Biomedical subjects

P Mastroeni

Publications and source records attributed to P Mastroeni.

At least 37 records · Page 2Linked to original sources

PubMed1999

Granulocyte-macrophage colony stimulating factor modulates the production of TNF alpha by differentiated U937 cells infected with Leishmania major.

In this work, the production of tumor necrosis factor alpha (TNF alpha) during interaction of human phagocytes with the intracellular parasite Leishmania major was further investigated. The human monocytic cell line U937, differentiated with a combination of 1 alpha, 25 dihydroxyvitamin D3 (VD) and retinoic acid (RA), or with granulocyte macrophage colony stimulating factor (GM-CSF) was used. Differentiated U937 cells were infected with Leishmania major promastigotes, and TNF alpha was assayed in cell culture supernatants. It was found that the cytokine was produced only by U937 cells differentiated with VD/RA and further incubated with GM-CSF and LPS or interferon gamma (IFN gamma). L. major induced TNF alpha production only in the presence of GM-CSF. No direct relationship was found, however, between production of TNF alpha and resistance of differentiated U937 cells to infection with L. major.

Adjuvants, Immunologic↗

PubMed1998

Interleukin-12 is required for control of the growth of attenuated aromatic-compound-dependent salmonellae in BALB/c mice: role of gamma interferon and macrophage activation.

The attenuated S. typhimurium SL3261 (aroA) strain causes mild infections in BALB/c mice. We were able to exacerbate the disease by administering anti-interleukin-12 (IL-12) antibodies, resulting in bacterial counts in the spleens and livers of anti-IL-12-treated mice that were 10- to 100-fold higher than the ones normally observed in premortem mice; yet the animals showed only mild signs of illness. Nevertheless, they eventually died of a slow, progressive disease. Mice infected with salmonellae become hypersusceptible to endotoxin. We found that IL-12 neutralization prevented the death of infected mice following subcutaneous injection of lipopolysaccharide. Granulomatous lesions developed in the spleens and livers of control animals, as opposed to a widespread infiltration of mononuclear cells seen in the organs of anti-IL-12-treated mice. In the latter (heavily infected), salmonellae were seen within mononuclear cells, indicating an impairment of the bactericidal or bacteriostatic ability of the phagocytes in the absence of biologically active IL-12. Gamma interferon (IFN-gamma) levels were reduced in the sera and tissue homogenates from anti-IL-12-treated mice compared to those in control animals. Furthermore, fluorescence-activated cell sorter analysis on spleen cells showed that IL-12 neutralization impaired the upregulation of I-Ad/I-Ed antigens on macrophages from infected mice. Inducible nitric oxide synthase and IFN-gamma mRNA production was down-regulated in anti-IL-12-treated mice, which also showed an increased production of IL-10 mRNA and a decrease in nitric oxide synthase activity in the tissues. Administration of recombinant IFN-gamma to anti-IL-12-treated mice was able to restore host resistance, granuloma formation, and expression of major histocompatibility complex class II antigens in F4/80(+) and CD11b+ spleen cells.

Animals↗

PubMed1998

Comparative effect of gentamicin and pefloxacin treatment on the late stages of mouse typhoid.

The present study compares the ability of gentamicin and pefloxacin to eradicate a Salmonella infection in BALB/c mice when the treatment is instituted in the late stages of the infection. The results indicate that pefloxacin is highly effective in the treatment of mouse typhoid even when the therapy is instituted after the suppression of bacterial growth in the reticuloendothelial system (RES). Conversely, gentamicin treatment only reduced the bacterial load in the RES of infected mice, but neither induced the clearance of the organisms from the RES, nor prevented the resurgence of bacterial growth. Even when using gentamicin at a high dosage, bacterial clearance could not be accomplished.

Animals↗

PubMed1997

Salmonella typhimurium infections in mice deficient in interleukin-4 production: role of IL-4 in infection-associated pathology.

