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Biomedical subjects

A Cassone

Publications and source records attributed to A Cassone.

At least 55 records · Page 3Linked to original sources
PubMed1998

Cell-mediated immune response of healthy adults to Bordetella pertussis vaccine antigens.

Cell-mediated immunity (CMI) to Bordetella pertussis and acellular pertussis vaccine constituents (pertussis toxin, pertactin, and filamentous hemagglutinin) were studied in peripheral blood mononuclear cells (PBMC) and T cell cultures from healthy adults with no record of vaccination against, or history of, pertussis. Similarly to stimulation with common recall antigens, PBMC proliferation was induced in 80%-100% of the cultures, depending on the specific B. pertussis stimulant. Proliferation did not occur when antigen-presenting cells were ablated by chemical or physical methods or with naive cord blood lymphocytes. B. pertussis antigen stimulation resulted in a preferential induction of type 1 cytokine profile, as shown by interferon-gamma and interleukin-2 (but no interleukin-4 or interleukin-5) gene transcripts and actual cytokine production by T cells. The data suggest that most healthy adults are repeatedly exposed to B. pertussis, with natural acquisition of antigen-specific CMI and a putatively protective type 1 cytokine pattern.

Adhesins, Bacterial↗
PubMed1998

Prevalence of markers of exposure to Bordetella pertussis among Italian young adults.

Titers of serum antibody and cell-mediated immunity (CMI) to Bordetella pertussis antigens were assessed in a cohort of Italian military school students for whom the coverage of pertussis vaccination was low. The overall prevalence of IgG antibody above the minimum level of detection (MLD) was 71.6% for pertussis toxin (PT), 81% for pertactin (PRN), and 99% for filamentous hemagglutinin (FHA). Levels of IgA antibody to PT above the MLD were detected in 15.9% of the study participants. CMI to FHA, PRN, and PT was positive in 97%, 100%, and 82% of tested individuals, respectively. Only 9.7% of the participants had neither antibody nor CMI specific to B. pertussis antigens. In the 5-month clinical, microbiological, and serological follow-up conducted during a high-risk period of pertussis, no cases of pertussis were detected. These data, in particular CMI, demonstrate that most Italian young adults are specifically primed against B. pertussis, which should be taken into consideration when future policy on pertussis vaccination is being made in Italy.

Adolescent↗
PubMed1998

Mycobactericidal activity of human natural, monoclonal, and recombinant yeast killer toxin-like antibodies.

Human natural (KTAb), murine monoclonal (KTMAb), and single-chain recombinant (KTScFv) candidacidal antibodies representing the internal image of a killer toxin from the yeast Pichia anomala (KT), characterized by a wide spectrum of antibiotic activity, exerted a lethal effect against a KT-sensitive multidrug-resistant isolate of Mycobacterium tuberculosis. KTMAb and KTScFv were produced by the hybridoma and DNA technologies, respectively, from the spleen lymphocytes of animals immunized with the idiotype of a KT-neutralizing MAb (MAb KT4), while KTAb were purified against MAb KT4 from the vaginal fluid of women infected with Candida albicans cells bearing an idiotype-like KT cell wall receptor. Mycobactericidal activity was related to the binding of KTAb, KTMAb, and KTScFv to the cell surface of KT-sensitive bacterial cells and was prevented by specific absorption of KT-like antibodies onto MAb KT4. These data identify a novel potentially useful immunotherapeutic approach to tuberculosis.

Antibodies, Anti-Idiotypic↗
PubMed1998

A 70-kilodalton recombinant heat shock protein of Candida albicans is highly immunogenic and enhances systemic murine candidiasis.

