Biomedical subjects

P Marconi

Publications and source records attributed to P Marconi.

At least 37 records · Page 2Linked to original sources

PubMed1998

High-efficacy thymidine kinase gene transfer to ovarian cancer cell lines mediated by herpes simplex virus type 1 vector.

In this report, a replication-defective herpes simplex virus type 1 (HSV-1) vector has been employed to deliver the Escherichia coli LacZ and HSV thymidine kinase (HSVtk) genes to six human ovarian carcinoma cell lines and the efficacy of gene transfer compared to that of adenoviral vectors in vitro. The transduction efficiency of the LacZ-containing virus TOZ.1 was evaluated qualitatively and quantitatively following infection of the different ovarian cancer cell lines. The therapeutic ability of the HSV-T3 vector, which contains the HSVtk gene, was additionally investigated in comparison to the AdCMVHSVTK. Our results show that HSV-1-mediated gene transfer is quantitatively superior to adenoviral vector in five of the six ovarian cancer cell lines at a 100-fold lower dose in vitro. Our preliminary studies suggest that HSV-1 may be a promising alternative vector for ovarian cancer gene therapy.

Cell Division↗

PubMed1998

Implications of maturation for viral gene delivery to skeletal muscle.

Different viral vectors have been analyzed as gene delivery vehicles to skeletal muscle for potentially therapeutic purposes. In this review, we evaluate the application of retroviral, adenoviral, and herpes simplex viral vectors to deliver genes to skeletal muscle and focus on the dramatic loss of viral transduction detected throughout muscle maturation. Recent results suggested that there are several factors involved in the reduced viral transducibility of mature skeletal muscle: muscle cells become post-mitotic in an early stage, the extracellular matrix develops into a physical barrier, and a loss of myoblast mediation occurs since myoblasts progressively become quiescent. Approaches to improve viral gene delivery to mature skeletal muscle may include the use of particular enzymes to increase the permeability of the extracellular matrix, the pre-treatment of the muscle with a myonecrotic agent to induce myoblast mediation, or the application of the myoblast-mediated ex vivo gene transfer.

Adenoviridae↗

PubMed1998

Group B streptococci persist inside macrophages.

Group B streptococci (GBS) are an important cause of neonatal sepsis, pneumonia and meningitis. In the early phase of infection, macrophages and polymorphonuclear cells (PMN) are the first immune cells that interact with GBS. In this in vitro study, to gain insight into GBS-macrophage interaction in the absence of type-specific antibodies, we examined the features of GBS survival in thioglycollate-elicited murine peritoneal macrophages and the effect of GBS on the protein kinase C (PKC)-dependent transduction pathway. Our results demonstrate that type Ia GBS, strain 090 (GBS-Ia) and type III GBS strain COH 31r/s (GBS-III), after in vitro phagocytosis survive and persist intracellularly in macrophages for up to 24 and 48 hr, respectively. However, macrophage activation by interferon-gamma (IFN-gamma) and lipopolysaccharide from Escherichia coli (LPS) caused a significant reduction in the time of intracellular persistence. Macrophage activation by IFN-gamma and LPS seems to be a multifactorial event involving multiple intracellular signal pathways also including PKC. Since PKC is one of the components in the signal network leading to macrophage activation and an important target for several intracellular micro-organisms, we wondered whether PKC could have a role in intracellular GBS survival. Both PKC depletion by treatment with phorbol 12-myristate 13-acetate (PMA) for 18 hr and PKC inhibition by Calphostin C rendered macrophages more permissive for the intracellular GBS survival. Furthermore, GBS-infected macrophages were unable to respond to PMA and LPS, activators of PKC, by inducing antimicrobial activity. The ability of GBS to impair PKC-dependent cell signalling was also demonstrated by the reduced c-fos gene expression in GBS-infected macrophages with respect to control macrophages, after LPS stimulation. In conclusion, our results indicate that GBS survive in macrophages and impairment of PKC signal transduction contributes to their intracellular survival.

Animals↗

PubMed1998

Cytokine response to group B streptococcus infection in mice.