Mice harboring mutations in the IL-4 gene (IL-4(-/-)) were infected with a range of Salmonella typhimurium HWSH derivatives using different routes of infection. Compared with IL-4(+/+) mice, IL-4(-/-) mice exhibited a delayed time to death following infection with wild-type S. typhimurium HWSH. Groups of IL-4(+/+) mice infected with S. typhimurium HWSH purE, a less virulent derivative, showed sporadic deaths and harbored micro- or macroabscesses in their tissues, particularly associated with the liver. However, IL-4(-/-) mice infected with similar doses of S. typhimurium HWSH purE bacteria were resistant to killing and failed to develop detectable abscesses. Abscess formation in IL-4(-/-) mice could be induced by i.v. administration of rIL-4 during the S. typhimurium HWSH purE infection. The immune response in both IL-4(-/-) and IL-4(+/+) mice was of the Th1-type. Viable salmonella bacteria could be found associated with abscesses. Both IL-4(-/-) and IL-4(+/+) mice were resistant to killing by S. typhimurium aroA.

Animals↗

PubMed1997

Correlates of protection induced by live Aro- Salmonella typhimurium vaccines in the murine typhoid model.

Live attenuated salmonella vaccines generally confer better protection than killed vaccines. The immune responses in BALB/c mice elicited by immunization with a live attenuated Aro Salmonella typhimurium vaccine given orally, intravenously or subcutaneously were compared with those elicited by killed whole-cell vaccines (acetone or heat-treated) given subcutaneously. Live vaccines given by all routes elicited higher interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) responses in spleen cells against an alkali-treated whole-cell salmonella lysate than did killed vaccines. Live and killed vaccines elicited high total antibody levels to smooth lipopolysaccharide (LPS) (enzyme-linked immunosorbent assay), but all live vaccine regimes elicited higher IgG2a, suggesting a Th1 response. Oral and intravenous vaccination with live organisms elicited IgA against smooth LPS which subcutaneous vaccination with live or killed salmonellae failed to evoke. Western blots using rough whole-cell lysates showed that all vaccines elicited a varied anti-protein response; however, all groups immunized with live organisms recognized three unidentified bands of MW 52,000, 46,000 and 18,000 which were consistently absent in groups immunized with killed organisms. The results indicate that immunization with live aroA salmonellae elicited a Th1 type of response, including bystander T-cell help to LPS, and a response to proteins not seen in mice that received killed vaccines.

Administration, Oral↗

PubMed1997

Salmonella typhimurium aroA, htrA, and aroD htrA mutants cause progressive infections in athymic (nu/nu) BALB/c mice.

Athymic (nu/nu) BALB/c mice and their euthymic (nu/+) littermates were inoculated intravenously with live attenuated vaccine strains of Salmonella typhimurium. All strains caused progressive infections in the athymic mice but not in their euthymic littermates. Athymic mice given strain SL3261, an aroA derivative of SL1344, in doses between log 4.7 and 5.7 CFU were all severely ill and were killed by weeks 4 to 5. Athymic mice given log 4.7 CFU of a derivative of S. typhimurium C5 carrying a mutation in htrA, encoding a stress protein, were ill and were killed by week 7 in one experiment but survived to week 13 in another. Athymic mice given log 4.6 CFU of a C5 aroD htrA double mutant were ill and were killed at week 7. Athymic mice given SL3261 had high bacterial counts in the reticuloendothelial system at 4 weeks. Athymic mice given SL3261 or C5 htrA made immunoglobulin G3 (IgG3) (and to a lesser extent IgM) antibody to lipopolysaccharide (LPS), whereas euthymic mice made IgM, IgG1, IgG2a, IgG2b, and IgG3 anti-LPS antibodies. The results indicate that both aroA and htrA strains will produce slow, progressively lethal infections in athymic mice, that the htrA strain is more attenuated than the aroA strain as measured by time to death in this model, and that IgG3 anti-LPS antibody alone cannot suppress the progress of infections by very attenuated strains in athymic mice.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗

PubMed1996

Protection against oral challenge three months after i.v. immunization of BALB/c mice with live Aro Salmonella typhimurium and Salmonella enteritidis vaccines is serotype (species)-dependent and only partially determined by the main LPS O antigen.