The 70-kDa recombinant Candida albicans heat shock protein (CaHsp70) and its 21-kDa C-terminal and 28-kDa N-terminal fragments (CaHsp70-Cter and CaHsp70-Nter, respectively) were studied for their immunogenicity, including proinflammatory cytokine induction in vitro and in vivo, and protection in a murine model of hematogenous candidiasis. The whole protein and its two fragments were strong inducers of both antibody (Ab; immunoglobulin G1 [IgG1] and IgG2b were the prevalent isotypes) and cell-mediated immunity (CMI) responses in mice. CaHsp70 preparations were also recognized as CMI targets by peripheral blood mononuclear cells of healthy human subjects. Inoculation of CaHsp70 preparations into immunized mice induced rapid production of interleukin-6 (IL-6) and tumor necrosis factor alpha, peaking at 2 to 5 h and declining within 24 h. CaHsp70 and CaHsp70-Cter also induced gamma interferon (IFN-gamma), IL-12, and IL-10 but not IL-4 production by CD4+ lymphocytes cocultured with splenic accessory cells from nonimmunized mice. In particular, the production of IFN-gamma was equal if not superior to that induced in the same cells by whole, heat-inactivated fungal cells or the mitogenic lectin concanavalin A. In immunized mice, however, IL-4 but not IL-12 was produced in addition to IFN-gamma upon in vitro stimulation of CD4+ cells with CaHsp70 and CaHsp70-Cter. These animals showed a decreased median survival time compared to nonimmunized mice, and their mortality was strictly associated with organ invasion by fungal hyphae. Their enhanced susceptibility was attributable to the immunization state, as it did not occur in congenitally athymic nude mice, which were unable to raise either Ab or CMI responses to CaHsp70 preparations. Together, our data demonstrate the elevated immunogenicity of CaHsp70, with which, however, no protection against but rather some enhancement of Candida infection seemed to occur in the mouse model used.

Animals↗
PubMed1998

The pH of the host niche controls gene expression in and virulence of Candida albicans.

Little is known of the biological attributes conferring pathogenicity on the opportunistic fungal pathogen Candida albicans. Infection by this pathogen, as for bacterial pathogens, may rely upon environmental signals within the host niche to regulate the expression of virulence determinants. To determine if C. albicans responds to the pH of the host niche, we tested the virulence of strains with mutations in either of two pH-regulated genes, PHR1 and PHR2. In vitro, PHR1 is expressed when the ambient pH is at 5.5 or higher and deletion of the gene results in growth and morphological defects at neutral to alkaline pHs. Conversely, PHR2 is expressed at an ambient pH below 5.5, and the growth and morphology of the null mutant is compromised below this pH. A PHR1 null mutant was avirulent in a mouse model of systemic infection but uncompromised in its ability to cause vaginal infection in rats. Since systemic pH is near neutrality and vaginal pH is around 4.5, the virulence phenotype paralleled the pH dependence of the in vitro phenotypes. The virulence phenotype of a PHR2 null mutant was the inverse. The mutant was virulent in a systemic-infection model but avirulent in a vaginal-infection model. Heterozygous mutants exhibited partial reductions in their pathogenic potential, suggesting a gene dosage effect. Unexpectedly, deletion of PHR2 did not prevent hyphal development in vaginal tissue, suggesting that it is not essential for hyphal development in this host niche. The results suggest that the pH of the infection site regulates the expression of genes essential to survival within that niche. This implies that the study of environmentally regulated genes may provide a rationale for understanding the pathobiology of C. albicans.

Animals↗
PubMed1998

Antibody and/or cell-mediated immunity, protective mechanisms in fungal disease: an ongoing dilemma or an unnecessary dispute?

Historically there has been controversy on the relative importance of antibody- and cell-mediated immune responses in the protection against fungal pathogens. The controversy was fuelled by the difficulties encountered in obtaining consistent results with polyclonal antibody experiments and I inducing long-lasting immune protection by vaccinations with induce stron cell-mediated responses. Recent studies indicate that both antibody- and cell-mediated immune responses can contribute to host protection against Candida albicans and C. neoformans. At the present time the major issue is not the relative importance of antibody- and cell-mediated immune responses but rather, the mechanisms by which the two arms of the immune system function and cooperate.

Animals↗
PubMed1998

Selected animal models: vaginal candidosis, Pneumocystis pneumonia, dermatophytosis and trichosporosis.

