Biomedical subjects

L Romani

Publications and source records attributed to L Romani.

At least 73 records · Page 4Linked to original sources

PubMed1994

Cure of murine candidiasis by recombinant soluble interleukin-4 receptor.

Neutralization of interleukin (IL)-4 by specific antibody exerts therapeutic activity in a murine model of systemic candidiasis characterized by strong T helper type 2 (Th2) responses. To investigate whether recombinant soluble IL-4 receptor (sIL-4R) could be used to block IL-4 action in vivo, mice treated with pharmacologic doses of sIL-4R at the time of infection were examined for progression of disease, development of footpad responses, serum IgE levels, and cytokine production in vitro by CD4+ lymphocytes. Following sIL-4R treatment, persistent ablation of circulating IL-4 detected by ELISA was associated with a cure rate of > 90% in otherwise lethally infected mice, onset of durable protection, and a shift from a predominant Th2 to a Th1 pattern of reactivity. In addition, when administered to genetically susceptible adult mice with gastrointestinal yeast colonization, the sIL-4R stimulated Th1-associated anticandidal resistance.

Animals↗

PubMed1994

A mannoprotein constituent of Candida albicans that elicits different levels of delayed-type hypersensitivity, cytokine production, and anticandidal protection in mice.

To identify major immunogenic constituents of Candida albicans, the effect of a mannoprotein fraction (MP-F2) on the elicitation of a delayed-type hypersensitivity (DTH) reaction, cytokine production, and protection from a virulent Candida challenge in a mouse candidiasis model was studied. In mice immunized with whole cells of a low-virulence strain of C. albicans and thus protected against a challenge with a highly virulent strain of this fungus, MP-F2 was able to elicit a strong DTH response that was accompanied by splenocyte proliferation in vitro in the presence of Candida antigen. The supernatants of MP-F2-stimulated splenocyte cultures contained gamma interferon (IFN-gamma, a typical CD4+ T helper-1 (Th1) cytokine, but no interleukin-4, (IL-4), a typical CD4+ Th2 cytokine. IFN-gamma was produced by CD4+ cells, and its level could be greatly increased by the addition of anti-IL-4 or, mostly, anti-IL-10 antibodies to the CD4+ cell cultures. Upon a suitable schedule of immunization, MP-F2 was also able to induce a vigorous DTH response in Candida-uninfected mice, a response that could be efficiently transferred into naive recipients by CD4+ cells from the spleens of MP-F2-immunized mice. The immunization described above also conferred to mice a low degree of protection against a virulent Candida challenge, both in terms of median survival time and in the number of Candida cells in the kidney. However, while DTH induction by MP-F2 was as strong as that induced by whole cells, MP-F2-induced protection was significantly weaker than that conferred by Candida whole-cell immunization. Mice immunized with either MP-F2 or Candida whole cells had an inverted ratio between the number of CD4+ splenocytes producing IFN-gamma and that of cells producing IL-4, compared with nonimmunized animals. However, the number of IL-4-producing CD4+ cells was significantly higher in MP-F2-vaccinated, weakly protected mice than in Candida whole-cell-vaccinated, highly protected animals. Overall, our data suggest that the MP-F2 fraction contains one or more major immunogens of C. albicans which are capable of interfering with the balance of CD4+ Th1 and Th2 responses that is so critical in the outcome of host-Candida relationship and are thus potentially relevant in the mechanisms of Candida-specific DTH regulation and protection.

Animals↗

PubMed1994

Tolerance to staphylococcal enterotoxin B initiated Th1 cell differentiation in mice infected with Candida albicans.

Staphylococcal enterotoxin B (SEB) is a bacterial superantigen that specifically activates T cells bearing V beta 8 T-cell receptor domains, which eventually leads to a long-lasting state of clonal anergy accompanied by selective cell death in the targeted CD4+ subset. Because the superantigen is known to promote Th1 cell differentiation in vitro, we have investigated the effect of SEB treatment on the course of Th2-associated progressive disease in mice infected systemically with Candida albicans. On the basis of the kinetics of SEB-induced changes in CD4+ cells and production in sera of interleukin 4 (IL-4), IL-10, and gamma interferon, we obtained evidence that V beta 8+ cell anergy concomitant with infection abolished the early IL-4/IL-10 response of the host to the yeast, ultimately leading to a state of resistance characterized by gamma interferon secretion in vitro by antigen-specific CD4+ cells. In contrast, SEB administered near the time of challenge resulted in accelerated mortality. Significant resistance to infection was also afforded by exposure of mice to a retrovirally encoded endogenous superantigen. These data suggest that CD4+ V beta 8+ T cells play an important role in vivo in the initiation of a Th2 response to C. albicans and that suppression of their activity may alter the qualitative development of the T-cell response and the outcome of infection.