The role of the main LPS O antigen in the specificity of protection as mediated by systemic mechanisms following immunization with live attenuated Aro Salmonella vaccines was studied in mice. Innately Salmonella-susceptible (Itys) BALB/c mice were immunized intravenously with a single dose of either Salmonella typhimurium SL3261 aroA (LPS O4,5,12) or Salmonella enteritidis Se795aroA (LPS O1,9,12), and challenged orally 2-3 months later with either S. typhimurium C5 or S. enteritidis Thirsk. Nearly isogenic transductants of the two challenge strains expressing either their own LPS or that of the other serotype (S. typhimurium C5 O4 or O9, and S. enteritidis Thirsk O9 or O4) were also used. Both vaccines conferred similar high protection against the virulent strain of the homologous serotype expressing its own LPS. There was no protection against the heterologous serotype expressing its own LPS. However, when vaccinated mice were challenged with either the same serotype as the vaccine but expressing the heterologous LPS, or with the heterologous serotype expressing the LPS of the vaccine, protection was always lower than protection against the fully homologous serotype. Anti-smooth LPS antibodies showed higher titres against the homologous LPS, but with significant crossreactivity with the heterologous LPS. Antibodies to O-rough S. typhimurium and S. enteritidis LPS were present following immunization with either of the two vaccine strains. The LPS alone cannot fully account for the specificity of protection in this model; other (protein) antigens may be responsible. It remains to be seen whether there is a T-cell mediated component to the specificity of protection conferred by live Salmonella vaccines.

Animals↗

PubMed1996

Effect of interleukin 12 neutralization on host resistance and gamma interferon production in mouse typhoid.

Innately resistant (Ityr) A/J mice infected with the virulent Salmonella typhimurium C5 strain suppress the early exponential bacterial growth in the reticuloendothelial system toward the end of the first week of infection, with spleen and liver bacterial counts reaching a plateau phase. In vivo administration of neutralizing anti-interleukin-12 (IL-12) antibodies did not affect early bacterial growth in the tissues (days 1 to 3) but impaired the establishment of the plateau, with higher spleen and liver counts by day 7 of the infection in anti-IL-12 treated mice than in untreated controls. Gamma interferon (IFN-gamma) was detectable in the sera and spleen homogenates of both control and anti-IL-12-treated mice on days 3 and 7 of the infection. Noticeably, IFN-gamma levels were significantly lower in anti-IL-12 treated mice than in control animals. Splenocytes from uninfected A/J mice released IFN-gamma in response to concanavalin A (ConA) or to S. typhimurium C5. In vitro IL-12 neutralization dramatically impaired the IFN-gamma response to S. typhimurium but not to ConA. Splenocytes harvested from infected anti-IL-12 treated mice on day 7 of the infection produced significantly lower amounts of IFN-gamma upon in vitro stimulation with ConA and with a Salmonella protein-rich extract than did cells from similarly infected untreated control animals. Spleen cells from infected mice showed lower proliferative (mitogenic) responses to ConA and to a Salmonella soluble extract than did cells from uninfected mice. In vivo anti-IL-12 treatment significantly restored the ability of splenocytes from infected mice to proliferate in response to the antigens and ConA. In vivo neutralization of IL-12n in innately susceptible BALB/c mice ((ItyS)) immunized with a live attenuated aromatic-dependent Salmonella vaccine reduced host resistance to virulent oral challenge with S. typhimurium C5. Thus, in primary Salmonella infections, IL-12 mediates the suppression of growth of virulent salmonellae in the reticuloendothelial system, positively modulates IFN-gamma production, and is involved in the immunosuppression which accompanies the acute stages of the disease. IL-12 also contributes to host resistance to virulent organisms in secondary infections.