A clear understanding of the pathogenesis of fungal disease remains elusive. While technological advances in molecular biology and microbial genetics have provided scientists with major new insights into both microbial virulence factors as well as host susceptibility to infection, there is currently no substitute for animal models in elucidating microbe-host interactions. Animal models are also essential for the evaluation of new antimicrobial agents, including studies of efficacy, adverse reactions and pharmacokinetics. The single most important advance in animal models in the last decade, has been the availability of genetically unique strains of animals as alternative to animals treated with immunosuppressive drugs for use in studies on microbial virulence and host defence mechanisms. These unique strains of test animals also enhance our understanding of the modes of action of antifungal drugs and their metabolism. Some of these advances will be discussed in this symposium.

Animals↗
PubMed1997

Cell-mediated and antibody responses to Bordetella pertussis antigens in children vaccinated with acellular or whole-cell pertussis vaccines. The Progetto Pertosse-CMI Working Group.

OBJECTIVE: To examine induction and persistence of cell-mediated immunity (CMI) and antibody responses to Bordetella pertussis antigens in infants receiving antipertussis vaccines. DESIGN AND SETTING: A randomized, blinded study of 142 children receiving acellular pertussis vaccines combined with diphtheria-tetanus toxoids (DTaP) (DTaP manufactured by SmithKline Beecham [DTaP-SB], Rixensart, Belgium, and DTaP manufactured by Chiron Biocin [DTaP-CB], Siena, Italy), or a whole-cell pertussis vaccine (DTwP) (Connaught Laboratories Inc, Swiftwater, Pa), or a diphtheria-tetanus (DT) (Chiron Biocine) only vaccine. Three doses of each vaccine were given at 2, 4, and 6 months of age, and CMI and antibody responses were evaluated before and at 1 and 14 months after vaccination. METHODS AND MAIN OUTCOME MEASURES: Cell-mediated immunity was assessed by proliferation of peripheral blood mononuclear cells stimulated in vitro by B pertussis antigens (pertussis toxin, filamentous hemagglutinin, and pertactin). Antibody titers against pertussis toxin, filamentous hemagglutinin, and pertactin were determined by a standardized enzyme-linked immunosorbent assay. RESULTS: A CMI-positive response to at least 1 B pertussis antigen at 1 or both postvaccination assays was detected in 46%, 55%, and 83% of DTwP, DTaP-SB, and DTaP-CB vaccine recipients, respectively. Frequency of CMI response to individual antigens ranged from less than 4.9% against pertussis toxin in DTwP recipients to 52% against pertactin in DTaP-CB recipients. The postvaccination responses measured at 14 months equalled, or had increased frequency or intensity, that of the 1-month postvaccination responses. Elevated antibody titers against the 3 antigens were present in all DTaP recipients 1 month after vaccination and were higher in CMI-positive children than in CMI-negative children. They fell, however, to low, if not negligible, levels 14 months after vaccination. CONCLUSIONS: Acellular pertussis vaccines were better inducers of CMI response than the whole-cell vaccine, particularly against pertussis toxin. Once acquired, CMI persisted, in contrast with the rapid antibody decline. Thus, CMI responses could be a useful adjunct to serology in the evaluation of pertussis vaccine immunogenicity and a better correlate of long-term immunity to B pertussis than antibody titers.

Bordetella pertussis↗
PubMed1997

Possible participation of polymorphonuclear cells stimulated by microbial immunomodulators in the dysregulated cytokine patterns of AIDS patients.

