Regulation of cell-mediated immunity in leishmaniasis.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
F Y Liew
Publications and source records attributed to F Y Liew.
Biotechnology of vaccine development.
Explore the source record for details and available documents.
Antibody Formation↗
Anti-viral immunity induced by recombinant nucleoprotein of influenza A virus. III. Delivery of recombinant nucleoprotein to the immune system using attenuated Salmonella typhimurium as a live carrier.
A plasmid encoding the influenza nucleoprotein gene from A/NT/60/68 virus was transduced into the attenuated Salmonella typhimurium aroA- strain SL3261. The bacterial vector expressing the viral gene product was able to induce both humoral and cell-mediated immune responses to the nucleoprotein antigen. CD4+ virus-specific T cells capable of proliferation were readily induced and, in some circumstances, class II major histocompatibility complex (MHC)-restricted cytotoxicity was detected. However, virus-specific class I MHC-restricted cytotoxic T lymphocytes (CTL) were not detected after such immunization. Mice immunized orally with the nucleoprotein-expressing bacteria mounted a strong anti-viral antibody response and spleen cells from such mice proliferated specifically to virus challenge in vitro, producing interferon-gamma (IFN-gamma) and interleukin-2 (IL-2). Orally immunized mice showed significant protection from challenge infection with influenza virus if the mice were also boosted intranasally before infection.
Animals↗
Anti-viral immunity induced by recombinant nucleoprotein of influenza A virus. II. Protection from influenza infection and mechanism of protection.
Protection against influenza A virus infection in mice immunized with recombinant nucleoprotein (rNP) was studied. Nucleoprotein-immune mice were protected against a lethal challenge with A/Puerto Rico/8/34 (A/PR8) virus but showed considerable morbidity before recovery. Local boosting of the immune system with rNP by intranasal immunization improved the protection in NP-immune mice, and the decrease in morbidity after infection was reflected in accelerated clearance of virus from lungs. However, immune, boosted mice also rapidly cleared an antigenically unrelated influenza B virus from their lungs. Mice immunized with rNP precipitated with alhydrogel, that subsequently developed significant resistance to virus infection, failed to generate detectable levels of class I major histocompatibility complex (MHC)-restricted killer cells. Furthermore, B10.A(5R) mice that are non-responders for NP-specific class I killer cells could also be protected by immunization with rNP. In contrast, rNP-immunized mice developed strong proliferative T-cell responses to rNP. These data argue for an important role for helper T cells rather than virus-specific class I cytotoxic T cells in protection against influenza virus infection induced by rNP.
Animals↗
Interleukin-3 protects mice from acute herpes simplex virus infection.
Evidence presented here from kinetic studies of interleukin-3 (IL-3) production by spleen cells from adult mice infected subcutaneously with HSV-1 and stimulated with virus antigen in vitro shows that high levels of IL-3 were produced at the onset of the animal's recovery from the disease state. Injections of anti-IL-3 antibody into HSV-1-infected mice resulted in exacerbation of the disease. Primary mouse embryonic head cells grown in the presence of murine IL-3, when infected with HSV-1, showed a 1000-fold decrease in virus titre compared with untreated control cells. This inhibiting effect was reversed by anti-IL-3 and anti-IFN-alpha, beta and gamma antibodies. These data suggest that IL-3 plays a host-protective role against HSV infection and it does so probably by inducing brain cells to produce interferons which then inhibit virus replication.
Acute Disease↗
Tumour necrosis factor (TNF-alpha) in leishmaniasis. II. TNF-alpha-induced macrophage leishmanicidal activity is mediated by nitric oxide from L-arginine.
