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Results for “antigen expression and secretion”

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PubMed2006

Characterization of Bacillus anthracis-like bacteria isolated from wild great apes from Cote d'Ivoire and Cameroon.

We present the microbiological and molecular characterization of bacteria isolated from four chimpanzees and one gorilla thought to have died of an anthrax-like disease in Côte d'Ivoire and Cameroon. These isolates differed significantly from classic Bacillus anthracis by the following criteria: motility, resistance to the gamma phage, and, for isolates from Cameroon, resistance to penicillin G. A capsule was expressed not only after induction by CO(2) and bicarbonate but also under normal growth conditions. Subcultivation resulted in beta-hemolytic activity and gamma phage susceptibility in some subclones, suggesting differences in gene regulation compared to classic B. anthracis. The isolates from Côte d'Ivoire and Cameroon showed slight differences in their biochemical characteristics and MICs of different antibiotics but were identical in all molecular features and sequences analyzed. PCR and Southern blot analyses confirmed the presence of both the toxin and the capsule plasmid, with sizes corresponding to the B. anthracis virulence plasmids pXO1 and pXO2. Protective antigen was expressed and secreted into the culture supernatant. The isolates possessed variants of the Ba813 marker and the SG-749 fragment differing from that of classic B. anthracis strains. Multilocus sequence typing revealed a close relationship of our atypical isolates with both classic B. anthracis strains and two uncommonly virulent Bacillus cereus and Bacillus thuringiensis isolates. We propose that the newly discovered atypical B. anthracis strains share a common ancestor with classic B. anthracis or that they emerged recently by transfer of the B. anthracis plasmids to a strain of the B. cereus group.

Alleles↗

PubMed1989

Immunological studies on patients with optic neuritis without evidence of multiple sclerosis.

We studied 6 patients with idiopathic optic neuritis (ON) after a mean follow-up period of 12 years. No evidence of multiple sclerosis (MS) was found on clinical grounds, nor by magnetic resonance imaging (MRI) or evoked responses. Levels of spontaneous proliferation, serum gamma-interferon (IFN-gamma) and lymphocyte MHC locus II antigen were similar in ON and in 6 patients with progressive MS, but different in healthy controls. This suggests that similar immunological conditions in vivo prevail after an idiopathic ON and in MS. A normal PHA-induced interleukin-2 receptor expression and lymphocyte proliferation but a low IFN-gamma secretion and MHC locus II antigen expression were observed. This suggests that an ON and MS defect is expressed after an interleukin-2 receptor ligand but before IFN-gamma secretion. Our findings also suggest that immunological factors do not explain the neuropathological confinement of the lesions in ON but the protective influence may rather be exerted by some as yet undefined genetic influence or may be explained by the different etiology of ON and MS.

Adult↗

PubMed1990

Is a function of the secreted hepatitis B e antigen to induce immunologic tolerance in utero?

Infants born to hepatitis B virus carrier mothers, who express a secreted form of the nucleocapsid antigen designated HBeAg, invariably become persistently infected. To investigate the role of immunologic tolerance mechanisms in chronic infection of the newborn, we have generated HBeAg-expressing transgenic mice. HBeAg-expressing transgenic mice were tolerant to both HBeAg and the nonsecreted nucleocapsid (hepatitis B cor antigen/HBcAg) at the T-cell level. Transgenic mice did not produce antibody to HBeAg but did produce anti-HBc antibody in vivo and in vitro. The coexistence of tolerance to HBc/HBe T-cell determinants and anti-HBc antibody production in vivo parallels the immunologic status of neonates born to carrier mothers. It was also demonstrated that the maintenance of T-cell tolerance to HBcAg/HBeAg required the continued presence of the tolerogen and in its absence persisted for less than 16 weeks. The reversibility of T-cell tolerance to HBcAg/HBeAg may explain the inverse correlation between age of infection and rates of viral persistence. These observations suggest that a function of the HBeAg may be to induce immunologic tolerance in utero. Expression of HBeAg may represent a viral strategy to guarantee persistence after perinatal infection.

Animals↗

PubMed2006

The 6-kilodalton early secreted antigenic target-responsive, asymptomatic contacts of tuberculosis patients express elevated levels of interleukin-4 and reduced levels of gamma interferon.