Macrophages and polymorphonuclear cells (PMN) play a major role as cells primarily responsive to microbial biological response modifiers (BRM). Although much attention has been given to macrophages, PMN have been relatively underinvestigated. We have recently studied the responses of PMN from HIV- and HIV+ subjects after stimulation with a powerful immunomodulatory fraction from the cell wall of Candida albicans (MP-F2) and compared this to bacterial lipopolysaccharide (LPS). Both cytokine patterns and PMN anticandidal activity were investigated. MP-F2, like LPS, was an active inducer of interleukin-8 (IL-8), tumor necrosis factor alpha (TNF-alpha), IL-6, and IL-1 beta production by PMN and monocytes from all subjects. IL-12 was also produced by MP-F2-stimulated PMN in the presence of interferon-gamma (IFN-gamma). PMN from HIV+ subjects showed increased in vitro expression of TNF-alpha and IL-6 genes as determined by semiquantitative reverse transcriptase-polymerase chain reaction. In all subjects, cytokine gene expression was strongly stimulated by MP-F2 or LPS and inhibited by IL-10. Production of IL-6 and TNF-alpha protein (measured by ELISA) was higher in PMN from HIV+ subjects in at least one of the conditions tested (unstimulated or stimulated by LPS or MP-F2). However, the amount of the C-X-C chemokine IL-8 was equal in PMN from HIV- and HIV+ subjects. PMN from HIV+ subjects were at least as active in inhibiting candide growth as PMN from HIV- controls. In both groups PMN were equally stimulated by MP-F2 and LPS. Only in severely neutropenic subjects was there some reduction in the anticandidal activity but not in cytokine responses. When appropriately stimulated by microbial BRM, PMN are active producers of pro-inflammatory and immunomodulatory cytokines. This production is not only totally preserved in HIV+ subjects but may be higher than in PMN from HIV- subjects and may be coupled with an efficient anticandida activity. We suggest that during common bacterial or fungal infections PMN may contribute to the dysregulated production of inflammatory cytokines in AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Construction and use of PCR primers from a 70 kDa heat shock protein gene for identification of Candida albicans.

Methods for detection of Candida albicans in culture or biological samples were developed by the use of polymerase chain reaction (PCR) with oligonucleotide primers from C. albicans 70 kDa heat shock protein gene (Cahsp70). The PCR amplifies a 335-base pair fragment which is then hybridized with a non-radioactive probe, leading to the specific identification of C. albicans and its differentiation from all other human pathogenic Candida and/or yeast species. Candida albicans could be rapidly detected in human urine and blood, with a sensitivity of 10 and 50 fungal cells per sample, respectively.

Amino Acid Sequence↗
PubMed1997

Ultrastructural localization of the secretory aspartyl proteinase in Candida albicans cell wall in vitro and in experimentally infected rat vagina.

Detection and ultrastructural localization of aspartyl proteinase (Sap) in Candida albicans experimentally infecting rat vagina were studied. Two Sap-positive (Sap+) and one Sap-negative (Sap-) strains of the fungus, endowed with high and low experimental vaginopathic potential, respectively, were used. Both Sap+ strains produced consistent Sap levels in the rat vagina, while the Sap- strain did not produce any measurable Sap. Electron microscopy of thin sections of chemically-fixed vaginal scrapings showed clear evidence of hyphae of proteolitic strains of C. albicans invading the keratinized epithelial cell layer of the vagina. The fungal cells exhibited a pronounced fibrillar layer on the cell wall with a marked intermixing of fungal and vaginal materials especially pronounced at the hyphal tip. Post-embedding immunogold techniques with the use of anti-Sap polyclonal and the specifically generated monoclonal antibody GF1 showed that Sap was essentially localized in the cell wall of C. albicans early during infection, in a cytological pattern mirroring Sap localization in C. albicans cells grown in Sap-inductive media in vitro. In summary, the data offer a new biochemical and ultrastructural evidence that Sap is actively secreted during experimental rat vaginitis by C. albicans. Cell wall localization of Sap is probably inherent to this active secretion process.

Animals↗
PubMed1997

Therapeutic potential of antiidiotypic single chain antibodies with yeast killer toxin activity.

Single chain fragment (ScFv) antiidiotypic antibodies (antilds) of a killer toxin (KT) from the yeast Pichia anomala have been produced by recombinant DNA methodology from the splenic lymphocytes of mice immunized by idiotypic vaccination with a KT-neutralizing monoclonal antibody (Mab KT4). ScFv KT-like antilds (KTIdAb) react with specific Candida albicans KT cell wall receptors (KTR) exerting a candidacidal activity in vitro could be neutralized by adsorption with Mab KT4. ScFv KTIdAb displayed an effective therapeutic activity in an experimental model of rat candidal vaginitis.

Animals↗
PubMed1997

Responsiveness of human polymorphonuclear cells (PMNL) to stimulation by a mannoprotein fraction (MP-F2) of Candida albicans; enhanced production of IL-6 and tumour necrosis factor-alpha (TNF-alpha) by MP-F2-stimulated PMNL from HIV-infected subjects.