Animals↗

PubMed1994

Cell-mediated immunity in the course of cervical ectropion.

In the present study we evaluated cellular immunitary response in course of asymptomatic ectropion. Biopsies of the injured and healthy zones of the exocervix were carried out. All biopsies were examined by an immuno-histo-chemical method (Avidin-Biotin Complex, ABC) with monoclonal antibodies, in order to phenotype T lymphocytic subpopulations, in particular T helper lymphocytes (CD4), T suppressor lymphocytes (CD8) and Langerhans cells (CD1), which are basic elements of the monocytic-macrophagic series. Our preliminary findings showed a reduction of CD4, CD8 and CD1 lymphocytic subpopulations in ectropion zones, while these subpopulations are normally present in healthy zones of the exocervix. These findings support the hypothesis that, in ectropion, as in HPV infections and in CIN, a localized immuno-deficiency may appear and depress immuno-surveillance and cell-mediated response. In conclusion, it may be supposed that ectropion represents a non-stable lesion, which therefore needs suitable therapeutic intervention.

Adult↗

PubMed1993

CD4+ subset expression in murine candidiasis. Th responses correlate directly with genetically determined susceptibility or vaccine-induced resistance.

Previous work has shown that in hybrid (BALB/cCr x DBA/2Cr)F1 mice the development of a fatal disseminated disease by systemic infection with virulent Candida albicans is associated with the detection of strong Th2-like responses. However, a predominant Th1-like response and long-lived antifungal protection are induced by vaccinating these mice with live blastospores of attenuated C. albicans strains. When injected into DBA/2Cr mice, one such live vaccine strain was found in the present study to result in a progressive disease characterized by strong Th2 responses. Elevated serum IgG1, IgA, and IgE responses, weak or absent footpad reactions, sustained production in vitro of Th2 (IL-4 and IL-10) but not Th1 (IL-2 and IFN-gamma) cytokines by CD4+ cells, and eosinophilia were all detected in DBA/2 mice after infection with the attenuated vaccine. This was in marked contrast with the development of strong Th1 responses and persistent anticandidal protection in similarly infected, H-2-compatible BALB/cCr mice. Therefore, our data suggest that the type of Th response that predominates in mice after C. albicans infection correlates with genetically determined susceptibility or vaccine-induced resistance. Moreover, the genetic control of this resistance may not be associated with the H-2 complex.

Animals↗

PubMed1993

Interleukin-4 and interleukin-10 inhibit nitric oxide-dependent macrophage killing of Candida albicans.

Mouse peritoneal and splenic macrophages treated with interferon-gamma (IFN-gamma) and infected with the yeast Candida albicans expressed high fungicidal activity in vitro that correlated with increased nitrite concentrations in culture supernatants. Both effects were reduced by an inhibitor of nitric oxide (NO) synthesis which, in vivo, impaired the animals' ability to mount a footpad reaction and clear the fungus from infected organs. Because T helper type-2 (Th2) cytokines in candidiasis are known to limit the expression of protective Th1 functions, we tested the effect of interleukin (IL)-4 and IL-10 on candidacidal activity and NO production of IFN-gamma-activated macrophages. Fungal killing and NO secretion were inhibited, in a dose-dependent manner, by the two cytokines either separately or in combination. Impaired candidacidal activity was also demonstrable in the presence of monoiodoacetic acid, an inhibitor of phagocytosis. These data demonstrate that NO is involved in macrophage killing of C. albicans and support the notion that regulation of Th1 effector function by IL-4 and IL-10 might involve modulation of NO synthesis.

Animals↗

PubMed1993

Low-dose streptozotocin-induced diabetes in mice. II. Susceptibility to Candida albicans infection correlates with the induction of a biased Th2-like antifungal response.