Peritoneal macrophages from CBA mice incubated with recombinant murine tumour necrosis factor (TNF-alpha) are effective in killing the protozoa parasite Leishmania major in vitro. The leishmanicidal activity is directly correlated with the level of nitrite (NO2-) in the culture supernatants. The killing of intracellular parasites can be completely inhibited by L-NG-monomethyl arginine (L-NMMA), a specific inhibitor of the L-arginine:nitric oxide (NO) pathway. The level of NO2-, which is also a measurement of NO production, in the culture supernatant of TNF-alpha-activated macrophages can be progressively decreased to basal level with increasing concentrations of L-NMMA, but not with its D-enantiomer, D-NMMA. These data demonstrate that NO is an important effector mechanism in the TNF-alpha-induced macrophage killing of intracellular protozoa.
Animals↗
Tumour necrosis factor (TNF alpha) in leishmaniasis. I. TNF alpha mediates host protection against cutaneous leishmaniasis.
Genetically resistant CBA mice developed significantly larger lesions to Leishmania major infection when they were injected with rabbit anti-tumour necrosis factor (TNF)-specific antibodies compared to control mice injected with normal rabbit immunoglobulin. BALB/c mice recovered from a previous infection following prophylactic sublethal irradiation also developed exacerbated lesions when treated with the anti-TNF antibody. Injection of TNF into the lesion of infected CBA mice significantly reduced the lesion development. Furthermore, TNF activates macrophages to kill Leishmania in vitro. These data demonstrate that TNF plays an important role in mediating host-protection against cutaneous leishmaniasis.
Animals↗
Identification and characterization of T helper epitopes in the nucleoprotein of influenza A virus.
By using a series of overlapping synthetic peptides that cover more than 95% of the amino acid sequence of nucleoprotein (NP) of influenza A/NT/60/68 virus, five Th cell epitopes in B10.S (H-2s), BALB/c (H-2d), CBA (H-2k), and B6 (H-2b) mice have been identified. The specificity of Th cell recognition of epitopes is largely dependent on the H-2 haplotype of the responding mouse strain. However, two out of the five Th epitopes defined could be recognized by mice of more than one haplotype, implying that the primary sequence of protein antigens could also influence the selection of dominant T cell epitopes by the immune system. Immunization of B10.S mice with peptide 260-283 generated strong Th cell response against type A influenza viruses. In the other three strains of mice tested, priming with helper peptides induced a stronger antipeptide than antiviral T cell response. However, the low responsiveness to virus in these mice could be partially overcome by immunization with a mixture of several helper peptides. The Th epitopes are defined by the ability of the peptides to stimulate class II MHC restricted CD4+ T cells to proliferate and to produce IL-2 in vitro. When compared with the known epitopes on NP recognised by class I restricted CD8+ cytotoxic T cells, it appears that Th and cytotoxic T cell epitopes are nonoverlapping. The AMPHI and Motifs methods were employed to analyze the sequence of NP and predict the potential dominant sites in the molecule. The predictions are compared with the experimental data obtained and the implications discussed.
Amino Acid Sequence↗
Enhancement of macrophage IL-1 production by Leishmania major infection in vitro and its inhibition by IFN-gamma.
Peritoneal cells from highly susceptible BALB/c mice were infected with Leishmania major and cultured for various times in vitro. The culture supernatants contained significant levels of IL-1 which were consistently higher than those in the cell cultures stimulated with an optimal concentration of LPS. This finding extends to a macrophage cell line, P388D1, and peritoneal exudate cells stimulated with starch in vivo. However, the level of IL-1 produced was significantly reduced when the cells were preincubated with a lymphokine preparation (supernatant of Con A-stimulated rat spleen cells). The level of IL-1 produced seems to be directly correlated with the degree of parasitization of the macrophages. A similar and dose-dependent reduction in IL-1 production by infected macrophages could also be obtained when the cells were preincubated with IFN-gamma. This finding is in direct contrast to that of visceral leishmaniasis in which peritoneal macrophages from BALB/c mice infected with Leishmania donovani not only fail to produce IL-1 but also lose the capacity to produce IL-1. This apparent discrepancy is discussed in terms of a possible difference in the induction of cell-mediated immunity between the two leishmanial diseases.