Animals↗

PubMed1995

Morphological modifications of the choroid plexus in a rodent model of acute ventriculitis induced by gram-negative liquoral sepsis. Possible implications in the pathophysiology of hypersecretory hydrocephalus.

Gram-negative bacterial infections of the central nervous system are generally associated with high morbidity and mortality rates. In patients with ventriculitis induced by gram-negative liquoral sepsis, a reduction in cerebrospinal fluid formation has been reported, suggesting that gram-negative ventriculitis is able per se to alter the normal functioning of the choroid plexus. The aim of the present study was to analyse, for the first time in the rat, the effects of acute ventriculitis on the ultrastructure of the choroid plexus. A simple and inexpensive experimental model of acute ventriculitis was developed: we injected into the cisterna magna of rats 10(3) CFU of live Escherichia coli, inducing septic ventriculitis without major neurological deficits. Histological examinations of rodent choroid plexus 24 h after the injection revealed patches of altered epithelium, with swollen and vacuolated ependymal cells associated with leukocyte infiltration. Electron microscopy demonstrated a reduced number of microvilli and flattening of the epithelial surface. These results (a) indicate that gram-negative septic ventriculitis is able to induce visible ultrastructural alterations of the choroid plexus which (b) are consistent with a picture of marked reduction of the functioning epithelial choroid plexus surface, and (c) highlight the potential usefulness of our rodent acute ventriculitis model for developing treatment modalities.

Acute Disease↗

PubMed1995

Entry of Listeria monocytogenes into hepatocytes requires expression of inIB, a surface protein of the internalin multigene family.

The intracellular bacterium Listeria monocytogenes can invade several types of normally non-phagocytic cells. Entry into cultured epithelial cells requires the expression of inIA, the first gene of an operon, comprising two genes: inIA, which encodes internalin, an 800-amino-acid protein, and inIB, which encodes a 630-amino-acid protein. Several genes homologous to inIA are detected in the genome of L. monocytogenes; InIB is one of them. We have assessed the role of inIB in invasiveness of L. monocytogenes by constructing isogenic chromosomal deletion mutants in the inIAB locus. Our findings indicate that: i) inIB is required for entry of L. monocytogenes into hepatocytes, but not into intestinal epithelial cells; ii) inIB encodes a surface protein; iii) internalin plays a role for entry into some hepatocyte cell lines. These results provide the first insight into the cell tropism displayed by L. monocytogenes.

Amino Acid Sequence↗

PubMed1995

Comparative convulsant potencies of two carbapenem derivatives in C57 and DBA/2 mice.

The behavioural and convulsant effects of imipenem and meropenem were studied after intraperitoneal administration in DBA/2 mice, a strain genetically susceptible to sound-induced seizure, and in C57 mice, a strain not prone to seizure. DBA/2 mice were more susceptible than C57 mice to seizures induced by imipenem-cilastatin or meropenem. Imipenem was also 1.9 times more potent than meropenem in inducing clonus in DBA/2 mice. To investigate the possibility that the seizure-inducing activity of imipenem might be due to a probenecid-like effect of cilastatin, animals were treated with imipenem alone. No significant differences were observed between imipenem-cilastatin and imipenem-treated animals. Thus, it is reasonable to exclude a probenecid-like effect of cilastatin. Although the main mechanism for seizure-like activity of imipenem cannot be easily determined, we believe that several mechanisms may be involved. An increased excitation of the central nervous system (CNS) by inhibition of GABA binding to receptors and a slow clearance of imipenem from the CNS may be postulated. Cilastatin did not induce seizures. In addition, meropenem, a compound structurally related to imipenem, showed weak or no convulsant effects.

Animals↗

PubMed1995

Effect of anti-tumor necrosis factor alpha antibodies on histopathology of primary Salmonella infections.