It is well known that the majority of healthy individuals exposed to Mycobacterium tuberculosis do not become clinically ill. We have previously shown that in recently exposed healthy contacts of tuberculosis (TB) patients, a strong immune response to the M. tuberculosis 6-kDa early secreted antigenic target (ESAT-6) virulence factor correlated with a higher risk of subsequent disease, although the mechanism was unclear at that time. Inspired by recent reports that elevated expression of interleukin-4 (IL-4) in health care workers exposed to M. tuberculosis also correlated with a higher risk of their subsequently developing disease, we examined expression of IL-4, its competitive antagonist IL-4delta2, and gamma interferon (IFN-gamma) in healthy household contacts of TB patients from Ethiopia. We then compared cytokine expression to their recognition of ESAT-6 (which is largely restricted to members of the tuberculosis complex and which serves as a reliable marker of infection) or to Ag85A (an antigen that is conserved among the mycobacteria and serves as a nonspecific control). Our study shows that in these recently exposed individuals, there is a correlation between a strong response to ESAT-6 and elevated expression of IL-4. Further, elevated expression of IL-4 is associated with lower expression of its antagonistic splice variant IL-4delta2 and with the Th1 cytokine IFN-gamma, suggesting that in these at-risk individuals, immunity is skewed away from a protective Th1 response, even before the development of clinical symptoms.

Antigens, Bacterial↗

PubMed1993

The antitumor immune response as a problem of self-nonself discrimination: implications for immunotherapy.

Much evidence now exists that tumors possess specific antigens recognizable by T cells. The goal of immunotherapy is to break tolerance to these antigens while preserving self-tolerance. Recently, newer approaches have been developed in animal systems that modify tumor cells genetically so that they express new antigens or secrete certain cytokines. Engineering tumor cells to secrete cytokines in a paracrine fashion can induce powerful local cytokine effects which, in addition to inducing local inflammation, can alter the presentation of tumor antigens or the activation of tumor-antigen-specific T lymphocytes, resulting in systemic antitumor immunity.

Animals↗

PubMed2006

Screen-less expanded bed column: new approach for the recovery and purification of a malaria transmission blocking vaccine candidate from Pichia pastoris.

An experimental malaria transmission blocking vaccine antigen, Pfs25H, expressed and secreted from Pichia pastoris was recovered and purified using a screenless expanded bed column equipped with a rotating fluid distribution system. This column was able to accommodate feed stock, containing 30% biomass, at a flow rate of 300-400 cm/h without affecting column stability. This capability is three times higher than the capability of the expanded bed column currently in use, which is equipped with a perforated plate fluid distribution system; this design could accommodate biomass concentrations of only up to 10%. The screen-less design did not affect the binding capacity, purification level or process yield and, therefore, shorten the process. Purified Pfs25H of 6.4 g were recovered from 37 l of Pichia pastoris culture in one step.

Cell Culture Techniques↗

PubMed1992

New strategies for active immunotherapy with genetically engineered tumor cells.

While previous tumor vaccine strategies have shown intriguing results, clearcut efficacy has been difficult to establish in human trials. Recently, newer approaches have been developed in animal systems that modify tumor cells genetically so that they express new antigens or secrete certain cytokines. Engineering tumor cells to secrete cytokines in a paracrine fashion can induce powerful local cytokine effects without producing significant systemic toxicity. In addition to local inflammation, this approach can alter the presentation of tumor antigen or activation of tumor antigen-specific T lymphocytes, resulting in systemic antitumor immunity.

Genes, MHC Class II↗

PubMed1996

Psychological and physical factors involved in chronic idiopathic prostatitis.

Idiopathic prostatitis is a common, often chronic condition in which psychological factors are suspected to play a role. Men with chronic prostatitis (n = 51) and a control group of 34 men without any chronic pain condition, equivalent on demographic characteristics, were compared on psychological and perineal muscle tension measures. Prostate-specific antigen and expressed prostatic secretion cell counts were also measured. Chronic prostatitis patients were consistently more elevated than controls on hypochondriasis, depression, and hysteria (MMPI), and on somaticization and depression (Brief Symptom Inventory), and were less elevated on masculine/instrumentality (Personal Attributes Questionnaire) scales. A cluster analysis of MMPI profiles revealed that 57% of the chronic prostatitis patients produced generally unelevated MMPI profiles, whereas the remaining 43% fell into two groups with distinct patterns of distress. The results indicate depression and psychosocial distress are common among chronic prostatitis patients, calling for careful evaluation and attention to psychological symptoms.