Animals↗
Vaccination against murine cutaneous leishmaniasis by using Leishmania major antigen/liposomes. Optimization and assessment of the requirement for intravenous immunization.
Efficacy of vaccination against cutaneous leishmaniasis in highly susceptible BALB/c mice was assessed comparatively by using radiation-attenuated promastigotes and colloidal Ag mixtures generated from a mixed Leishmania major (LV39) isolate (SLV39) and from a virulent cloned line (SVJ2) derived from the Jericho 2 L. major isolate. Dehydration-rehydration vesicle (DRV) liposomes were used as adjuvants. In optimization experiments phospholipid composition of DRV was varied, and the distearoyl derivative (DSPC) (liquid-crystalline phase transition temperature (Tc) 54 degrees C) of egg lecithin L-alpha-phosphatidylcholine was found to be superior to the dipalmitoyl derivative (DPPC, Tc 41.5 degrees C) and underivatized L-alpha-phosphatidylcholine (Tc -10 degrees C). The criteria studied were in vivo priming for a secondary in vitro proliferative response and the prepatency of lesion onset after L. major challenge of mice immunized once i.v. A single s.c. immunization with SLV39 either free or entrapped within DSPC liposomes primed spleen cells to produce significant levels of IL-3 when stimulated with SLV39 in vitro. In contrast, the i.v. route of immunization with the same Ag preparations led to little or no IL-3 production by the spleen cells. Despite development of significant T cell activation, both SLV39 and SVJ2 administered s.c., either free or entrapped within liposomes, were not protective. However, i.v. immunization four times with SVJ2 entrapped within DSPC liposomes induced a level of resistance comparable with that of 2 x 10(7) gamma-irradiated promastigotes in the stringent BALB/c L. major model. Although significant, protection conferred after i.v. immunization with SLV39/DSPC liposomes was less effective. These data therefore show that DSPC/DRV liposomes, although a good adjuvant for inducing protective immunity to cutaneous leishmaniasis, are not able to overcome the requirement for an i.v. route of immunization with the leishmanial Ag preparation. Additionally, they demonstrate a correlation between IL-3 secretion and non-protection. They also suggest that SVJ2 represents a better source of protective Ag than SLV39.
Adjuvants, Immunologic↗
Macrophage activation by interferon-gamma from host-protective T cells is inhibited by interleukin (IL)3 and IL4 produced by disease-promoting T cells in leishmaniasis.
BALB/c mice are highly susceptible to Leishmania major infection. They develop a progressive fatal disseminating disease even with a minimum infecting dose. However, these mice are able to contain the disease if they are exposed to sublethal gamma-irradiation shortly before infection. Earlier studies demonstrated that CD4+ T cells from mice which had recovered from infection (Tr) can adoptively transfer resistance. In contrast, CD4+ cells from mice with progressive disease (Ts) not only failed to protect, but can reverse the protective effect of the Tr cells. Spleen cells from BALB/c mice which had recovered from L. major infection or which had progressive disease were cultured with leishmanial antigens in vitro. The culture supernatant from spleen cells of recovered mice (TrSN) contains high levels of macrophage-activating factor (MAF) activity which can activate peritoneal macrophages to kill 51Cr-labeled P815 cells and to eliminate intracellular parasites as measured by the reduction in [3H]thymidine uptake by residual parasites released from macrophages following sodium dodecyl sulfate treatment. The MAF activity of TrSN parallels that of recombinant interferon-gamma (IFN-gamma). In contrast, culture supernatant of spleen cells from mice with progressive disease (TsSN) contains no detectable MAF but it is able to neutralize the MAF activity of TrSN. The MAF-inhibiting function of TsSN appears to be mediated by interleukin (IL)3 and IL4, since the MAF activity of TrSN and rIFN-gamma also can be inhibited by the addition of rIL3 and rIL4 but not by rIL1 or rIL2. Furthermore, the MAF-inhibiting activity of TsSN can be partially reversed by the addition of specific anti-IL3 or anti-IL4, but completely reversed by the combination of the two antibodies in vitro. These findings provide a mechanism for the immune regulation in leishmaniasis and a means by which the two subsets of CD4+ T cells influence each other through their modulation of macrophage function.