This study was undertaken to better understand the complex relationship between specific and non-specific host defence mechanisms and group B streptococci (GBS). A comprehensive kinetics analysis of cytokine mRNA expression was performed, by Northern blot assay, in peritoneal exudate cells (PEC) and spleen cells (SC) recovered from CD-1 mice at various times during the course of an intraperitoneal infection with a lethal dose (5 x 10(3) microorganisms/mouse) of type Ia GBS, reference strain 090 (GBS-Ia). Analysis of cytokines involved in the development of a specific TH response shows that GBS-Ia in PEC induce only a weak increase of IL-2 mRNA expression and in SC a cytokine pattern characterized by IL-2, IFN-gamma and IL-12 in the absence of IL-4, IL-5 and IL-10. This selected cytokine pattern could provide appropriate conditions for the development of a TH1 response. Analysis of inflammatory cytokines, which are usually induced early during an in vivo infection, shows that there is a significant expression of mRNA specific for IL-1beta, TNFalpha and IL-6, both in PEC and SC only at 24 h which persists at a high level until 36 h. This delayed cytokine induction, accompanied by the contemporary activation of splenic phagocytic cells, occurs only when the number of GBS-Ia is extremely high. In fact, at 24 h GBS-Ia have heavily colonized all organs. In vitro infection of thioglycollate-elicited peritoneal macrophages confirms that the ability of GBS-Ia to induce a strong inflammatory cytokine response depends strictly on the number of infecting microorganisms. Indeed, macrophages respond to GBS-Ia with a very rapid induction of IL-1beta and TNFalpha mRNA when infected at a ratio of 1:10, but not at 100:1. Two major observations emerged from this study: (1) GBS-Ia, by inducing a cytokine pattern which seems to favour development of a TH1 response, could evade antibody production essential for resistance to GBS; and (2) inflammatory cytokine response is induced when a heavy microbial invasion of the host has already occurred. These novel features of GBS-Ia could contribute to the development and progression of lethal infection in mice.

Animals↗

PubMed1997

Progress in development of herpes simplex virus gene vectors for treatment of rheumatoid arthritis.

Arthritis is presently incurable and poorly treatable, but there are good grounds for expecting gene therapy to improve matters considerably. Although local ex vivo delivery of anti-arthritic genes to the synovial lining of joints has shown considerable promise, intraarticular gene delivery may be desirable. Herpes simplex virus (HSV) may be a viable vector for in vivo transfer of anti-arthritic genes to joints. HSV has the advantages of high infectivity, large carrying capacity and high titer. The large packaging capacity would permit the inclusion of multiple anti-arthritic genes and necessary regulatory elements. Recombinant vectors produced by this laboratory infect synovial cells efficiently, permitting prolonged expression of transgenes in vitro and in vivo without evidence of cytotoxicity. Further improvements to this vector system include taking advantage of an endogenous HSV 'stealthing' gene, ICP47, which interferes with formation of antigen-class I complexes. Inclusion of inducible promoters to appropriately regulate expression of anti-arthritic genes should further improve this system.

Journal Article↗

PubMed1997

Gene transfer to muscle using herpes simplex virus-based vectors.

The main goal of gene therapy for Duchenne muscular dystrophy (DMD) is to restore dystrophin into as many muscle cells as necessary to be therapeutic. Herpes simplex virus type 1 (HSV-1) represents a promising new viral vector capable of efficient transduction of myofibers in vivo. The viral genome is large and can accommodate multiple or large non-viral genes including the full-length dystrophin. Here we report on the use of a replication defective HSV-1 mutant vector (DZ) deleted for the essential immediate early (IE) gene ICP4 for studies of reporter gene transfer and expression following direct inoculation of mouse skeletal muscle. Our initial experiments showed that HSV-1 can efficiently infect and express a foreign reporter gene in myoblasts and myotubes in vitro. Furthermore, the intramuscular inoculation of HSV-1 resulted in transduction of a significant number of muscle fibers in newborn mice and some muscle fibers in adult animals. We have attempted to exploit these features to develop new HSV mutant vectors for dystrophin gene delivery to DMD muscle, however two impediments to using this virus for muscle gene delivery have to be overcome: namely viral cytotoxicity and the differential transducibility with HSV-1 throughout the development of muscle fibers. To solve the first problem, virus mutants deleted for the immediate early (IE) genes (ICP4, ICP22, ICP27 and UL41) were constructed and the multiple deleted virus was greatly reduced in cytotoxicity relative to our first generation HSV vector strains. Current work is aimed at incorporating full-length dystrophin under muscle specific promoter (muscle creatine kinase MCK) into these new viral vectors. To address the second problem we have analysed by immunohistochemistry the spreading of the HSV-1 in newborn versus adult muscles to determine whether mature basal lamina which surrounds the adult muscle fibers blocks the HSV-1 entry into the mature muscle fibers.