We have previously found that the development of fatal disseminated candidiasis correlates with the detection of a strong Th2 response, while protective antifungal immunity is associated with a predominant Th1 response. In the present study we verified the hypothesis that an altered antifungal Th response could be responsible for the high susceptibility of diabetic mice to systemic Candida albicans infection. Outbred CD1 mice rendered diabetic with multiple low doses of the pancreatic islet beta-cell toxic, streptozotocin, develop a fatal systemic infection when injected with low-virulence C. albicans cells. Progressive disease was found to be associated with the presence in the serum of IgA, IgE, and IgG1 Candida-reactive specific antibodies, absent footpad reactions, and elevated production in vitro of the Th2 cytokines IL-4, IL-6, and IL-10 but not the Th1 cytokine IFN-gamma. Both the Th2 and Th1 (IL-2 and IFN-gamma) cytokines were produced in vitro by CD4+ lymphocytes from noninfected diabetic mice that, in addition, showed a noticeable footpad reaction to Candida antigens. Thus, it appears that a perturbation in the anticandidal T helper responses resulting in the induction of a biased Th2-like antifungal response renders diabetic mice highly susceptible to systemic C. albicans infection.

Animals↗

PubMed1993

Mucosal and systemic T helper cell function after intragastric colonization of adult mice with Candida albicans.

In 85% of adult DBA/2 mice inoculated intragastrically with Candida albicans, significant numbers of yeast cells were recovered from the gastrointestinal tract for up to 4 weeks, with the animals eventually clearing infection in the absence of systemic disease despite the occurrence of localized, self-limiting foci of mucosal involvement in their stomachs. Two major findings in colonized mice were defective production of IgA, interleukin (IL)-4, and IL-5 by Peyer's patches lymphocytes and increased numbers of interferon-gamma-producing T cells in mesenteric lymph nodes and spleens. Relatively low levels of circulating antibodies of T helper type 2 (Th2)-dependent isotypes were also found in colonized mice, which exhibited strong footpad responses and increased resistance to systemic reinfection. Unlike systemic challenge, gastrointestinal colonization of adult immunocompetent DBA/2 mice with C. albicans appears to be an effective stimulus for the systemic development of protective Th1 responses.

Animals↗

PubMed1993

Raven's colored progressive matrices: a normative study of a random sample of healthy adults.

Raven's Colored Progressive Matrices Test (RCPM) was administered to 894 normal healthy adults who were randomly selected in six Italian cities and in the Republic of San Marino. Gender, age, and education significantly influenced overall test performance, and performance on different RCPM subsets. Findings from this large random sample provide demographic corrections to test scores for use in clinical practice.

Adult↗

PubMed1993

Natural killer cells do not play a dominant role in CD4+ subset differentiation in Candida albicans-infected mice.

The effects of in vivo administration of monoclonal antibodies against NK-1.1-bearing cells on the early production of gamma interferon (IFN-gamma) in vitro and development of Th1-associated immunity were studied in mice infected with a live vaccine strain of Candida albicans. At 1 and 4 days postinfection, natural killer (NK) cell-enriched fractions from the spleens of antibody-treated mice displayed a dramatic reduction in 5E6+ lymphocytes and negligible anti-YAC-1 cytotoxic activity in vitro. Nevertheless, the frequency of IFN-gamma-producing cells in those fractions was reduced by less than half, on average, by anti-NK-1.1 treatment in vivo. In addition, the antibody-treated and infected mice demonstrated unchanged T helper cell responses, as measured by yeast-specific footpad reactions, resistance to reinfection, occurrence of antibodies of different isotypes, and production in vitro of interleukin-2 (IL-2), IFN-gamma, IL-4, and IL-10 by CD4+ cells. Therefore, although NK cells may contribute to early IFN-gamma production in Candida-vaccinated mice, these cells apparently do not play a dominant role in the qualitative development of yeast-specific T helper responses.

Animals↗

PubMed1992

Immunogenic tumor variants induced by drug treatment of the L5178Y lymphoma: search for serologically defined antigens at the clonal level.

Highly immunogenic tumor variants are generated by in vitro or in vivo treatment of the murine L5178Y lymphoma line with triazene derivatives. Most of these variants express new transplantation- and antibody-defined antigens that previous studies have shown to be closely related. One such 80-kDa protein on the surface of clone-D cells was found to be related to xenotropic MuLV gp70 molecules. To investigate the possible relevance of clone-D data to general properties of immunogenic variants in this tumor model system, polyclonal syngeneic antisera raised to a panel of immunogenic clones (including clone D) of the drug-treated L5178Y lymphoma line were employed in the immunoprecipitation of cell-surface and intrinsically labeled variant cells. In all clones, 1- and 2-dimensional electrophoretic analysis of the immunoprecipitates detected an antigen of approximately 80 kDa, and 35S-labeled 80-kDa molecules could be cross-precipitated from all clones by the panel of clone-specific antisera. In addition, 45- and 30-kDa components were also found in metabolically labeled variant cells. While the surface 80-kDa component was reactive with anti-xenotropic gp70 antibodies, the 30-kDa molecule was removed by anti-gag p30 antibody in sequential immunoprecipitation experiments. These data suggest that expression of aberrant, retrovirus-related proteins is a common finding in immunogenic cells of the drug-treated L5178Y lymphoma line.