We reported that administration of anti-tumor necrosis factor alpha (anti-TNF-alpha) antibodies exacerbates the course of a Salmonella infection in both susceptible and resistant mice by preventing the suppression of bacterial growth in the reticuloendothelial system. In the present study, we evaluated the effect of in vivo neutralization of TNF-alpha on the histopathology of primary Salmonella infections. We show that in primary infections, the suppression of bacterial growth in the reticuloendothelial system coincides with granuloma formation in the spleen and liver. Administration of anti-TNF-alpha globulins on day -1 of salmonellosis affected neither the histological picture nor the course of the infection in the early stages of the disease (days 1 to 3), with splenic and hepatic lesions consisting mainly of polymorphonuclear leukocytes (PMNs); conversely, later in infection (days 3 to 7), the treatment inhibited the formation of granulomas. When the anti-TNF-alpha treatment was started well after the suppression of bacterial growth in the reticuloendothelial system and the formation of granulomatous lesions in the spleen and liver, a prompt relapse of the infection and regression of already established granulomas were seen. In anti-TNF-alpha-treated mice, salmonellae were found inside macrophages and PMNs and extracellularly in the necrotic tissue of the spleen, while in the liver the organisms were seen mainly in inflammatory mononuclear cells, resident Kupffer cells, and hepatocytes and occasionally in the extracellular compartment within necrotic lesions. The bacteria appeared most often in clusters, being morphologically intact when in the extracellular space or within hepatocytes, while undergoing various degrees of degeneration when inside phagocytes. The results suggest that TNF-alpha is required for granuloma formation in salmonellosis and that its neutralization does not completely abrogate the bactericidal activity of macrophages and PMNs. Salmonellae were observed to grow within both hepatocytes and phagocytes but were killed only in the latter.

Animals↗

PubMed1994

Toxicity of lipopolysaccharide and of soluble extracts of Salmonella typhimurium in mice immunized with a live attenuated aroA salmonella vaccine.

Mice immunized intravenously 10 days earlier (but not those immunized 2 months earlier) with an attenuated Salmonella typhimurium SL3261 aroA live vaccine and tested for delayed-type hypersensitivity by injection of crude Salmonella extracts in the footpad can die within 24 to 48 h of an unexplained allergic reaction. The lethal reaction could be prevented by prior administration of anti-tumor necrosis factor alpha serum. Injection of lipopolysaccharide (LPS) (either purified phenol-water-extracted [Westphal] LPS or protein-rich trichloracetic acid-extracted [Boivin] LPS) was also lethal for mice immunized 10 days before. An LPS-rich crude Salmonella extract was more toxic than one which contained less LPS, suggesting that LPS may have been involved in the lethal reactions to crude antigens. Mild alkaline hydrolysis removes O-linked acyl groups from lipid A and eliminates many toxic effects of LPS; however, both Boivin LPS and Westphal LPS remained toxic for immunized mice after alkaline hydrolysis. In contrast, alkaline hydrolysis of crude whole Salmonella extracts (which caused marked protein degradation) reduced the lethal toxicity of the extracts, especially for an LPS-rich preparation. Mice immunized orally with the live vaccine did not show hypersensitivity to either LPS or crude extracts. The results suggest that the lethal reaction to crude Salmonella antigens in mice immunized 10 days earlier is complex, that tumor necrosis factor alpha is involved, and that allergic reactions to crude antigens (but not to LPS alone) can be reduced by mild alkaline hydrolysis.

Animals↗

PubMed1993

Delayed (footpad) hypersensitivity and Arthus reactivity using protein-rich antigens and LPS in mice immunized with live attenuated aroA Salmonella vaccines.