Animals↗

PubMed1997

Risk for atrial fibrillation in patients with hypertrophic cardiomyopathy assessed by signal averaged P wave duration.

OBJECTIVE: To assess the relation between P wave duration and the occurrence of atrial fibrillation in hypertrophic cardiomyopathy (HCM). DESIGN: High resolution signal averaged electrocardiography was used in 110 patients with HCM to determine whether patients at risk for paroxysmal atrial fibrillation could be detected during sinus rhythm by measuring P wave duration. Filtered P wave duration was measured manually, over an average of 300 beats per patient. RESULTS: During follow up, 18 patients (16%) had at least one one clinical episode of paroxysmal atrial fibrillation, including four patients whose initial episode followed the signal averaged electrocardiogram. The 18 patients with overt atrial fibrillation had greater P wave duration than the 69 patients who did not develop atrial fibrillation: 150 (SD 20) v 126 (14) ms; P < 0.001. Another 23 patients without clinically evident atrial fibrillation had prolonged bursts of the arrhythmia on Holter recording, and showed a P wave duration (138 (15) ms) intermediate between patients with and without clinical atrial fibrillation. In assessing risk for atrial fibrillation, P wave duration > or = 140 ms was associated with sensitivity, specificity, and positive predictive accuracy values of 56%, 83%, and 66%. Multivariate analysis showed that duration of the P wave was the only independent variable associated with occurrence of atrial fibrillation; if P wave duration > or = 140 ms was combined with left atrial enlargement > 40 mm, the specificity and positive predictive accuracy for atrial fibrillation increased to 93% and 78%. CONCLUSIONS: Measurement of P wave duration in sinus rhythm by high resolution signal averaged electrocardiography may be a useful non-invasive clinical tool for identifying patients with HCM likely to develop electrical instability and atrial fibrillation.

Adolescent↗

PubMed1997

Herpes simplex virus vectors for gene transfer to the nervous system.

Herpes simplex virus (HSV) represents a candidate gene transfer vector for the treatment of nervous system disease. It has many natural biological features which make it attractive for gene delivery to a variety of tissues. The virus naturally establishes a latency in sensory neurons of the peripheral nervous system, wherein the virus in maintained as an extrachromosomal DNA element in the absence of viral lytic gene expression without altering the metabolism of the host neuron. The virus possesses a neuronal latency-specific promoter system which remains active long-term, while other viral and cellular promoters are repressed. Replication defective virus recombinants have been engineered to delete multiple essential immediate early gene functions rendering these new mutants significantly less cytotoxic to neurons and other cells in culture. Further developments in regulating transgene expression and reducing virus toxicity will continue to aid the design and use of these vectors for therapeutic applications for the nervous system.

Animals↗

PubMed1996

Replication-defective herpes simplex virus vectors for gene transfer in vivo.

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Animals↗

PubMed1996

Signal-averaged P-wave duration and risk of paroxysmal atrial fibrillation in hyperthyroidism.

The onset of atrial fibrillation (AF) in hyperthyroid patients constitutes an unfavorable clinical event associated with high risk of cardiovascular complications, occurring in approximately one fifth of patients. Therefore, it is advantageous to define noninvasive markers that may identify patients at risk. The high-resolution, signal-averaged electrocardiogram was used to evaluate the relation between P-wave duration and occurrence of paroxysmal AF in a group of 50 patients with hyperthyroidism, of whom 24 had a history of paroxysmal AF and 26 did not. Filtered signal-averaged P-wave duration was measured over an average of 300 beats/patient while in sinus rhythm, both at the time of first diagnosis of hyperthyroidism and after restoration of euthyroidism by medical treatment. The 24 patients with paroxysmal AF had significantly greater P-wave duration than the 26 patients without it (135 +/- 7 vs 124 +/- 9 ms; p = 0.001). A P-wave duration cut-off value of 130 ms held specificity, sensitivity, and positive predictive accuracy values of 79%, 85%, and 83%, respectively. Of several variables, multivariate analysis showed P-wave duration to be the only independent variable significantly associated with the occurrence of paroxysmal AF. Thus, the high-resolution signal-averaged electrocardiogram may be a useful noninvasive clinical tool for the identification of electrical instability associated with paroxysmal AF in hyperthyroid patients.

