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The safety and immunogenicity of an intramuscular (i.m.) and intradermal (ID) formulation of autoclaved Leishmania (Leishmania) amazonensis vaccine was evaluated in 296 volunteers in a randomized, placebo-controlled, double-blind trial in Colombia. There were 4 vaccination groups: i.m. vaccine, i.m. placebo, ID vaccine, and ID placebo. The ID formulations were mixed with BCG as adjuvant at the time of injection. For each group, 3 vaccinations were given with a 20-day interval between injections, and adverse events were monitored at 20 min, and at 2, 7 and 21 days after each injection. BCG-induced adverse reactions resulted in cancellation of the third vaccine administration in the ID groups. Antibody titres did not differ significantly between the groups. Montenegro skin-test conversion was achieved by 86.4% and 90% of the i.m. vaccine group and by 25% and 5% of the i.m. placebo group 80 days and 1 year after vaccination, respectively. A significant increase in mean Leishmania-antigen lymphocyte proliferation indexes was observed after i.m. vaccine immunization, but not after i.m. placebo immunization, 80 days and 1 year after vaccination. Significant levels of IFN gamma but not IL-10 were observed 1 year after vaccination in the i.m. vaccine group compared to the i.m. placebo group. The good safety profile and evidence of Th1 immune reactions due to i.m. vaccination in this phase-I/II study suggest that a population-based phase-III efficacy trial of the i.m. vaccine should be initiated.
By virtue of their strong bias towards production of interferon-gamma (IFN-gamma), CD8+ T cells have the potential to promote the development of type 1 immune responses. We have previously shown that the CD4+ T-cell response to immunization with the protein antigen keyhole limpet haemocyanin (KLH) has a mixed interleukin-4 (IL-4)/IFN-gamma production profile. Here we show that this immunization regimen also stimulates accumulation in the draining lymph nodes of CD8+ T cells, which preferentially contain IFN-gamma mRNA ex vivo and secrete IFN-gamma protein in vitro. This provides a model to test whether CD8+ cell-derived IFN-gamma participates in the normal control of the immune response to a non-viable exogenous antigen. To investigate regulation of the anti-KLH response by the CD8+ population or IFN-gamma produced by this or other cell types, mice were administered depleting antibodies. Depletion of CD8+ cells had no effect on the frequency of clonogenic KLH-specific CD4+ T cells, the IL-4/IFN-gamma profiles of their progeny, or the isotype profiles of the serum antibody response to KLH. In contrast, IFN-gamma neutralization diminished cell accumulation in the lymph nodes and reduced both the frequency of KLH-specific CD4+ T cells that gave rise to IFN-gamma-producing clones and serum titres of KLH-specific IgG2a and IgG3. Therefore, despite the potential for cross-regulation, the CD4+ T-cell response to this immunogen is independent of the IFN-gamma-skewed CD8+ response.
BACKGROUND: The relative contribution of HLA class I molecules-including classical HLA class Ia (HLA-A, -B, -C) and non-classical HLA class Ib (HLA-E, -F, -G)-to shaping the tumor immune microenvironment in colon cancer remains insufficiently defined. We investigated how their expression patterns relate to immune infiltration and clinical outcome. METHODS: In a retrospective cohort of 280 colon cancers, we assessed HLA class Ia and class Ib expression and quantified CD45-positive immune cell infiltration by immunohistochemistry. These features were correlated with clinicopathological variables, microsatellite instability (MSI) status, and previously established genomic immune signatures. RESULTS: High HLA class Ia expression and increased CD45-positive cell infiltration were each associated with improved overall, disease-specific, and progression-free survival. CD45-positive density correlated strongly with Immunologic Constant of Rejection scores. HLA class Ia loss was more frequent in advanced stages and in MSI-H tumors. Among HLA class Ib molecules, only HLA-E expression was associated with favorable disease-specific and progression-free survival. Integrative analysis identified three immune phenotypes with distinct prognostic profiles; tumors characterized by high HLA class Ia expression, low HLA class Ib expression, and high CD45-positive infiltration had the best outcomes. CONCLUSION: Colon cancer immunogenicity is shaped by coordinated patterns of HLA class I expression and immune infiltration. Integrating HLA class Ia/Ib expression with immune cell density provides a refined stratification of tumor immune phenotypes and may support personalized immunotherapeutic decision-making.
