexual stage antigens seem to be more frequent in persons who have experienced only one or a few attacks of malaria as opposed to those who have been exposed frequently. Some form of down-regulation may therefore be occurring.

Animals↗
PubMed2002

Immune modulation by ionizing radiation and its implications for cancer immunotherapy.

Ionizing radiation exhibits immunomodulatory properties, which could portend a future collaboration of cancer immunotherapy with radiation therapy. The danger model of immunity describes antigen-specific cellular immunity engendered by an inflammatory milieu. Dendritic cells (DCs) are attracted to this microenvironment, undergoing maturation after internalizing apoptotic and necrotic cellular debris. Mature DCs mediate antigen-specific cellular immunity via presentation of processed antigen to T cells. Administration of radiation has been utilized in vitro and in vivo to create an inflammatory setting, via induction of apoptosis, necrosis, cell surface molecules, and secretory molecules. Caspase-mediated cellular apoptosis is induced by radiation thro ugh multiple signaling pathways. Radiation upregulates expression of immunomodulatory surface molecules (MHC, costimulatory molecules, adhesion molecules, death receptors, heat shock proteins) and secretory molecules (cytokines, inflammatory mediators) in tumor, stromal, and vascular endothelial cells. Results of animal studies indicate possible radiation-mediated modulation of tumor antigen-specific immunity. Experimental data could indicate that the radiation-induced danger microenvironment engenders a DC-mediated antigen-specific immune response. Further enhancement of radiation-mediated inflammation and cell death can be achieved via administration of radiosensitizing pharmaceuticals. Radiation-mediated immune modulation currently remains unquantified and poorly understood. A major research effort will be required to elucidate mechanisms of action. With a thorough understanding of this phenomenon, we believe that ionizing radiation could be optimized for use with cancer vaccines and generate tumor antigen-specific cellular immunity.

Animals↗
PubMed1991

Immune modulation and cancer.

The concept that the immune system is involved in defence against cancer goes back nearly a hundred years. Despite increased sophistication in our analysis of the immune response it has proven difficult to demonstrate a powerful role of the immune system in either the prevention or treatment of cancer. Animal data has consistently and clearly shown that the immune system can identify and reject experimental tumours. In patients the data is more conflicting. The isolation of individual cytokines which stimulate specific components of the immune response and have a anti-cancer effect does suggest, however, that as we learn more about the interaction between immunity and cancer, novel methods for the diagnosis and therapy of cancer will be developed.

Antigens, Neoplasm↗
PubMedDate not supplied

Immune modulation and disease patterns in population groups.

A hypothesis which explains disease prevalence among different socio-economic groups following early infantile modulation of cell-mediated immunity by infection and nutrition related stress is presented. Wealthy populations living under highly hygienic circumstances can develop their cell-mediated immunity to genetic expectation while their humoral systems remains unstimulated. Primitive populations protect the infant's immune development by breast feeding and suffer from temporary cell-mediated immune deficiencies due to intercurrent infectious disease and famine later on. Intermediary populations harbour a small percentage of people, whose cell-mediated immune system has been permanently damaged by infection in early childhood, leading to a high incidence of diseases linked to cell-mediated immune deficiency. The possible cocarcinogenesis of the cell-mediated immune deficiency following repeated gastroenteritis and persistent stimulation of B cells, leading to alpha heavy chain disease and primary intestinal lymphoma, or due to falciparum malaria in newborns and its impact on the EB virus genome in development of Burkitt's lymphoma, are discussed.

Africa↗
PubMed2005

Neutrophils mediate immune modulation of dendritic cells through glycosylation-dependent interactions between Mac-1 and DC-SIGN.

