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PubMed1983

Studies of the mechanisms for the induction of in vivo tumor immunity. VII. Development of specific antitumor immunity in progressors and regressors.

The present study was aimed at comparing the development of specific antitumor immunity between hosts with progressively growing tumors and hosts with regressing tumors. The experiments were performed with a Friend virus-induced leukemia FBL-3 in syngeneic C57BL/6 mice. The specific antitumor immunity was determined by in vitro cell-mediated cytotoxicity assay and in vivo tumor neutralization test. Both the systemic immunity (demonstrated in spleen) and immunity developed at tumor site were examined. For progressors, the tumor site was in the peritoneal cavity. For regressors, it was in a subcutaneous site of both flanks. Testing by the cell-mediated cytotoxicity assay showed that immune hosts and regressors had higher levels of systemic immunity than the progressors. However, when lymphocytes isolated from tumor sites were assayed, it was found that there was no remarkable difference between lymphocytes from progressor tumors (PTL) and lymphocytes from regressor tumors (RTL). Both lymphocyte populations were similar in profile analysis; they were characterized as T cells and possessed the same antigenic specificity. Nevertheless, when in vivo tumor transplantation experiments were performed, RTL were found to give protection against FBL-3 challenge whereas PTL consistently failed to do so. On cytomorphological examination, the PTL were seen to contain large amounts of macrophages. The presence of macrophages in PTL appeared to have an inverse relationship to the in vivo protective effect. After removal of macrophages from PTL by Petri dish adherence, the nonadherent PTL were found to give in vivo protection. Furthermore, thymocytes from progressors and macrophages isolated from the progressor tumors were found to suppress the in vivo T-cell-mediated immunity. These findings demonstrated that suppressor T cells and suppressor macrophages were present in tumor-bearing hosts. These suppressor cells could interfere with the function of immune T cells at the efferent arm of the immune response.

Animals↗

PubMed1987

The common mucosal immune system and current strategies for induction of immune responses in external secretions.

The selective induction of antibodies in external secretions is desirable for the prevention of various systemic as well as predominantly mucosa-restricted infections. An enormous surface area of mucosal membranes is protected primarily by antibodies that belong, in many species, to the IgA isotype. Such antibodies are produced locally by large numbers of IgA-containing plasma cells distributed in subepithelial spaces of mucosal membranes and in the stroma of secretory glands. In humans and in some animal species, plasma-derived IgA antibodies do not enter external secretions in significant quantities and systemically administered preformed IgA antibodies would be of little use for passive immunization. Systemic administration of microbial antigens may boost an effective S-IgA immune response only in a situation whereby an immunized individual had previously encountered the same antigen by the mucosal route. Local injection of antigen in the vicinity of secretory glands is usually accompanied by an undesirable concomitant systemic response and frequently requires the addition of adjuvants that are unacceptable for administration in humans. Immunization routes that involve ingestion or possibly inhalation of antigens lead to the induction of not only local but also generalized immune responses manifested by the parallel appearance of S-Iga antibodies to ingested or inhaled antigens in secretions of glands distant from the site of immunization. Based on extensive studies in animal models as well as in humans, convincing evidence is available that antigen-sensitized and IgA-committed precursors of plasma cells from GALT are disseminated to the gut, other mucosa-associated tissues, and exocrine glands. However, due to the limited absorption of desired antigens from the gut lumen of orally immunized individuals, repeated large doses of antigens are required for an effective S-IgA response. Novel antigen delivery systems for the stimulation of such responses are currently being examined in several laboratories. Live attenuated or genetically manipulated bacteria expressing other microbial antigens have also been used for selective colonization of gut-associated lymphoid tissues. Unique antigen packaging and the use of adjuvants suitable for oral administration hold promise for an efficient antigen delivery to critical tissues in the intestine and deserve extensive exploration. The oral immunization route appears to have many advantages over systemic immunization.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1988

Trypanosoma cruzi: immune response in mice immunized with parasite antigens.