Cancer immunotherapy has reshaped oncology, largely through immune checkpoint inhibitors that release the brakes on tumor-reactive T cells. Yet the benefit remains uneven, and that unevenness traces back to a few basic biological limits. Checkpoint blockade amplifies immunity that is already present; it does not create tumor specificity de novo. Poor Ag quality, defective Ag presentation, a suppressive microenvironment, and epigenetically fixed T-cell exhaustion together set a ceiling on what checkpoint release can achieve. Next-generation strategies try to move past these limits by reorganizing immunotherapy around the functional layers of the immune response. Cancer vaccines define tumor-specific neoantigens and expand the responses against them. Ab-based approaches tune inhibitory signaling, draw immune cells toward the tumor, and trigger immunogenic cell death. Cellular therapies-chimeric Ag receptor T cell, TCR-engineered T cells, and tumor-infiltrating lymphocytes (TILs)-boost effector potency, with TIL therapy notable for preserving tumor-reactive repertoires shaped in vivo. Rather than rivals, these modalities are best seen as complementary layers-Ag definition, immune priming, effector optimization, and microenvironmental conditioning-to be combined in a programmable way. As genomic profiling, immunopeptidomics, and high-dimensional immune monitoring mature, the field is shifting from checkpoint-centered release toward precision immunoengineering, in which tumor-specific immunity is deliberately designed, aligned, and sustained.
The need for a vaccine against Leishmania spp., a major cause of worldwide morbidity and mortality, is urgent. We tested the efficacy of an experimental vaccination in murine models of cutaneous leishmaniasis, using dendritic cells (DCs) pulsed with synthetic or native parasite antigens. DCs pulsed with peptide 154-169aa of gp63 or soluble promastigote lysate (SPL) triggered antigen-specific immune responses and efficiently reduced lesion formation and parasite load of genetically susceptible BALB/c mice infected with Leishmania major. This effect was accompanied by a modulation of the cellular immune response towards a Th1 profile. Vaccination of genetically resistant CBA mice with DCs pulsed with peptide 154-169aa or SPL did not affect the course of the disease, whereas pulsing with the epitope 467-482aa of gp63 resulted in disease exacerbation, accompanied by a switch to a Th2 profile. In view of our continuously growing knowledge about the immunobiology of DCs, these findings suggest that vaccination with DCs pulsed with defined peptides could be a strategy against infectious diseases. Peptide selection is a prerequisite as they can differentially regulate the type of immune response in susceptible or resistant hosts.
Amino acid residues 421-436 constitute a comparatively conserved determinant of gp120 that participates in the binding of host cell CD4 receptors by HIV-1. We compared the immunogenicity of synthetic Cys-gp120 (421-436) conjugated to KLH via the N terminal Cys residue (KLH-I) and gp120 (421-436) extended at its N terminus with a 15 residue tetanus toxoid T cell epitope (T-I) in non-autoimmune mice (BALB/cstrain) and Fas-defective autoimmune mice (MRL/lpr strain). Both immunogens elicited high titer Abs detected as the binding to gp120 (421-436) conjugated to bovine serum albumin (BSA-I) immobilized in ELISA plates. Abs from KLH-I immunized mice displayed binding to full-length gp120 but the Abs from T-I immunized mice did not. Proteins unrelated in sequence to gp120 did not bind the Abs. Soluble I and T-I failed to compete with immobilized BSA-I for binding to anti-KLH-I Abs, whereas these peptides inhibited anti-T-I Ab binding by BSA-I (rank potency order: BSA-I > T-I >> I). These results indicate the influence of the carrier protein on the specificity of Abs to synthetic I. Low level BSA-I and gp120 binding Abs were detected in sera from non-immunized MRL/lpr mice. Similar Ab binding titers and specificity profiles were evident in MRL/lpr and BALB/c mice following immunization with KLH-I and T-I, indicating that pre-existing immunity to gp120 in the former strain does not influence the magnitude or specificity of the Ab response.
Listeria monocytogenes (L. monocytogenes) is a promising candidate vaccine vector that naturally infects antigen-presenting cells, and targets antigen delivery to both the class I MHC pathway of endogenous antigen presentation and the class II pathway of exogenous antigen presentation. At the same time, L. monocytogenes stimulates the innate immune response to produce cytokines that enhance antigen-presenting function and induce a Th1-type cytokine profile associated with cell-mediated immune responses. Immune responses with these features are considered to be particularly important for clearance of viruses, tumors, and intracellular infections. In this review, we describe the development of methods to transform L. monocytogenes to express and secrete foreign antigens and the studies that have demonstrated that genetically engineered L. monocytogenes mutants are highly effective vectors for the induction of potent immune responses against viral antigens and tumor cells. In addition, we discuss the strengths and weaknesses of L. monocytogenes as a vaccine vector.