Neutrophils are key players of the innate immune system that provide a first line of defense against invading pathogens. However, it is unknown whether neutrophils can interact with dendritic cells (DCs) to modulate adaptive immune responses. We demonstrate that neutrophils strongly cluster with immature DCs and that activated, not resting, neutrophils induce maturation of DCs that enables these DCs to trigger strong T cell proliferation and T helper type 1 polarization of T cells. This neutrophil-DC interaction is driven by the binding of the DC-specific, C-type lectin DC-SIGN to the beta(2)-integrin Mac-1. Strikingly, DC-SIGN only interacts with Mac-1 from neutrophils, but not from other leukocytes, mainly because of specific Lewis(x) carbohydrates that are present on the alpha(M) chain of Mac-1 from neutrophils. Furthermore, we show that besides the formation of cellular contact, the tumor necrosis factor-alpha produced by activated neutrophils is essential for inducing DC maturation. Our data demonstrate that DC-SIGN and Mac-1 define a molecular pathway to establish cellular adhesion between DCs and neutrophils, thereby providing a novel cellular link between innate and adaptive immunity.

Cell Adhesion↗
PubMed2006

Single dose vaccine based on biodegradable polyanhydride microspheres can modulate immune response mechanism.

This study focuses on the development of single dose vaccines based on biodegradable polyanhydride microspheres that have the unique capability to modulate the immune response mechanism. The polymer system employed consists of copolymers of 1,6-bis(p-carboxyphenoxy)hexane and sebacic acid. Two copolymer formulations that have been shown to provide extended release kinetics and protein stability were investigated. Using tetanus toxoid (TT) as a model antigen, in vivo studies in C3H/HeOuJ mice demonstrated that the encapsulation procedure preserves the immunogenicity of the TT. The polymer itself exhibited an adjuvant effect, enhancing the immune response to a small dose of TT. The microspheres provided a prolonged exposure to TT sufficient to induce both a primary and a secondary immune response (i.e., high antibody titers) with high-avidity antibody production, without requiring an additional administration. Antigen-specific proliferation 28 weeks after a single immunization indicated that immunization with the polyanhydride microspheres generated long-lived memory cells and plasma cells (antibody-secreting B cells) that generally do not occur without maturation signals from T helper cells. Furthermore, by altering the vaccine formulation, the overall strength of the T helper type 2 immune response was selectively diminished, resulting in a balanced immune response, without reducing the overall titer. This result is striking, considering free TT induces a T helper type 2 immune response, and has important implications for developing vaccines to intracellular pathogens. The ability to selectively tune the immune response without the administration of additional cytokines or noxious adjuvants is a unique feature of this delivery vehicle that may make it an excellent candidate for vaccine development.

Animals↗
PubMed2000

Interleukin-18 modulates immune responses induced by HIV-1 Nef DNA prime/protein boost vaccine.

Many different HIV-1 vaccine strategies have been developed, but as yet none has been completely successful. Promising results from combined DNA prime/protein boost vaccines have been reported. Specific immune responses generated by DNA vaccines can be modulated by the co-delivery of genes coding for cytokines. In this study, we have used the intradermal route by needle injection of a plasmid coding for the HIV-1 Nef accessory protein. We show that DNA prime/protein boost vaccine combinations increase the humoral and cellular immune responses against HIV-1 Nef and that the co-injection of DNA encoding Interleukin-18 (IL-18) modulates the specific immune response towards a Th1 type.

AIDS Vaccines↗
PubMed1996

Immune response & modulation of immune response induced in the guinea-pigs by Mycobacterium avium complex (MAC) & M. fortuitum complex isolates from different sources in the south Indian BCG trial area.