Adolescent↗

PubMed2006

Early clinical trials with a new tuberculosis vaccine, MVA85A, in tuberculosis-endemic countries: issues in study design.

Tuberculosis remains a substantial global health problem despite effective drug treatments. The efficacy of BCG, the only available vaccine, is variable, especially in tuberculosis-endemic regions. Recent advances in the development of new vaccines against tuberculosis mean that the first of these are now entering into early clinical trials. A recombinant modified vaccinia virus Ankara expressing a major secreted antigen from Mycobacterium tuberculosis, antigen 85A, was the first new tuberculosis vaccine to enter into clinical trials in September 2002. This vaccine is known as MVA85A. In a series of phase I clinical trials in the UK, MVA85A had an excellent safety profile and was highly immunogenic. MVA85A was subsequently evaluated in a series of phase I trials in The Gambia, a tuberculosis-endemic area in west Africa. This vaccine is the only new subunit tuberculosis vaccine to enter into clinical trials in Africa to date. Here, we discuss some of the issues that were considered in the protocol design of these studies including recruitment, inclusion and exclusion criteria, reimbursement of study participants, and HIV testing. These issues are highly relevant to early clinical trials with all new tuberculosis vaccines in the developing world.

Acyltransferases↗

PubMed2004

Cytokine profile in children during the first 3 months after the diagnosis of type 1 diabetes.

Type 1 diabetes is an autoimmune disease with an inflammatory process directed against the beta cells in pancreas. This investigation aimed at studying the immune response during the first 3 months after the diagnosis of type 1 diabetes, with focus on the balance of T-helper 1 (Th1)- and Th2-like cytokines, produced spontaneously and in response to relevant autoantigens. Peripheral blood mononuclear cells (PBMCs) were collected from type 1 diabetic children (10-17 years) at 5, 20, 35 and 90 days after diagnosis. Expression of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) mRNA were detected by real-time reverse transcriptase polymerase chain reaction and IFN-gamma, IL-10 and IL-13 by enzyme-linked immunosorbent assay in cell supernatant after stimulation with a glutamic acid decarboxylase 65 (GAD(65))-peptide [amino acid (a.a.) 247-279], insulin, the ABBOS-peptide (a.a. 152-169), phytohaemagglutinin and keyhole limpet haemocyanin. Spontaneous and antigen-induced expression and secretion of cytokines were low at the diagnosis of type 1 diabetes. During the first month, after diagnosis, the GAD(65)-peptide caused an increased ratio of IFN-gamma/IL-4 mRNA expression (P < 0.05) and increased secretion of IFN-gamma (P = 0.07). Expression of IFN-gamma mRNA did also increase from stimulation with insulin (P < 0.05), even though cytokine secretion remained low. Thus, duration after diagnosis as well as metabolic state should be carefully considered both in studies of the pathogenesis of type 1 diabetes and in immune intervention studies at onset.

Adolescent↗

PubMed2003

The making of a professional secretory cell: architectural and functional changes in the ER during B lymphocyte plasma cell differentiation.

B lymphocytes are small cells that express antigen receptors and secrete little if any IgM. Upon encounter with antigen, they differentiate into short-lived plasma cells, which secrete large amounts of polymeric IgM. Plasma cell differentiation entails a massive development of the endoplasmic reticulum to sustain high levels of Ig production. Recent findings suggest a role for the unfolded protein response in orchestrating the architectural and functional changes during terminal plasma cell differentiation.

Animals↗

PubMed1986

Cancer precursors and their control by BCG.