Hypersensitivity reactions to drugs and environmental agents are often due to exaggerated humoral (Th(2)) or cell mediated (Th(1)) immune responses with typical cytokine profiles. Overexpression of Th(2) cytokines, such as IL-4, IL-5 or IL-13 in mice, enhances an IgE antibody mediated response, while deletion of these cytokines attenuates and/or prevents allergic responses. Conversely, modulation of Th(1) cytokine gene expression may affect cell-mediated immune responses. Therefore, cytokine transgenic mice are used as investigative tools to study potential chemicals and/or drug allergies. In addition to cytokines and chemokines, other factors are important for the development of allergic responses, such as IgE, Fc receptors, vasopressin and several other factors, which can be tested in transgenic mice.
We wish to report the results of a retrospective study of patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC) as well as a group of asymptomatic human immunodeficiency virus (HIV)-infected individuals, in whom we examined markers of systemic autoimmune disease including anti-cell antibodies, immunoglobulin (Ig) and complement (C3 and C4) profiles as well as circulating immune complexes (CIC). Antibodies to cytoplasmic (but not nuclear) antigens were significantly elevated in the AIDS and ARC groups when compared with a population of normal individuals (for AIDS, P = 0.0002 vs. control; for ARC, P = 0.0004 vs. control). The non-AIDS/ARC, HIV+ group did not demonstrate significance (P = 0.054). Each of the three study groups also demonstrated increased Ig (P less than 0.05 for each immunoglobulin class). CIC, as determined by a Clq-binding enzyme immunoassay, were higher in all three study groups (P less than 0.05) when compared with controls. C3 and C4 were not significantly lower than control subjects (P greater than 0.05), but C4 did demonstrate a significant (P = 0.01) inverse correlation with CIC. These findings strengthen the hypothesized autoimmune aspect of AIDS and ARC, and extend this concept to include HIV-infected individuals without frank disease.
Inbred mouse strains differ in susceptibility to Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease. A strong correlation between disease susceptibility and delayed-type hypersensitivity (DTH) has been previously demonstrated, but no strong correlation between disease susceptibility and total anti-TMEV ELISA titres was shown. Since both DTH and IgG2a antibody production are regulated by CD4+ Th1 cells, we investigated three strains of mice to determine whether antivirus IgG2a antibody levels, like DTH in previous studies, correlated with disease susceptibility. Susceptible SJL/J, intermediately susceptible C3H/HeJ, and resistant C57BL/6 mice were infected intracerebrally (i.c.) with the BeAn strain of TMEV and monitored for clinical signs of demyelination and for levels of TMEV-specific antibody of different IgG subclasses using a particle concentration fluorescence immunoassay (PCFIA). Resistant C57BL/6 mice were found to have significantly lower concentrations of total anti-TMEV antibody than susceptible SJL/J mice and intermediately susceptible C3H/HeJ mice show variable antibody responses. A predominance of anti-TMEV IgG2a (Th1 regulated) antibody was seen in susceptible and intermediately susceptible mice, whereas resistant mice displayed a predominant anti-TMEV IgG1 (Th2 regulated) response accompanied by a marked deficiency of IgG2a. In contrast, immunization of C57BL/6 mice with UV-inactivated TMEV in adjuvant revealed that this strain was not defective either in its ability to generate high levels of anti-TMEV antibody or in its ability to produce IgG2a antibody. These results suggest that the antivirus IgG subclass profile is dependent upon the immunization route, virus viability and/or the use of adjuvant and that the levels of antivirus subclasses may be predictive of disease susceptibility.
The study of differentiation antigens of circulating mononuclear cells in 70 patients with primary immunodeficiency (PID) using monoclonal antibodies allowed us to define phenotypic profiles that are characteristic of the different described syndromes. In common variable immunodeficiency we found percentages of lymphocytes within normal ranges, and an altered CD4/CD8 ratio. In sex-linked agammaglobulinemia, absence of B lymphocytes with normal distribution of regulatory populations (CD4/CD8) were found. These results allow us to distinguish two clinically and infectologically similar conditions. In selective IgA deficiency, distribution of lymphocytic populations was normal. In immunodeficiency with hyper IgM, considered up to date as an abnormal maturation of B lymphocytes, we observed a deficiency in cellular immune response, and a phenotypic profile characterized by: decreased number of CD3 cells, inverted CD4/CD8 ratio, and increased CD38 population; this profile being similar to the one that we found in predominantly cellular immunodeficiency. In predominantly cell-mediated immunodeficiency and in those immunodeficiencies associated to other defects (such as: hyper IgE syndrome, Di George syndrome), the most important finding was a significative increase in CD38 population. Although it's not possible to consider on this basis that there is a defect at the thymic level of T-cells maturation, the high levels of circulating CD38 cells were a clear indication of altered cellular immune response in our series of patients. Patients with predominantly cell-mediated immunodeficiency showed the lowest levels of CD4 cells and the corresponding inversion of CD4/CD8 ratio. In Di George syndrome we found a markedly diminished CD8 population that differentiates this entity from the rest of the studied syndromes. In chronic mucocutaneous candidosis distribution of lymphocytic populations was normal, but a significative increase in the percentages of CD11b+ cells was observed. In patients with antibodies deficiency that received substitutive treatment with gammaglobulin we found no variations in lymphocytic populations distribution. In the group of patients with altered cellular immunity treated with thymic hormones, observed phenotypic changes (increase in T-cells population, trend to normalization in CD4/CD8 ratio, and decrease in CD38 population) were transient, and lasted only during the treatment period. We considered that describing these phenotypic profiles is a useful diagnosis tool when evaluating patients with PID, since these profiles are characteristic and very stable.