Animals↗

PubMed1992

Neutralizing antibody to interleukin 4 induces systemic protection and T helper type 1-associated immunity in murine candidiasis.

An interleukin 4 (IL-4)-specific monoclonal antibody (mAb) was administered to mice infected systemically with the yeast Candida albicans, and the animals were monitored for mortality, development of delayed-type hypersensitivity, production of antibodies of different isotypes, release of IL-2, IL-4, IL-6, and interferon gamma (IFN-gamma) in vitro by splenic CD4+ lymphocytes, and levels of IL-4 and IFN-gamma mRNA in these cells. Neutralization of IL-4 by three weekly injections of mAb in several independent experiments resulted in an overall cure rate of 81% versus 0% of controls. Cure was associated with efficient clearance of the yeast from infected organs and histologic evidence of disease resolution, detection of strong T helper type 1 (Th1) responses, and establishment of long-lasting protective immunity. Soon after infection, and as a result of the first or second injection of mAb, there was a decrease in IL-4 mRNA in CD4+ cells, which was accompanied by an increase in the levels of IFN-gamma-specific transcripts. Our data thus indicate that the production of IL-4 by Th2 cells may limit Th1-associated protective immunity in murine candidiasis.

Animals↗

PubMed1992

Antigen-specific cytolysis of infected cells in murine candidiasis.

Immune L3T4+ and Lyt-2+ lymphocytes play an important role in the acquired resistance of mice to challenge with virulent Candida albicans, and release macrophage-activating cytokines in response to yeast cells in vitro. To determine whether antigen (Ag)-specific cytotoxic T lymphocytes are generated during fungal infection, purified L3T4+ and Lyt-2+ lymphocytes from immunized mice were cultured in the presence of syngeneic accessory cells, Candida Ag, and IL-2. Yeast-infected bone marrow macrophages and peritoneal exudate neutrophils were used as target cells in a standard 51Cr release assay. Ag-specific, MHC-unrestricted lysis of infected macrophages was evident with immune Lyt-2+ cells after 5-10 days in culture. Under the same experimental conditions, the cytotoxic activity of L3T4+ cells was negligible, but its expression could be induced by the addition of anti-CD3 antibody. Culturing immune Lyt-2+ cells for shorter periods of time (1-2 days) resulted in preferential lysis of infected neutrophils. In addition, at limiting effector cell numbers, Ag-specific MHC-restricted lymphocytes with cytotoxic activity to infected macrophages could be identified. We suggest that C. albicans infection stimulates multiple cytotoxic T-cell precursors with varying recognition stringency, which may have an important role in antifungal resistance in vivo.

Animals↗

PubMed1992

O6-methylguanine-DNA methyltransferase activity and induction of novel immunogenicity in murine tumor cells treated with methylating agents.

To investigate the mechanism of the generation of immunogenic tumor variants by mutagenic drugs, murine leukemia cells exhibiting different sensitivity to killing by the alkylator 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and different ability to repair O6-methyl-guanine in their DNA were treated in vitro with a series of methylating agents, including triazene derivatives, temozolomide, and streptozotocin. At the population level, we found that BCNU-resistant cells (L1210/BCNU) that appeared to be cross-resistant to killing by a dimethyltriazene and expressed high levels of O6-methylguanine-DNA methyltransferase activity (mer+ phenotype) failed to generate highly immunogenic variant sublines on repeated exposure to the methylating agents. In contrast, all cells (L1210) that were susceptible to DNA alkylation damage and deficient in O6-methylguanine repair (mer-) developed immunogenic variant sublines. A noticeable exception was represented by streptozotocin treatment, which was equally effective in mer+ and mer- cells. At the clonal level, a single exposure to streptozotocin or a triazene derivative resulted in a high incidence (33% and 50%, respectively) of immunogenic cell generation in mer- cells only. In mer+ cells, streptozotocin treatment led to a 33% incidence of immunogenic clones only when the cells were concurrently exposed to O6-methylguanine as a free base. The activity of O6-methylguanine-DNA methyltransferase in mer+ cells was greatly reduced by treatment with O6-methylguanine or streptozotocin, and the combination of the two drugs led to enzyme levels similar to those observed in mer- cells. Taken together, these data suggest that the mechanism of O6-alkylation may be operative in the induction of novel tumor-cell antigenicity by methylating agents.