Animals↗
Distinct IL-3 activation profile induced by intravenous versus subcutaneous routes of immunization.
Lymphoid cells from mice immunized i.v. or s.c. with Leishmania major antigens were analyzed for their capacity to produce lymphokines when stimulated with specific antigens in vitro. Spleen cells from BALB/c mice immunized by the s.c. route produced significantly higher levels of IL-3 and IL-3 mRNA than those from mice immunized by the i.v. route. The differential production of IL-3 was maintained at a wide range of antigen concentrations tested in vitro and for different culturing times. T cell enrichment procedures and treatment with CD4+ mAb in vitro confirmed the T cell nature of the IL-3 producer population. However, the IL-3 production in the two populations of spleen cells was equally high after Con A stimulation in vitro. The IL-2 production by the two populations of cells was also not significantly different after antigen or mitogen stimulation in vitro. To our knowledge, this is the first report of a differential synthesis of IL-3 mRNA and secretion of IL-3 induced by different routes of immunization followed by specific-antigen stimulation in vitro. These findings may also explain earlier observations that i.v. immunization with leishmanial antigen induces protection, whereas s.c. immunization leads to exacerbation of L. major infection, since IL-3 has been previously shown to promote leishmanial infection. The fact that the phenomenon also extends to other antigen systems suggests that this finding may have a broader implication in immune regulation and vaccine development.
Animals↗
Functional heterogeneity of CD4+ T cells in leishmaniasis.
In this article F.Y. Liew summarizes the evidence for the functional heterogeneity of CD4+ T cells from studies of immune regulation in the parasitic disease, leishmaniasis. Recent findings suggest that the heterogeneity of CD4+ T cells may extend beyond the current Th1 and Th2 classification and that these T-cell subsets manifest some of their functions via the lymphokines they secrete, and that the balance of these determines the outcome of the infection.
Animals↗
Effect of CD4 monoclonal antibody in vivo on lesion development, delayed-type hypersensitivity and interleukin 3 production in experimental murine cutaneous leishmaniasis.
Highly susceptible BALB/c mice subjected to adult thymectomy followed by prolonged (15 weeks), twice-weekly injections of a low dose (100 micrograms) of CD4 monoclonal antibody (MoAb) develop resistance to otherwise uniformly fatal and disseminating Leishmania major infection. In contrast, similar treatment with CD8 MoAb has no effect on the course of L. major infection. CD4 MoAb administered after the lesion establishment also has no effect. Mice which become resistant following CD4 MoAb treatment developed the classical delayed-type hypersensitivity (DTH) which persisted at 72 h after footpad injection with killed L. major promastigotes. A substantial degree of resistance can also be induced in the BALB/c mice with two i.v. high doses of 500 micrograms of CD4 MoAb given immediately prior to L. major infection. The treated mice developed classical DTH and significantly smaller lesions. The spleen cells from these mice also produced significantly lower levels of IL-3 compared to that of untreated control mice when cultured with L. major antigens in vitro. In contrast, genetically resistant CBA mice treated with CD4 MoAb developed significantly larger lesions but lower levels of classical DTH compared to untreated mice. These data confirmed and extended earlier reports on the prophylactic effect of CD4 MoAb in susceptible BALB/c mice and the disease exacerbative effect in the resistant CBA mice. The data also further illustrate the direct correlation between classical DTH and resistance, and the inverse correlation between IL-3 production and resistance in experimental cutaneous leishmaniasis.
Animals↗
Antiviral immunity induced by recombinant nucleoprotein of influenza A virus. I. Characteristics and cross-reactivity of T cell responses.