In order to investigate the T cell cytokine profile during age-dependent maturation of the immune response, we evaluated the cytokine expression of CD4+ and CD8+ circulating cells by flow cytometric single-cell analysis after non-specific stimulation in vitro in different age groups of normal individuals, from cord blood to adulthood. Moreover, we correlated these lymphocyte cytokine patterns with the expression/release of CD30, a member of the tumour necrosis factor (TNF) receptor superfamily, which has been suggested to be related to the T helper/cytotoxic (Th(c))2-type immune responses, in order to verify this association in vivo, in non-pathological conditions. The results showed a progressive increase of circulating Th(c)1-type, interferon-gamma (IFN-gamma)- and/or IL-2-producing T cells along with ageing and, conversely, a stable number, although higher than in cord blood samples, of CD4+/IL-4+ T cells in the post-natal groups. In addition, serum levels of soluble CD30 (sCD30) and numbers of circulating CD4+/CD30+ and CD8+/CD30+ T cells were significantly higher in children aged < 5 years in comparison with those found either in cord blood or in blood from both older children and adults. These data support the concept of a progressive polarization of the Th(c) cell cytokine profile towards the Th(c)1 pattern during age-dependent maturation of the immune response. Moreover, the peak of CD30 expression/release in early infancy before the Th(c)1 shifting occurs, although not associated with a significant increase of circulating IL-4+ T cells, raises the question of the possible relationship in vivo between CD30 and Th(c)2-type immune responses.
SB 203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4- pyridyl)imidazole], a selective cytokine suppressive binding protein/p38 kinase inhibitor, was evaluated in several models of cytokine inhibition and inflammatory disease. It was demonstrated clearly to be a potent inhibitor of inflammatory cytokine production in vivo in both mice and rats with IC50 values of 15 to 25 mg/kg. SB 203580 possessed therapeutic activity in collagen-induced arthritis in DBA/LACJ mice with a dose of 50 mg/kg resulting in significant inhibition of paw inflammation and serum amyloid protein levels. Antiarthritic activity was also observed in adjuvant-induced arthritis in the Lewis rat when SB 203580 was administered p.o. at 30 and 60 mg/kg. Evidence for disease-modifying activity in this model was indicated by an improvement in bone mineral density and by histological evaluation. Additional evidence for beneficial effects on bone resorption was provided in the fetal rat long bone assay in which SB 203580 inhibited 45Ca release with an IC50 of 0.6 microM. In keeping with the inhibitory effects on lipopolysaccharide-induced tumor necrosis factor-alpha in mice, SB 203580 was found to reduce mortality in a murine model of endotoxin-induced shock. In immune function studies in mice treated with SB 203580 (60 mg/kg/day for 2 weeks), there was some suppression of an antibody response to ovalbumin, whereas cellular immune functions measured ex vivo were unaffected. This novel profile of activity strongly suggests that cytokine inhibitors could provide significant benefit in the therapy of chronic inflammatory disease.