Alkylating Agents↗

PubMed1992

Naming disorders and semantic representations.

The status of semantic conceptual structures in aphasia was investigated with relation to naming disorders in spontaneous and constrained speech production. A battery of six tasks was administered to 25 control subjects and 25 aphasics: spontaneous speech production (from which the percentage of nouns was calculated), confrontation naming, understanding class relationships (verbal and pictorial), and understanding thematic relationships (verbal and pictorial). Results indicated the important role of taxonomic abilities for naming, while other conceptual structures (i.e., thematic relations) do not seem to play any important role in the process of naming. These results are discussed in terms of the internal organization of semantic information.

Adolescent↗

PubMed1992

Involvement of the Th1 subset of CD4+ T cells in acquired immunity to mouse infection with Trypanosoma equiperdum.

Heat- or merthiolate-inactivated Trypanosoma equiperdum was administered to recipient mice that were subsequently challenged with viable inocula of the same stabilate. Only mice inoculated with merthiolate-killed parasites were completely protected from a challenge inoculum of 10(3) trypanosomes, an effect that was abolished by prior immunosuppression of mice. Immune sera from protected animals contained high levels of interferon (IFN)-gamma and specific IgG2a antibodies. Spleen cells from these mice produced high amounts of interleukin (IL)-2 and IFN-gamma in vitro in response to specific antigen or concanavalin A, whereas splenocytes from mice receiving heat-killed parasites produced high amounts of IL-6. In contrast, the production of tumor necrosis factor (TNF)-alpha and colony-stimulating activity (CSA) was not significantly different in mice receiving either killed parasite preparation. The protection in immunized mice was associated with the detection of strong delayed-type hypersensitivity (DTH) to T. equiperdum antigens, an effect that could be adoptively transferred onto naive recipients by specifically immune CD4+ lymphocytes. These results suggest that the development of protective immunity in mice to T. equiperdum by our immunization protocol may involve the activity of helper/DTH T cells, particularly those of the Th1 subset.

Animals↗

PubMed1992

Drug-induced modulation of IL-2 production in experimental murine trypanosomiasis.

In this study we evaluated the effects of N-acetyl-cysteine and indomethacin in restoring IL-2 producing ability in vitro of splenocytes from mice infected with Trypanosoma equiperdum. Spleen cells from these mice were found to produce significantly lower levels of interleukin-2 (IL-2) in response to mitogen stimulation than spleen cells from uninfected control mice. This was accompanied by considerable suppression of IL-2-receptor expression, which was not attributable to the elimination of a particular T-cell subset. Impairment of IL-2 production was not due to a primary defect in L3T4+ T-cells, but rather to the presence of both adherent and non-adherent suppressor cells that apparently acted via prostaglandin-independent and dependent mechanisms. In fact, the IL-2-producing ability of lymphocytes from infected mice could be efficiently restored by in vitro exposure to N-acetyl-cysteine or indomethacin.

Acetylcysteine↗

PubMed1992

Tumor-specific L3T4+ and Lyt-2+ lymphocytes in mice primed to mutagenized cell variants.

We have investigated the tumor-specific reactivity of different T-cell subsets from mice primed with clonal variants of L5178Y and P815 cells treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). In both tumor systems, anti-parental tumor immunity and protection against non-immunogenic clones were only induced by vaccinating the hosts with highly immunogenic cell variants, and the effect correlated with the detection of TATA-specific delayed-type hypersensitivity (DTH) reactions. The footpad reaction was transferable with spleen cell populations from immunized mice, and enrichment of splenic lymphocytes in L3T4+ but not Lyt-2+ lymphocytes increased the footpad swelling. Unfractionated spleen cell populations from immunized mice released high amounts of IL-2 and IFN-gamma in vitro in response to parental antigens. Purified L3T4+ and Lyt-2+ lymphocytes also produced IFN-gamma when incubated in vitro with the parental tumors and accessory cells. It is suggested that the mechanisms of anti-parental tumor immunity induced by MNNG-treated variants may be similar to those described previously for triazene-xenogenized L5178Y/DTIC cells, and may involve induction of a tumor-specific DTH reaction and IFN-gamma-mediated stimulation of non-specific tumoricidal effects.

Animals↗