A total of 139 guineapigs were used to study the immune response and its modulation induced by Mycobacterium avium complex (MAC) and M. fortuitum complex strains obtained from different sources in the south Indian BCG trial area. The guineapigs were divided into groups and some were directly sensitised/immunised with different MAC strains. M. fortuitum complex strain or BCG and others were sensitised with MAC or M. fortuitum complex and then immunised with BCG. The resulting delayed type hypersensitivity (DTH) response in the different groups of guineapigs was studied by skin tests using PPD-RT23 and PPD-B, and protective response was studied by challenging the guineapigs with a south Indian low virulent strain of M. tuberculosis and enumerating the bacilli in spleen at different points of time. The 3 strains of MAC induced similar low levels of DTH to PPD-RT23 but much higher and varying levels of DTH to PPD-B. MAC strains from soil and sputum induced different levels of immune modulation during subsequent immunisation with BCG on the DTH response to PPD-RT23 and PPD-B. At 2 wk after challenge, 23.8, 81 and 90.5 per cent protection was induced by the standard strain, soil isolate and sputum isolate of MAC, respectively, while 33.3 per cent protection was induced by the M. fortuitum complex strain compared to the protection induced by BCG alone. Prior exposure to MAC or M. fortuitum complex did not have any modulatory effect on the protective immunity due to BCG at this time point. However, at 6 wk after challenge, while the guineapigs immunised with BCG were protected, modulation of the protective response resulting from BCG was observed in the guineapigs sensitised with MAC and M. fortuitum from soil.

Animals↗
PubMed1992

Immune modulating effects of low doses of cyclophosphamide and keyhole limpet hemocyanin on peripheral blood immune parameters in patients with metastatic renal cell carcinoma.

Assessing the peripheral blood immune status, we had found evidence of immunosuppression in metastatic renal cell carcinoma. Since immunosuppression might interfere with the outcome of immunotherapy, it was submitted to further investigation. Immunosuppression can be mediated by T suppressor cells, which for their part are inhibited by low-dose cyclophosphamide (Cy). We tested whether the immunomodulating effects of the biological response modifier keyhole limpet hemocyanin (KLH) on cellular and humoral immune parameters would be intensified by low-dose Cy. 10 patients were given 300 mg/m2 Cy i.v. 3 days before application of 1 mg KLH i.m. up to 8 times in 4-weekly intervals. Immune parameters were assayed twice pre-therapeutically, and prior to and 1 day and 1 week after each KLH injection. In contrast to the results obtained with KLH-mono-application, lymphocyte subsets-with the exception of T4 cell counts and the T4/T8 ratio-remained stable during the first 4 months of observation. There were increases in immunoglobulins and in the immunoactivation markers tumor necrosis factor, neopterin and beta 2-microglobulin. The tendencies found here differed from those found in a previous study on patients who were given KLH alone, and were similar to those found in patients with nonmetastatic disease who received KLH alone. However, the increases of the activation markers during KLH+Cy application were at best half as much as in patients with nonmetastatic disease. In conclusion, immunosuppression was influenced, but not counterbalanced by low-dose Cy. Most probably other mediators of immunosuppression than T suppressor cells, for example prostaglandin E2, must be considered as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed2006

Immune modulation by mesenchymal stem cells.

Mesenchymal stem cells (MSCs) have been shown to suppress activation of T cells both in vivo and in vitro. In vivo, this may be a way for the body to maintain homeostasis and inhibit immune activation in distinct compartments, such as the bone marrow and the interface between mother and fetus. MSCs modulate the immune function of the major cell populations involved in alloantigen recognition and elimination, including antigen presenting cells, T cells, and natural killer cells. The molecular mechanism that mediates the immunosuppressive effect of MSCs is not completely understood.

Animals↗
PubMed1988

Opioid peptides modulate immune functions. A review.

In the past few years it has become evident that neuropeptides may be direct mediators in the modulation of the immune response and the unspecific defense by the brain. Lymphocytes have been thought to have opioid receptors and to respond to opioids with an increase in blastogenesis, cytotoxicity and factor release. Lymphocytes are said to release various neuropeptides. Furthermore, there are some unexplained effects of morphine on the immune system and of the immune system on morphine withdrawal. The purpose of this paper is to review what has been previously published in this field. The well established modulation of phagocyte functions by opioids will only be scanned.

Animals↗
PubMed1990

Immune modulation exerted by thymic humoral factor (THF-gamma 2), on T-cell subsets and IL-2 production of umbilical cord blood lymphocytes.