Adult↗

PubMed1996

Activation of cytokine genes during primary and anamnestic immune response to inactivated c. albicans.

Recent evidence suggests that after repeated stimulations with inactivated C. albicans (CA) cells, CD2F1 mice respond with a cytokine pattern typical of T-helper 1 (ThI) subset development. The purpose of this study was to analyse the sequence of immunological events which, soon after priming mice with CA, lead to the development of primary and anamnestic response. A comprehensive kinetics analysis of cytokine mRNA expression was performed by Northern blot assay, in peritoneal exudate cells (PEC), at different phases of immune response to CA: after priming (one i.p. injection of 2 x 10(7) CA cells mouse), during development of the primary immune response (five progressive CA i.p. injections over a 2-week period) and in the anamnestic response (CA booster 30 days after the primary response). In vitro assays were performed 2 and 24 hr after every CA stimulation. The response to CA priming was characterized by an early and high expression of interleukin-2 (IL-2) and IL-1 beta mRNAs At 24hr. IL-2 mRNA was still at a high level, while IL-1 beta had greatly decreased. A weak expression of IL-10 was only induced at 2 hr. whereas IL-12 p40 subunit, interferon-7 (IFN-7) IL-4 and IL-5 mRNAs were undetectable. In this phase no in vitro proliferative response of PEC to CA was observed, whereas a significant natural killer (NK) activity was induced. From the second CA injection, the IFN-7 mRNA was already induced at 2 hr. Its expression level increased progressively with the number of CA injections persisting up to 24 hr after the fifth stimulation. A progressive increase of IL-2 mRNA expression was also induced whereas IL-1 beta and IL-10 mRNAs were always transiently expressed at 2 hr at levels similar to those observed after the priming. IL-12 p40 subunit. IL-4 and IL-5 mRNAs were never detectable. The expression of this selected cytokine pattern typical of Thl response was correlated with the development of CA-specific T lymphocytes as confirmed by the in vitro proliferative response of CA-5d-induced PEC to CA. NK activity also increased progressively with the number of CA injections and after the fifth stimulation lymphokine-activated killer (LAK) activity was also induced. The anamnestic response to CA was characterized by a very quick induction of high levels of IL-2, II N-gamma and IL-1 beta mRNAs. IL-2 and IFN-gamma mRNAs remained high up to 24 hr while IL-1 beta mRNA decreased strongly. A weak, transient expression of IL-10 mRNA was induced at 2 hr whereas the IL-12 p40 subunit, IL-4 and IL-5 mRNAs were not detectable. The presence of CA-specific memory lymphocytes was confirmed by the in vitro specific proliferative response of PEC to CA. CA booster caused also a very rapid and high level of NK/LAK activation. In conclusion, these results indicate that CA is able to progressively trigger differential on of the Th1 subset which develops in the absence of IL-12, and that Th memory cells retain the same selected Th1 cytokine profile developed in the primary immune response.

Animals↗

PubMed1996

Activity inhibition of cytolytic lymphocytes by omeprazole.