Footpad reactions to protein-rich salmonella extracts and lipopolysaccharide (LPS) were studied in BALB/c mice 2 and 8 months after immunization with the Salmonella typhimurium SL3261 aroA live vaccine. T-cell depletion in vivo and adoptive serum transfer showed that protein-rich antigens induced T-cell dependent delayed hypersensitivity reactions, whereas LPS only elicited Arthus reactions. The footpad reactions to crude protein extracts were not always T-cell mediated, but depended on the nature and the dose of the antigen. Selective depletion of CD4+ T cells alone had a greater effect than depletion of CD8+ T cells alone, but neither was as marked as simultaneous depletion of both CD4+ and CD8+ T cells, which abolished the delayed type hypersensitivity (DTH) response. Crude protein-rich extracts subjected to alkaline hydrolysis (which removes some ester-linked fatty acids and causes disaggregation of LPS resulting in decreased toxicity while conserving O-specificity) still gave positive T-cell dependent reactions, but with reduced T-cell independent reactivity. Purified phenol-water LPS (2.5 micrograms) produced Arthus reactivity which could be confused with DTH. LPS induced positive reactions which still occurred in T-cell depleted mice and were transferable by immune serum. Arthus reactions did not occur when using alkali-treated LPS, which showed reduced complement fixation in vitro when using serum from immunized mice. The results indicate that footpad testing using salmonella antigens containing LPS elicit DTH but can also produce toxic reactions, some of which are T-cell independent and not necessarily a true measure of DTH. Arthus reactivity to LPS can be confused with DTH. Alkaline hydrolysis of the antigens can eliminate non-specific reactogenicity while retaining the ability of the (protein-rich) antigen to elicit a true T-cell dependent footpad response, which requires the participation of both CD4+ and CD8+ T cells.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗

PubMed1993

Effect of late administration of anti-TNF alpha antibodies on a Salmonella infection in the mouse model.

The effect of late administration of anti-TNF alpha antibodies on the course of a Salmonella infection in mice was evaluated. Administration of anti-TNF alpha antiserum as late as day 5 after challenge enhanced a sublethal primary infection with the virulent Salmonella typhimurium C5 in innately resistant (Ityr) A/J mice by preventing the suppression of exponential bacterial growth in the reticuloendothelial system (RES) (plateau phase). When the anti-TNF alpha treatment was started well after the establishment of the plateau (day 7) a prompt relapse of the infection occurred, with the rapid resurgence of bacterial growth in the reticuloendothelial system leading to the death of the animals. In contrast, late administration of the antiserum did not affect the clearance from the tissues of an avirulent temperature-sensitive mutant of S. typhimurium C5 (C5TS). Innately susceptible (Itys) BALB/c mice immunized with the SL3261 aroA live vaccine acquire solid long-lasting protection from oral challenge with the virulent C5 strain, suppressing growth of the challenge in the RES. Administration of anti-TNF alpha antibodies on day 8 of a secondary oral infection with strain C5 abrogated vaccine-induced protection, with a progressive increase of bacterial numbers in the RES leading to the death of the animals. The results indicate that TNF alpha is constantly required for the control of virulent salmonellae in the RES, both in a sublethal primary infection in innately resistant mice and also in a secondary infection in innately susceptible mice immunized with a live vaccine. TNF alpha may not be essential for bacterial clearance of avirulent organisms from the tissues.

Animals↗

PubMed1993

Adoptive transfer of immunity to oral challenge with virulent salmonellae in innately susceptible BALB/c mice requires both immune serum and T cells.

The mechanisms of immunity to salmonellae conferred by immunization with live vaccines were studied by adoptive transfer using the mouse-virulent strain Salmonella typhimurium C5 and innately susceptible BALB/c (ltys) mice. This organism cannot establish a sublethal infection in naive BALB/c mice. Animals immunized 2 to 3 months earlier with the S. typhimurium SL3261 aroA live vaccine were used as donors of serum, spleen cells, and mesenteric lymph node cells for naive recipients which were challenged orally with the virulent C5 strain. Simultaneous transfer of both immune serum and immune cells was necessary for protection. Simultaneously depleting the donors of CD4+ and CD8+ T cells by administration of antisera in vivo prior to cell harvesting showed that T cells were necessary for protection. The results demonstrate that both antibody and T cells are required for recall of immunity to oral challenge with virulent salmonellae in innately susceptible mice and suggest that the ability to elicit opsonizing antibody in addition to cell-mediated immunity is important for optimal protection induced by salmonella vaccines.