I am proposing a theory which states that stimulation of the immune system at birth detects and destroys embryonic cells or components thereof, including subcellular pattern defects, molecular structure defects and so forth which may be the source of malignancy not only in infancy but throughout life. The facts are that: Fetal rests or stigmata thereof remain in many of the organs of the body--the liver, the kidney, the spleen, the brain and so forth. These rests are usually absorbed by the end of the first year of life, but recent evidence indicates that stigmata of this fetal tissue may remain throughout one's entire life and be precursors of cancer. In animals and in humans, the antigens from malignant neoplasms crossreact with anti-fetal antibodies. Many tumors express fetal antigens and secrete fetal products. Alpha-feto-protein was found in adult cancer of the liver; carcino-embryonic antigen (CEA) has been reported in cancer of the colon-rectum; fetal alkaline phosphatase has been found in many adult cancers. Fetal tissue injected into animals will immunize these animals against certain transplanted tumors. Recently, in a lecture at Salk Institute, Sir Peter Medawar, Nobel Prize winner in medicine and until recently the head of the British Medical Research Council, described the use of quasi-fetal tissue as helpful in treating cancer of the adult. The infant's immune system is not fully developed. In fact, one can transfuse an infant without typing because he has built no antibodies to the blood types in early infancy. It has been shown in individuals of any age who are immune-deficient, either by heredity or acquired that the rate of malignancy may be as high as 10,000 times that of the general population. The immune system controls cancer development to a great extent. Published data suggests that the immune system detects and destroys embryonic cells or components thereof that may be a locus for cancer development. Our studies demonstrated that in some 85,353 BCG vaccinated newborns followed over a period of 20 years, there was an overall 74 percent reduction in the death rate from all forms of cancer when compared to a similar group not vaccinated. The differences were highly significant statistically. At an International Symposium, "BCG Vaccination Against Cancer and Leukemia" held in Chicago October 4-6, 1982, papers were presented from the U.S.A. (83), Austria (7), and Israel (54) which support the thesis of a lowering of mortality from cancer and leukemia in infants vaccinated at birth with BCG.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1991

Bacterial expression and secretion of various single-chain Fv genes encoding proteins specific for a Salmonella serotype B O-antigen.

Active single-chain Fv molecules encoded by synthetic genes have been expressed and secreted to the periplasm of Escherichia coli using the ompA secretory signal. Four different constructs were developed to investigate the effects of peptide linker design and VL-VH orientation on expression, secretion, and binding to a Salmonella O-polysaccharide antigen. Peptide linker sequences derived from the elbow regions of the Fab molecule were used alone or in combination with the flexible (GGGGS)2 sequence. VL and VH domain order in the single chain molecules had a profound effect on the level of secretion but hardly influenced total expression levels, which were approximately 50 mg/liter, chiefly in the form of inclusion bodies. With VL in the NH2-terminal position, the amount of secreted product obtained was 2.4 mg/liter, but when VH occupied this position the yield was less than 5% of this value. Enzyme immunoassays of the four products showed domain order and linker sequence affected antigen binding by less than an order of magnitude. Attempts to express active Fv from dicistronic DNA were unsuccessful, but active Fv was obtained from single-chain Fv by enzymic cleavage at a site in the elbow linker peptide. The thermodynamic binding parameters of intact and cleaved single-chain Fvs determined by titration microcalorimetry were similar to those of bacterially produced Fab and mouse IgG.

Amino Acid Sequence↗

PubMed1987

The effect of granulocyte factor (GF) on the production of interleukins and Tac antigen expression.

In the course of adherence granulocytes secrete the granulocyte factor (GF) which modifies lymphocyte functions in vitro. GF augments the interleukins production and diminishes mitogen induced Tac antigen expression in vitro, which may result in diminished IL-2 utilization. Consequently, such cells probably do not absorb IL-2 and do not exert their "inhibitory" potency measured in two step culture. The presented data show a relative deficit in interleukin generation in RA patients and have suggested the role of granulocytes in immunoregulation presumably in the course of diseases accompanied by inflammatory processes.

Adult↗

PubMed1987

Cell-type dependent expression and secretion of hepatitis B virus pre-S1 surface antigen.

The human hepatoma cell PLC/PRF/5 contains cloned genomes of hepatitis B virus, one of which was transfected to mouse cells (LTK-) or to human carcinoma cells (HeLa). Expression of the viral surface proteins was measured using monoclonal antibodies. The large protein with the pre-S1 domain was best expressed in HeLa cells and least in LTK- cells. In vivo growth of parental hepatoma cells or transfected HeLa cells increased expression of large, and decreased expression of small protein. Secretion of large protein required an excess of small protein. The secreted HBsAg from transfected HeLa cells contained filaments. Since the virus contains a defined proportion of all three proteins, a special regulatory situation is necessary for maturation of its envelope and its secretion in vivo.