This study examined the in vitro effect of omeprazole (OM) on various types of murine cytocidal lymphocytes. The results show that OM caused a strong inhibition of basal natural killer (NK) activity in spleen cells (SC) from untreated CD2F1 mice; in peritoneal exudate cells and SC activated in vivo by injection of maleic anhydride divinyl ether 1,2-copolymer (MVE-2) or inactivated Candida albicans (CA); in lymphokine-activated killer (LAK) activity generated in vitro from splenocytes cultured with rhIL-2 and in allo-specific cytotoxic lymphocyte-mediated lysis generated in vitro. A significant inhibition of cytotoxic activity of all types of effector cells after 30 min incubation was already induced by OM at 1 x 10(-3) M concentration, after 1 h incubation at 5 x 10(-4) M and after 4 h incubation at 1 x 10(-4) M OM. Complete inhibition of lytic activity was obtained after 4 h incubation of effector cells with 1 x 10(-3) M OM. No inhibitory effect was observed at 5 x 10(-5) M OM concentration. Indomethacin did not abrogate the OM inhibitory effect on NK/LAK activity, suggesting that prostaglandins are not involved in the process leading to suppression of cytocidal activity. When effector cells were incubated with OM in presence of rhIL-2 (500 U/ml), the cytokine failed to antagonize the inhibitory effect of the drug. On the contrary, if OM pretreated cells were incubated with rhIL-2 for a further 18 h after drug removal, this cytokine was able to restore NK activity, but only when NK inhibition was incomplete. These results demonstrate for the first time that in vitro OM causes a rapid, strong effect on various types of cytotoxic lymphocytes ranging from cytotoxicity inhibition to irreversible cell damage.

Animals↗

PubMed1996

In vivo transgene activation from an HSV-based gene therapy vector by GAL4:vp16.

Herpes simplex virus type 1 (HSV-1) has many attributes which make it attractive as a base for the development of vectors for the delivery of transgenes to the nervous system. In this report we describe the adaptation of the bipartite GAL4:VP16 transactivation system to replication-deficient HSV vectors. We demonstrate that the recombinant transactivator GAL4:VP16 produced from a replication-deficient HSV vector is capable of activating transcription of a reporter gene using a synthetic promoter consisting of GAL4 binding sites and the TATA box of the adenovirus E1b gene. Activation by vector produced GAL:VP16 was demonstrated with the recombinant promoter/reporter gene cassette in the infected cell chromosome, in the genome of a second virus infecting the same cells and with a single vector engineered to produce both GAL4:VP16 transactivator and to contain a recombinant promoter/reporter gene cassette. Furthermore, the double recombinant virus also produced the reporter gene product in neurons after direct intracranial inoculation into rat hippocampus. This system may be used to extend and improve promoter function in HSV gene transfer vectors in vivo.

Animals↗

PubMed1995

Cytokine response to inactivated Candida albicans in mice.

Inactivated Candida albicans (CA) cells induce strong activation of natural cytotoxic effectors in mice. In the present study we examined the expression of cytokine genes involved in the immune response to CA. It has been reported that differential cytokine production by natural immune cells is important for regulating the development of specific TH response. Northern blot analysis was performed on peritoneal exudate cells (PEC) recovered from CD2F1 mice injected ip with five doses of CA (CA-5d, on Days -14, -10, -7, -3, 0 with respect to the in vitro assays at 2, 24, and 72 hr) or from mice injected ip with four doses of CA (CA-4d, on Days -14, -10, -7, -3 with respect to the in vitro assay on Day 0). On Day 0, before the fifth CA injection, PEC expressed a high level of IL-2 and a low level of IL-1 beta mRNAs while genes coding for IL-4, IL-5, IL-6, IL-10, IL-12, TNF alpha, and IFN gamma were not expressed and there was a high level of NK activity. Two hours after CA-5d a high level of IFN gamma and a low level of IL-10 mRNAs were already evident, while IL-2 and much more IL-1 beta had greatly increased. IL-6, TNF alpha, and IL-2R alpha chain mRNAs were also detectable, whereas IL-4, IL-5, and IL-12 were not expressed. IL-12 mRNA was also absent in earlier stages of the CA sensitization. Both cellularity and NK activity of peritoneal exudate had increased with respect to Day 0. At 24 hr whereas IL-2 mRNA remained high, both IL-1 beta and IFN gamma mRNAs expression had decreased. Expression of other cytokines was no longer detectable but NK activity remained high and a significant LAK activity was also induced. After 72 hr, while the IL-2 mRNA level and NK activity were still high the IL-1 beta mRNA expression had further decreased. These results indicate that CA induces a predominant production of IFN gamma and IL-2, cytokines involved in the development of TH1 response but it is unable to induce IL-12. This secondary pathway, without IL-12 involvement in the development of TH1 response, is probably the result of the ability of IL-2, IL-1 beta, and TNF alpha to synergize in inducing IFN gamma synthesis by NK cells.