Adenylate cyclase toxin (CyaA) from Bordetella pertussis can subvert host immune responses allowing bacterial colonization. Here we have examined its adjuvant and immunomodulatory properties and the possible contribution of lipopolysaccharide (LPS), known to be present in purified CyaA preparations. CyaA enhanced antigen-specific interleukin-5 (IL-5) and IL-10 production and immunoglobulin G1 antibodies to coadministered antigen in vivo. Antigen-specific CD4(+)-T-cell clones generated from mice immunized with antigen and CyaA had cytokine profiles characteristic of Th2 or type 1 regulatory T (Tr1) cells. Since innate immune cells direct the induction of T-cell subtypes, we examined the influence of CyaA on activation of dendritic cells (DC) and macrophages. CyaA significantly augmented LPS-induced IL-6 and IL-10 and inhibited LPS-driven tumor necrosis factor alpha and IL-12p70 production from bone marrow-derived DC and macrophages. CyaA also enhanced cell surface expression of CD80, CD86, and major histocompatibility class II on immature DC. The stimulatory activity of our CyaA preparation for IL-10 production and CD80, CD86, and major histocompatibility complex class II expression was attenuated following the addition of polymyxin B or with the use of DC from Toll-like receptor (TLR) 4-defective mice. However, treatment of DC with LPS alone at the concentration present in the CyaA preparation (0.2 ng/ml) failed to activate DC in vitro. Our findings demonstrate that activation of innate cells in vitro by CyaA is dependent on a second signal through a TLR and that CyaA can promote Th2/Tr1-cell responses by inhibiting IL-12 and promoting IL-10 production by DC and macrophages.
A feature of pulpal immune responses is the predominance of type 1 cytokine mRNA under shallow caries and a mixed (type 1/type 2) profile under deep caries. These results prompted an examination of the cytokine profiles induced by bacteria in shallow caries (Streptococcus mutans and Actinomyces viscosus) and deep caries (Lactobacillus casei, Pseudoramibacter alactolyticus, and Prevotella intermedia). All isolates induced interferon-gamma and interleukin-10, whereas interleukin-4 and interleukin-2 titers were low to undetectable. S. mutans was the most potent and persistent interferon-gamma inducer. Differences in interleukin-10 were apparent at low doses but were less dramatic, with L. casei the dominant producer. S. mutans induced substantially more interferon-gamma than interleukin-10 over all doses and time points, suggesting strong type 1 polarization. P. alactolyticus induced significantly more interleukin-10 than interferon-gamma at higher concentrations, suggesting polarization toward type 2. A similar amount of interferon-gamma and interleukin-10 induced by L. casei, A. viscosus, and P. intermedia reflected a mixed profile. A better understanding of pulpal immune response to caries bacteria may enable us to develop an immune system-based pulp therapy in the future.
At this stage in the COVID-19 pandemic, most infections are "breakthrough" infections that occur in individuals with prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure. To refine long-term vaccine strategies against emerging variants, we examined both innate and adaptive immunity in breakthrough infections. We performed single-cell transcriptomic, proteomic, and functional profiling of primary and breakthrough infections to compare immune responses from unvaccinated and vaccinated individuals during the SARS-CoV-2 Delta wave. Breakthrough infections were characterized by a less activated transcriptomic profile in monocytes and natural killer cells, with induction of pathways limiting monocyte migratory potential and natural killer cell proliferation. Furthermore, we observed a female-specific increase in transcriptomic and proteomic activation of multiple innate immune cell subsets during breakthrough infections. These insights suggest that prior SARS-CoV-2 vaccination prevents overactivation of innate immune responses during breakthrough infections with discernible sex-specific patterns and underscore the potential of harnessing vaccines in mitigating pathologic immune responses resulting from overactivation.
We have examined the ability of mice to survive a lethal challenge with the parasitic hemoflagellate, Trypanosoma cruzi, following immunization with paraflagellar rod proteins (PAR) 1 and 2 either alone or in combination with the following adjuvants: Freund's, alum, QS-21, Ribi-700, or IL-12. PAR administered subcutaneously (sc) in combination with Freund's or alum provided significant protection, 100 and 83%, respectively, against a T. cruzi challenge. In contrast, PAR in combination with QS-21, Ribi-700, IL-12, or Freund's administered intraperitoneally (ip) or PAR alone provide no protection against a challenge. PAR-specific serum antibody titers and isotype profiles for several of the immunization regimens were determined, and no positive correlation could be seen between a protective immune response and either antibody titer or the subclass of antibody induced. We also examined the ability of PAR to stimulate T cells from the spleen and lymph nodes of mice immunized with PAR in combination with Freund's (sc), Freund's (ip), alum, or Ribi-700. Each of the adjuvants strongly enhanced the ability of enriched T cells to proliferate in a PAR-specific fashion, suggesting no obvious correlation between PAR-specific T cell activation and protection. However, examination of the cytokine profiles of the stimulated T cell groups showed that the protective groups differed from the nonprotective groups. While all four groups showed low levels of IL-10, the Freund's (sc) and alum groups had higher levels of IFN-gamma and IL-2 than Freund's (ip) and Ribi-700 groups, and most strikingly, no IL-4 could be detected in either the Freund's (sc) or the alum group, in contrast to significant levels of IL-4 in both the Freund's (ip) and the Ribi-700 group. These findings indicate that protective immunity in mice immunized with PAR is associated with a Th1-type response.