IL-1beta, IL-6, IL-8 and TNF-alpha production by PMNL from 21 HIV-infected (HIV+), including 11 full-blown AIDS, and 20 HIV-uninfected (HIV-) subjects (matched for age and sex to HIV+ ones) was studied by reverse transcriptase-polymerase chain reaction (RT-PCR) and ELISA. PMNL from both categories of subjects were strongly stimulated in their actual cytokine production by a mannoprotein fraction (MP-F2) of Candida albicans, as well as by the bacterial lipopolysaccharide (LPS). These stimulatory effects were apparently due to increased cytokine gene expression and were substantially reversed by the physiological inhibitor IL-10. However, PMNL from HIV+ subjects showed increased IL-6 and TNF-alpha gene expression and produced more IL-6 and TNF-alpha than PMNL from HIV- controls, under similar stimulation conditions. This difference could not be attributed to a given stage of HIV infection, any associated medication, or to a generalized increase of gene expression, as quantitatively similar beta-actin and IL-1beta transcripts were detected. Moreover, no significant difference in IL-8 production by the PMNL from HIV+ and HIV- subjects was observed. Our studies suggest that PMNL from HIV+ subjects might add to other cellular sources of IL-6 and TNF-alpha (e.g. monocytes-macrophages) in contributing to the cytokine-dysregulated pattern typical of the HIV+ patient.

Adult↗
PubMed1997

CD28 costimulation and T lymphocyte proliferative responses in HIV-1 infection.

To investigate whether defective costimulatory signals could be involved in the loss of T lymphocyte functions during HIV-1 infection, we tested the effect of CD28 costimulation on both T cell receptor/CD3 and HIV-1 antigen-induced proliferative responses. Although CD3-mediated responses significantly decreased with more advanced stages of HIV-1 infection, the ability of potentiating the responses through CD28 costimulation was maintained at all stages and did not differ from that of HIV-1- subjects. When CD28 costimulation was studied in lymphocyte cultures stimulated with HIV-1 gp160 or p24, potentiation was seen only when a significant response was present without additional CD28 triggering, namely in subjects receiving active immunization with recombinant gp160. These results confirm the integrity of the CD28 pathway of costimulation during HIV-1 infection, and suggest that lymphocytes responding to soluble HIV-1 antigen are not deleted in HIV-1-infected patients, but do not receive significant priming during the natural course of the infection.

CD28 Antigens↗
PubMed1997

Long-term evaluation of cellular immunity during antiretroviral therapy and immunization with human immunodeficiency virus type 1 (HIV-1) Env glycoprotein in HIV-1-infected persons.

Cellular immune responses to human immunodeficiency virus type 1 (HIV-1) antigens, microbial recall antigens, and CD3 monoclonal antibody were studied in HIV-1-infected asymptomatic patients in a phase II, double-blind trial of immunization with recombinant HIV-1 gp160 in or not in association with zidovudine. A vigorous and persistent lymphoproliferative response (LPR) to HIV-1 Env antigens was observed in vaccinated patients. Neither Env-specific lymphocyte cytotoxicity nor LPR to recall antigens was significantly influenced by gp160 administration. The induction of LPRs to HIV-1 envelope proteins did not show positive effects on the course of HIV-1 infection. Patients treated with zidovudine alone or in combination with the immunogen showed improvement of T lymphocyte responses and transient reduction of viremia. These results suggest that antiretroviral therapy is more beneficial than immunization with gp160 and should always be considered in association with future vaccination and immunotherapeutic interventions in HIV-1-infected subjects.

Adolescent↗
PubMed1997

Suckling CD1 mice as an animal model for studies of Legionella pneumophila virulence.