The gene for the nucleoprotein of the A/NT/60/68 influenza virus was expressed in bacteria and the recombinant protein purified. Lymph node cells from mice immunized with recombinant nucleoprotein proliferated in response to in vitro stimulation with a range of type A influenza viruses. Proliferation was inhibited by mAb to CD4 and class II MHC gene products. IFN-gamma was produced and type-specific CTL were generated in stimulated cultures of immune lymph node cells. These CTL were CD4+ and restricted to class II MHC gene products. Immunization with recombinant nucleoprotein generated Th cells in vivo as measured by the ability to generate an accelerated response to hemagglutinin after challenge with inactivated virus. The results are discussed with reference to a cross-reactive vaccine against influenza.
Animals↗
Suppressive substance produced by T cells from mice chronically infected with Trypanosoma cruzi. III. Genetic restriction and further characterization.
Earlier papers in this series reported that the culture supernatant of splenic L3T4+, Lyt-2- T cells from susceptible CBA mice chronically infected with Trypanosoma cruzi contain a SS3 that can inhibit the induction of delayed-type hypersensitivity to a wide range of Ag. The SS is a glycoprotein with an apparent molecular mass of 30 to 60 kDa and is distinct from T. cruzi Ag, IL-1, IL-2, IL-3 or IFN-gamma. It also has no effect on Th cells for antibody, cytotoxic T cells or immediate-type hypersensitivity. In this paper, we report that SS can suppress the induction of proliferating T cells but not the presentation of Ag to a cloned T cell line (D10). It also has no effect on the induction of delayed-type hypersensitivity in vitro. SS is produced by a number of inbred mouse strains irrespective of their susceptibility to infection with T. cruzi (BALB/c, highly susceptible; CBA, susceptible; C57BL/10, resistant) but only CBA mice are sensitive to the suppressive action of SS. This is so whether the SS is derived from CBA, BALB/c, or C57BL/10. The sensitivity to SS is not a feature of the H-2k haplotype inasmuch as B10.BR and BALB/k mice (also H-2k) do not respond to SS. Attempts to purify SS with a range of biochemical techniques substantially enriched the specific activity but failed to produce a substance visualizable by analytical gel electrophoresis. IEF chromatography revealed SS activity spanning a pH range from 6 to less than 4. This suggests that SS is likely to be a minor heterogeneous component of the suppressive supernatant. The genetically highly restricted nature of its action is intriguing and may explain some of the contradictory reports in the literature on this subject.
Animals↗
Suppression of IL-2 production by cryopreserved peripheral blood mononuclear cells from patients with active visceral leishmaniasis in Sicily.
The ability of PBMC from eight patients with confirmed visceral leishmaniasis (Leishmania donovani) to produce IL-2 in response to PHA in vitro was investigated. PBMC from the patients produced significantly lower levels of IL-2 and had reduced proliferative response to PHA at the time of disease diagnosis compared with healthy controls. Their ability to produce IL-1 in response to LPS was, however, unaltered. The patients also showed normal levels of OKT4+ and IL-2R+ cells in the peripheral blood, as judged by specific immunofluorescence staining. All patients were given antimony therapy, and five were cured. The recovered patients showed significant improvement in the IL-2 producing capacity of their PBMC. The PBMC preparations of patients and controls were cryopreserved before and after successful chemotherapy on the patients. The frozen cell preparations were thawed and viable autologous cells cocultured with equal numbers of PBMC from patients before and after chemotherapy. The frozen cells from five healthy controls showed little or no difference whether they were cultured together or separately. In contrast, coculturing of cells from the five recovered patients with autologous pretreatment cells produced significantly and consistently lower levels of IL-2 compared with those produced when the cells were cultured separately. These results therefore demonstrate that the PBMC from patients with visceral leishmaniasis contain a population of cells that are capable of suppressing the IL-2 production by autologous PBMC from recovered patients. The method of cryopreservation should be useful for studying the immune regulation in this and other clinical diseases in vitro.
Adult↗