The humoral and cellular immune responses were studied in mice immunized with flagellar fraction (F), F plus Bordetella pertussis as adjuvant (F-Bp), and microsomal (Mc) subcellular fractions from the epimastigote forms of Trypanosoma cruzi. The immune response was studied before and after the challenge with 50 bloodstream forms of T. cruzi, Tulahuén strain. The immunization with F-Bp, but not with Mc or F and Bp separately, protected mice, in terms of parasitemia and mortality, from the challenge with the parasite. Before the challenge, levels of specific antibodies in mice immunized with F-Bp were higher than in mice immunized with F or Mc. Antibody levels 17 days after the infection were similar in the three groups of mice while nonimmunized mice reached lower levels. Early during the infection nonimmunized infected mice lacked delayed-type hypersensitivity (DTH) responses to parasite antigens and to concanavalin A (Con A). Mice immunized with F-Bp, however, presented positive DTH responses to parasite antigens and Con A both, before and after the challenge with T. cruzi. DTH reaction was transferred with spleen cells. Mice immunized with Mc behaved similarly to infected nonimmunized animals in their reactivity to parasite antigens. These results indicated striking differences between protected and nonprotected mice in humoral and cellular immune responses during experimental T. cruzi infection.

Adjuvants, Immunologic↗

PubMed1995

Immune responses and protection against Bordetella pertussis infection after intranasal immunization of mice with filamentous haemagglutinin in solution or incorporated in biodegradable microparticles.

The intranasal (i.n.) immunization of mice with Bordetella pertussis filamentous haemagglutinin (FHA) either as a solution or incorporated in biodegradable microparticles induced very similar immune responses. Both resulted in strong systemic IgG responses to FHA and good levels of anti-FHA IgG and IgA in the lungs of immunized mice. In comparison, the intraperitoneal (i.p.) immunization of mice with FHA, as a solution, engendered anti-FHA antibody responses which were stronger for serum IgG, similar for lung IgG and lower for lung IgA. The anti-FHA antibody levels, as measured by immunosorbent assay, were shown to correlate with their functional activity in the blocking of B. pertussis adhesion to HeLa tissue-culture cells. All three forms of immunization appeared to stimulate T-cell responses as assessed by in vitro antigen-specific spleen cell proliferation and IL-2 secretion indicative of a Th1 type response, however, cells from i.p. immunized mice only secreted low levels of IL-5. All three methods of FHA immunization provided mice with significant protection against subsequent aerosol challenge with virulent B. pertussis. Mice which had been immunized intra-nasally eliminated the bacteria from their lungs slightly more rapidly than i.p. immunized mice, demonstrating the efficacy of intranasal administration of FHA in solution and in the more practical biodegradable microparticle form.

Administration, Intranasal↗

PubMed2004

Alternative diphtheria, tetanus and whooping cough immunization schedule to evoke a Th2 tetanus and a Th1 pertussis immune response.

In a previous study, using BALB/c mice, we found that while diphtheria (D), tetanus (T) and whooping cough (Pw, whole-cell Bordetella pertussis) immunization induces a Th1/Th2 tetanus response and memory T cells able to proliferate in response to in vitro stimulation with B. pertussis, DTPa immunization induces a Th2 tetanus immune response and no memory T cells that recognize B. pertussis as stimulus. Considering that a pro-inflammatory cytokine production is not necessary for protection against tetanus and therefore should be avoided, an alternative DTP immunization schedule with minimal Pw exposure was assessed in order to obtain a Th2 tetanus response and a Th1 pertussis response. BALB/c mice were primed with DT vaccine at day 0, with Pw vaccine at day 14 and boosted with DTPa vaccine at days 21 and 28. A control group was inoculated with saline. Antibodies against B. pertussis surface antigens, tetanus and diphtheria toxoids were produced by mice. Spleen cells stimulated in vitro with B. pertussis produced IL-6 and IFNgamma. Only IL-5 was produced by cells in response to tetanus toxoid stimulation. These results are in line with the low IgG1/IgG2a ratio for pertussis antibodies compared with those corresponding to tetanus and diphtheria. The immunization protocol presented herein succeeded in producing tetanus and pertussis immune responses of Th2 and Th1 type, respectively. In contrast to previous results obtained with DTPw immunization, no IL-12 production was observed. Our findings provide direct evidence that an immunization protocol with an interval of 14 days between DT and Pw primings, followed by DTPa boosters, can induce appropriate immune responses against DTP vaccine antigens.