On the assumption that specific host defences are lower in newborn and infant animals, the susceptibility of CD1 suckling mice to Legionella pneumophila was studied with the hypothesis that this model could detect consistent differences in virulence among Legionella isolates from various clinical and environmental sources. Mice 3-14 days old were indeed markedly susceptible to intraperitoneal challenge with fresh clinical isolates, but not to serially subcultured or type collection strains of L. pneumophila. For example, intraperitoneal inoculation of 10(7) cells of a fresh clinical isolate of L. pneumophila (strain Monza 3) caused 60% mortality of suckling mice in 1 day whereas the same number of cells of a culture-attenuated derivative (strain Monza 3p50) caused <10% mortality in >15 days. Lethal infection by the 'virulent' Monza 3 strain was strictly dependent on mouse age (no death was observed in mice >26 days old), required the inoculation of viable cells and was not related to endotoxin production. The 'virulent' L. pneumophila strain was cleared from mouse lungs less rapidly, while adhering to, and being internalised into the peritoneal exudate cells (PEC) of suckling mice to a greater extent, than the avirulent derivative, as shown by immunofluorescence and confocal microscopy. The Monza 3 strain also induced the production by PEC in vivo of 5-to-10 times more tumour necrosis factor-alpha (TNF-alpha) mRNA than the Monza 3p50 strain. Overall, suckling CD1 mice appear to provide a promising, easily handled, highly reproducible and relatively inexpensive animal model for studies of the virulence of L. pneumophila, and possibly, of the role of pro-inflammatory cytokine production in this phenomenon.

Animals↗
PubMed1997

Vaccine- and antigen-dependent type 1 and type 2 cytokine induction after primary vaccination of infants with whole-cell or acellular pertussis vaccines.

Cytokine profiles were examined 1 month after primary vaccination of infants with a whole-cell pertussis vaccine (wP) (Connaught) or either of two acellular pertussis vaccines, aP-Chiron Biocine (aP-CB) or aP-SmithKline Beecham (aP-SB), each combined with diphtheria-tetanus toxoids (DT), in Bordetella pertussis antigen-stimulated or unstimulated peripheral blood mononuclear cells (PBMC). Pertussis toxin (PT), filamentous hemagglutinin (FHA), and pertactin (PRN) were used as antigens, and the children were defined as responsive when their PBMC proliferated in response to these antigens. The controls were either children who received only DT or children who received pertussis vaccine but whose PBMC did not proliferate upon stimulation with B. pertussis antigens (unresponsive children). Antigen-stimulated PBMC of responsive wP recipients were characterized by an elevated production of T-helper-cell type 1 cytokines gamma interferon (IFN-gamma) and interleukin 2 (IL-2), low to minimal production of IL-5, and no production of IL-4. The PBMC of aP vaccine-responsive recipients showed, in addition to the elevated IFN-gamma production, a consistent, antigen-dependent production of type 2 cytokines (IL-4 and IL-5), with PRN being the most and PT being the least effective antigen. Type 2 cytokine induction was more pronounced in aP-SB than in aP-CB recipients, as shown by the presence of IL-4 mRNA transcripts and higher IL-5 production in the former (161.6 +/- 36 and 47.9 +/- 44 pg/ml [mean +/- standard error for five subjects each], respectively, after PRN stimulation). Appreciable, antigen-unstimulated (constitutive) IFN-gamma production was also detected in PBMC cultures of all vaccinees. However, this spontaneous IFN-gamma production was, in most vaccinees, significantly lower than the antigen-driven cytokine production. In contrast, no constitutive type 2 cytokine production was ever observed in any vaccine group. PBMC from the two control groups (either DT or pertussis vaccine recipients) did not show any type 2 cytokine production, while IFN-gamma production was comparable in both antigen-stimulated and unstimulated conditions. Absence of type 2 cytokines and low levels of constitutive IFN-gamma production were also seen in prevaccination children. Thus, pertussis vaccines induce in infants a basically type 1 cytokine profile, which is, however, accompanied by some production of type 2 cytokines. The latter are more expressed by aP-SB than by aP-CB recipients, and with PRN than with other antigens, and they are minimally expressed in wP recipients and with PT as antigen. Our data also highlight a constitutive IFN-gamma production in infancy, which might reflect natural immunization and/or the burden of concomitant vaccinations and which may have an impact on T-helper-cell cytokine pattern polarization consequent to pertussis vaccination.

Antigens, Bacterial↗