The effect of a synthetic thymic humoral factor, THF-gamma 2, on the immune competence of T-cells was investigated in vitro on lymphocytes from human cord blood (UCBL). It was found that preincubation of UCBL with THF-gamma 2 caused an increase in the percentage of cells expressing the CD4 or the CD8 differentiation antigens, but did not affect the percentage of CD3 cells. The effect of THF-gamma 2 on PHA-induced IL-2 secretion was also studied and found that a 3hr preincubation with THF-gamma 2, prior to suboptimal PHA stimulation caused an increase in the IL-2 activity of the treated UCBL cultures. This effect was THF-gamma 2 dose dependent with an optimum in the range of 300-600 ng/ml and was not influenced by irradiation of the UCBL. These results indicate that THF-gamma 2, a synthetic octapeptide, modulates the immune state and response of human umbilical cord blood lymphocytes.

Antigens, Differentiation, T-Lymphocyte↗
PubMed2026

Transcriptomic changes in the gut mucosa of fasting northern elephant seal pups reveal immune modulation during early microbiome establishment.

Fasting is an integral component of the life-history of many species. Following abrupt weaning, northern elephant seal pups (Mirounga angustirostris) undergo an extended post-weaning fast of approximately 60 days. During this period, enteric bacterial diversity increases, suggesting that host immune regulation may facilitate the establishment of microbial communities. However, the molecular processes occurring within the intestinal mucosa during this transition remain poorly understood. To investigate these mechanisms, we characterized transcriptional changes in the enteric mucosa of male and female northern elephant seal pups sampled at weaning and after one month of fasting. Total RNA isolated from rectal swabs was sequenced and aligned to the Mirounga angustirostris reference genome. Differential gene expression and gene set enrichment analyses were used to identify genes and pathways associated with fasting and sex-specific responses. Fasting was accompanied primarily by transcriptional downregulation, including genes involved in antimicrobial defense, inflammation, protein turnover, and epithelial remodeling. In contrast, several genes associated with B-cell activity and immune recognition were upregulated. Gene Set Enrichment Analysis revealed coordinated activation of immune-regulatory pathways indicating dynamic modulation of intestinal immunity rather than generalized immune suppression. Pronounced sex-specific differences were also observed. Male pups exhibited transcriptional patterns consistent with enhanced immune tolerance, whereas females showed broader immune-pathway activation, including enrichment of pro-inflammatory and stress-response pathways. Several non-coding RNAs also displayed sex-specific changes in expression. Together, these findings suggest that fasting induces transcriptional remodeling of the gut and may contribute to immune regulation during a critical period of microbiome establishment in northern elephant seal pups.

Animals↗
PubMed1993

Perioperative immune modulation.

BACKGROUND: The effects of operative trauma on systemic immunity were studied. The relative effects of skin incision and of breaching the peritoneum were determined. In addition, the role of the antiendotoxic agent taurolidine in preventing postoperative immune suppression was assessed. METHODS: Systemic immune responsiveness was measured as the delayed-type hypersensitivity (DTH) response to 2-4 dinitro l-fluorobenzene (DNFB) with an in vivo rat model. The effect of both laparotomy and taurolidine on the hepatic Kupffer cell population was determined by immunohistochemistry. RESULTS: This study confirmed that cellular immunity is significantly depressed after laparotomy (15.5%; range, 2.5%-24.0%) compared with unoperated controls (26.77%; range, 9.2%-38.0%). Opening the peritoneum appeared to be a critical factor in inducing this immunosuppression, in which animals undergoing a similar midline incision without opening of the peritoneum displayed minimal alteration in their DTH response (20.5%; range, 0.85%-41.5%). In addition, intraperitoneal administration of taurolidine in the perioperative period prevented this decrease in postoperative DTH response. Kupffer cell numbers were increased after intraperitoneal administration of taurolidine, compared with animals treated with intraperitoneal saline solution or unoperated controls. CONCLUSIONS: These findings confirm the presence of an operatively induced decrease in immune responsiveness and suggest that entering the peritoneum is an important factor in the induction of this effect. In addition, administration of taurolidine acts to prevent the impact of laparotomy on DTH response, possibly by preventing perioperative portal endotoxemia.

Animals↗