Animals↗

PubMed1991

Induction of plasmacytomas secreting antigen-specific monoclonal antibodies with a retrovirus expressing v-abl and c-myc.

ABL-MYC, a recombinant murine retrovirus that expresses v-abl and c-myc, rapidly induces transplantable mono- or oligoclonal plasmacytomas in BALB/c mice. To determine if the targets for transformation of this retrovirus are antigen-committed B lymphocytes and to explore this system as an alternative technique for producing antigen-specific monoclonal antibodies, plasmacytomas were induced in mice that had been immunized with two different types of immunogens, hen egg white lysozyme and sheep red blood cells. The majority of these plasmacytomas secreted immunogen-specific antibodies. Plasmacytomas induced in unimmunized mice did not react with hen egg white lysozyme or sheep red blood cells. The specific antibodies were comparable in concentration, specificity, and affinity to monoclonal antibodies obtained with conventional hybridoma technology, but, in addition to IgGs and IgMs, they included specific IgA antibodies, which are rare among splenic-derived hybridomas. Our results demonstrate that a principal target for ABL-MYC is an antigen-committed B lymphocyte. In addition this procedure provides an alternative method for the production of monoclonal antibodies, without a requirement for hetero-caryon formation by cell fusion techniques.

Animals↗

PubMed1995

T cell activation by antigens on human melanoma cells--co-stimulation by B7-1 is neither sufficient nor necessary to stimulate IL-2 secretion by melanoma-specific T cell clones in vitro.

B7-1 expression, induced by transfection in poorly immunogenic murine tumours, was shown to elicit a T cell-mediated rejection of these tumours and further active immunity against the non-transfected tumour. We therefore asked to what level similarly induced expression of B7 on human melanoma cells would affect the antigen-dependent responses of tumour-specific T cell clones in vitro. Data presented show that B7-1 expression by melanoma lines: (i) significantly induced, or improved, an IL-2-dependent proliferative response of such clones to the antigen; (ii) increased the amount of IL-2 produced by two clones in response to the parental non-transfected tumour cells; and (iii) increased the TNF responses of all the CD4+ clones. However, despite these clear co-stimulatory effects on antigen-induced responses of all T cell clones, which demonstrated an effective interaction of the B7-1 transfected molecule with one or the other of its counter-receptors expressed on T cell clones, B7 co-stimulation did not correct the defect of IL-2 secretion exhibited by many of these clones in response to in vitro antigen presentation by melanoma cells. We further show that defective IL-2 secretion in response to melanoma antigens was not due to a T cell clone refractoriness induced by the culture, since one of these clones could be induced to secrete IL-2 by an antigen-expressing melanoma line, upon increased lymphocyte function associated antigen-3 expression induced by gene transfection. Together these data suggest that defective IL-2 secretion by many tumour-infiltrating lymphocytes clones in response to antigen presentation by melanoma cells in vitro is not exclusively due to the inability of these cells to provide an appropriate co-stimulation through the B7-1 molecule.

Animals↗

PubMed2002

Nonsecreted bacterial proteins induce recall CD8 T cell responses but do not serve as protective antigens.

Secreted or nonsecreted Ag expressed by recombinant Listeria monocytogenes can prime CD8 T cells. However, Ag-specific memory CD8 T cells confer protection against bacteria secreting Ag, but not against bacteria expressing the nonsecreted form of the same Ag. This dichotomy may be explained by a long-standing hypothesis that nonsecreted Ags are less effective than secreted Ags at inducing a protective immune response at the onset of infection. We tested this hypothesis by examining whether these two different forms of Ag induce different primary and secondary CD8 T cell responses. The primary responses to secreted and nonsecreted Ags expanded and contracted almost synchronously, although the responses to nonsecreted Ags were of lower magnitude. These results demonstrate that the kinetics of the CD8 T cell response are similar regardless of whether Ag is accessible to the endogenous MHC class I pathway or can only be presented through cross-presentation. No differences were detected in the CD8 T cell recall response to L. monocytogenes expressing secreted or nonsecreted Ags. Nonsecreted Ags are as effective as secreted Ags at the induction of a rapid recall response by memory CD8 T cells. Thus, the inability of nonsecreted bacterial proteins to serve as protective Ags cannot be attributed to a defective CD8 T cell response.

Animals↗