Animals↗

PubMed1992

Role of T cells, TNF alpha and IFN gamma in recall of immunity to oral challenge with virulent salmonellae in mice vaccinated with live attenuated aro- Salmonella vaccines.

The SL3261 Salmonella typhimurium aroA live vaccine strain confers solid protection against oral challenge with virulent salmonellae, immunity persisting long after the vaccine has been cleared from the tissues. BALB/c mice immunized with SL3261 and later subjected to in vivo depletion of both CD4+ and CD8+ T cells had impaired recall of immunity to oral challenge with the virulent S. typhimurium C5, with increased mortality and higher bacterial loads in the reticuloendothelial system (RES). Selective depletion of CD4+ cells alone significantly impaired resistance both 8 and 14 weeks after vaccination as determined by estimation of bacterial numbers in organ homogenates. Depletion of CD8+ cells alone had less effect on immunity when performed at 8 weeks than at 14 weeks after immunization. Administration of anti-IFN gamma or anti-TNF alpha antibodies also impaired recall of immunity, exacerbating a secondary infection in vaccinated mice. Challenge of T cell-depleted immune mice with virulent salmonellae caused hepatosplenomegaly with minute grossly visible focal lesions, and a marked increase in the number and severity of necrotic foci in spleen, liver and lymph nodes. A widespread mononuclear cell infiltrate was present. The histopathology in anti-IFN gamma-treated mice was qualitatively similar to that seen in T-cell depleted mice. In contrast, in the anti-TNF alpha-treated mice splenomegaly was much less than in T cell-depleted mice. Granulomas were absent, no mononuclear infiltration was observed and there was severe necrosis; the lesions appeared similar to or worse than those seen in naïve mice. Surprisingly, IFN gamma was detectable in sera of both controls and T cell-depleted mice on day 8 of the secondary infection, as well as in sera of anti-TNF alpha-treated mice on day 6 of infection. The results indicate that T cells, IFN gamma and TNF alpha are all important in the specific recall of immunity to virulent salmonellae conferred by immunization with live vaccines, with the effect of T cell and IFN gamma depletion (marked macrophage infiltration) being qualitatively very different from that of TNF alpha neutralization (no mononuclear infiltrate or granuloma formation).

Animals↗

PubMed1992

Proliferative and T-cell specific interleukin (IL-2/IL-4) production responses in spleen cells from mice vaccinated with aroA live attenuated Salmonella vaccines.

T-cell responses were studied in mice immunized with the Salmonella typhimurium aroA SL3261 live attenuated vaccine strain. T-cell responses in the spleen, both in whole cell populations and in nylon wool non-adherent (T-cell enriched) cells, were studied in vitro as proliferation by incorporation of tritiated thymidine and production of T-cell specific cytokines [IL-2 (interleukin-2)/IL-4]. Stimulating antigens included whole Salmonella lysates and purified lipopolysaccharide (LPS), both untreated and after alkaline hydrolysis to prevent the non-specific mitogenic effect of LPS. Strong proliferative responses were obtained with untreated whole cell extract and LPS, which were decreased by polymyxin B (PB). Alkaline detoxification of the antigens decreased the proliferative response of nylon-wool non-adherent populations to LPS, but greatly increased their response to the Salmonella extract. Surprisingly, PB also reduced proliferation to detoxified LPS. Little or no IL-2/IL-4 production was seen in response to LPS or purified polysaccharide antigens, while there was a strong IL-2/IL-4 response to whole cell lysate, again markedly increasing after alkaline treatment. The results suggest that the T-cell response elicited by immunization with live Salmonella aroA vaccines in mice recognizes antigens other than LPS determinants, and that estimation of T-cell responses to Salmonella antigens by proliferation alone may yield misleading results.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