Animals↗

PubMed1995

Cardiovascular and organ responses and adaptation responses to hypogravity in an experimental animal model.

The head-down suspension (i.e. antiorthostatic hypokinesia) rat is used to simulate weightlessness. However, little is known about cardiovascular and organ adaptation responses which, over a long time, can become pathologically significant. The purpose of this study was therefore to evaluate regional changes in the hematology parameters. Endotheline-1 (ET-1) concentration and urinary excretion of N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30) (NAG) in an experimental antiorthostatic rat model. The data indicate significant variations in the plasma ET-1 level in time, in the superior and inferior cava vessel blood of animals maintained for 10 days in hypogravity with respect to controls. These changes do not seem to be due to hemoconcentration. The increase in urinary NAG was observed during the first 24h of experiment, indicating renal stress, probably due to adverse blood flow variations within the organ. We conclude that the plasma ET-1 level changes could be responsible, overall for the blood flow variations in the kidney and renal stress could be the consequence of extended antiorthostatic hypokinesia. The ET-1 behaviour and urinary NAG excretion in rats exposed to antiorthostatic hypokinetic hydynamia offer possibilities for understanding if these changes might be reversible or when they become pathological. This could give some relevant information about the effects of prolonged hypogravity during the space voyage.

Acetylglucosaminidase↗

PubMed1995

Local and systemic immune response to inactivated Candida albicans in mice.

To improve our understanding of the role natural-immunity cells play in regulating the immune response to Candida albicans (CA) we compared local versus systemic effects of intraperitoneal inoculations with inactivated CA cells in mice. Peritoneal exudate cells (PECs) and spleen cells (SCs) were recovered from CD2F1 mice after 5 intraperitoneal CA injections (2 x 10(7) cells/mouse on days -14, -10, -7, -3 and 0 (CA-5d) with respect to in vitro assays performed at 2 h, 24 h, 3 days and 5 days). Northern blot analysis revealed that 2 h after CA-5d, PECs expressed a high level of IL-2, IFN-gamma, IL-1 beta and a low level of IL-10 and TNF-alpha mRNAs, while IL-4 and IL-5 mRNAs were absent, suggesting the development of TH1 subset. At 24 h, while IL-2 mRNA remained high, IL-1 beta and IFN-gamma expression had decreased and IL-10 and TNF-alpha mRNAs were no longer detectable. Instead, in spleens of CA-treated mice, examined up to 5 days after CA-5d, only IL-2 and IL-1 beta mRNAs were detectable, but the expression level was similar to that of untreated control mice. CA-5d induced a high level of natural-killer (NK)/lymphokine-activated-killer (LAK) activity in the peritoneal cavity but did not affect spleen NK activity. After CA-5d, the proliferative response of PECs to mitogens and CA antigens was also different from that of SCs. Unfractionated PECs were unable to proliferate in response to concanavalin A (Con A), IL-2, CA cells and CA cell wall mannoprotein, but after removal of the nylon-wool-adherent fraction, the nonadherent peritoneal cells (Nad-PECs) showed a significant proliferative response to mitogens. After depletion of NK cells by anti-asialo-GM1 antibody plus complement, the proliferative response of Nad-PECs to Con A and CA increased further. Contrary to the PEC response, unfractionated SCs from the same animals responded very well to mitogens and CA antigens and the proliferative response was significantly higher compared to that of SC from control mice. In conclusion, these results cast some light on the mechanisms by which NK cells and macrophages regulated the development of the local specific response to CA: activated NK cells, by producing IFN-gamma, favor the development of TH1 subset, while suppressor macrophages keep proliferation of T lymphocytes under control because of the presence of highly activated NK cells.

Animals↗

PubMed1994

Induction and persistence in vivo of NK/LAK activity by a mannoprotein component of Candida albicans cell wall.

In a previous study we demonstrated that NK/LAK effectors are quickly induced in the peritoneal cavity of CD2F1 mice by a booster dose with inactivated Candida albicans (CA) cells or by the purified cell wall mannoprotein (MP), for a long time after CA sensitization. In this study we investigated the immunologic nature and kinetics of early events of the booster phenomenon. Intraperitoneal inoculation of CA in CD2F1 mice, 30 days after pretreatment with five doses of CA (2 x 10(7) cells/mouse) over a 2-week period (CA-5d treatment), elicited a very rapid recruitment of asialo GM1+ cells, L3T4+ cells, and Ly 2+ cells. Asialo GM1+ cells and Ly 2+ cells reached a maximum number 12 hr after the booster dose, while L3T4+ cells reached the maximum after 24 hr. The number of L3T4+ cells was about twofold greater than Ly 2+ cells at all times tested. A similar kinetic pattern was found after MP booster. In C57BL/6 mice we confirmed that CA and MP boosters induced LGL which express a NK antigen, detected by 3A4 mAb, and the activation marker CD25. The peak of non-MHC-restricted PEC cytotoxicity, which was reached 24 hr after MP or CA booster, did not correspond to the time (12 hr) for maximum number increase of asialo GM1+ cells and 3A4+ cells. Two hours after CA or MP booster in PEC there was a rapid and strong increase of IL-2 mRNA expression, which persisted at a high level 24 hr after booster. In CA-5d-pretreated mice, a persistent NK/LAK-like activity in the peritoneal cavity can be maintained by boosters with MP administered every 3 days. Such treatment, which we performed up to 15 days after CA sensitization, rendered the mice more responsive to further MP boosters. Effects of CA were not restricted to the peritoneal compartment because (a) there was a rebound of splenic NK activity about 10 days after CA-5d treatment by ip route and (b) CA given by iv route significantly increased splenic NK activity up to 15-20 days after CA-5d treatment. Recombinant human interleukin 2 (rhIL-2), given ip to mice (1000 U/mouse) in combination with CA during CA-5d treatment and with MP in the booster, strongly increased the level of peritoneal NK/LAK activity and PEC cellularity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1994

Antibody-independent protection in mice against type Ia group B streptococcus lethal infection.

There is ample evidence that protection against group B streptococcal (GBS) disease, both in experimental animals and in humans, is related to the presence of specific antibodies and complement. However, until now the possibility of increasing resistance to GBS infection by potentiating natural cell-mediated immunity in the host, has not been explored. In this study we examine the effect of administering in vivo MVE-2 (a polymer fraction of 1,2-co-polymer of divinyl ether and maleic anhydride) and inactivated Candida albicans (CA) cells on mouse resistance to the reference strain type Ia 090 GBS (GBS-090) lethal infection. MVE-2 and CA, respectively a synthetic and a microbial biological response modifier (BRM), are strong inducers and activators of natural resistance effectors, such as natural killer (NK) cells, macrophages and polymorphonuclear cells (PMN). The results showed that MVE-2 protected 100% CD-1 mice from a systemic lethal challenge with GBS-090 (5 x 10(3) microorganisms/mouse) when administered 3 days before infection at dose of 50 mg kg-1. CA treatment, in five doses (CA-5d) over 14 days protected 100% mice when administered at 2 x 10(7) cells/mouse and when the last CA injection was given 1 day before the GBS-090 challenge. Instead, when the GBS-090 challenge was performed by intraperitoneal route, protection was obtained with CA-5d treatment but not with MVE-2. The possibility that MVE-2 or CA stimulated a rapid production of specific antibodies against GBS-090 infection was excluded by the ELISA assay. Evidence exists that NK cells do not play a primary role as effectors in the MVE-2 and CA conferred protection since the strong reduction in NK activity, due to in vivo administration of anti-asialo GM1 antibodies before GBS-090 infection, did not influence the BRM-induced protection. Besides, high NK activity levels, induced by in vivo rhIL-2 administration, did not protect the mice against GBS-090 infection. Both studies on in vivo clearance and in vitro microbicidal activity, showed that, after 1 h, immunopotentiated effectors were unable to kill GBS-090, but were highly effective against GBS type VI. These results seem to indicate that intracellular GBS-090 killing is a slow process requiring more than 1 h. This study demonstrates that it is possible to increase resistance to GBS-090 lethal infection by BRMs, by potentiating the antibody-independent microbicidal activity of the phagocytes.

Animals↗