Animals↗

PubMed2005

Immune suppression in cancer: effects on immune cells, mechanisms and future therapeutic intervention.

Evidence indicates that the healthy immune system is necessary for control of malignant disease and that immune suppression associated with cancer contributes to its progression. Tumors have developed strategies to successfully evade the host immune system, and various molecular and cellular mechanisms responsible for tumor evasion have been identified. Certain of these mechanisms target immune anti-tumor effector cells. Dysfunction and apoptosis of these cells in the tumor-bearing host creates an immune imbalance that cannot be corrected by immunotherapies aimed only at activation of anti-tumor immune responses. Reversal of existing immune dysfunction(s) and normalization of lymphocyte homeostasis in patients with cancer needs to be a part of future cancer immunotherapy. Therapeutic strategies are being designed to correct the immune imbalance, deliver adequate in vivo stimulation, transfer effector T cells capable of in vivo expansion and provide protection for the immune effector cells re-populating the host. Survival of these cells and long-term memory development in patients with malignancy are necessary for improving clinical benefits of cancer immunotherapies.

Humans↗

PubMed2005

Induction of active immune suppression by co-immunization with DNA- and protein-based vaccines.

Although immunization has been used for eliciting immune response, here we show that it can also induce immune suppression. When a DNA vaccine encoding a viral antigen such as the VP1 protein from the foot and mouth disease virus is administered together with its recombinant protein antigen or a viral preparation containing the same antigen, the immunized animals developed significantly reduced antigen-specific T cell-mediated responses and became impaired to subsequent rechallenge with the same antigen. The induction of immune suppression is mediated by suppressor T cells, as demonstrated by an adoptive transfer experiment and mixed lymphocyte reactions. The induction of immune suppression in immunized animals is also correlated with a shift of cytokine balance, as reflected by an elevated level of IL-10 and reduced level of IFN-gamma or IL-2. Hence, co-immunization with DNA- and protein-based vaccines may represent a novel means for inducing active suppression against untoward immunity.

Animals↗

PubMed2004

Immunization with cytoplasmic repetitive antigen and flagellar repetitive antigen of Trypanosoma cruzi stimulates a cellular immune response in mice.

In previous studies, we demonstrated that CRA and FRA recombinant proteins, used for diagnosis of Chagas' disease, elicited a humoral immune response in susceptible and resistant mice. To understand better the immune response to these proteins, we have evaluated, the cellular immune response in CRA- and in FRA-immunized BALB/c and C57BL/6 mice. A specific cellular lymphoproliferative response was observed in both strains of mice. Spleen cell cultures mainly from CRA-immunized C57BL/6 and FRA-immunized BALB/c mice produced high levels of IFN-y, indicating the induction of a Type 1 immune response. Regarding the T cell subsets, CD4+ T cells were the major source of IFN-y in CRA- and FRA-immunized mice. These results suggest that CRA and FRA are important immunogens in inducing a Type 1 immune response and that they may be considered as potential vaccine antigens.

Animals↗

PubMed2001

The effect of monoclonal antibody and route of immunization on the humoral immune response against Porphyromonas gingivalis.

Immunomodulation mediated by exogenous antibodies has been proposed as a vaccine strategy to improve immune protection against pathogenic microorganisms and suggested to contribute to protection following passive immunization. To test whether a monoclonal antibody directed against an adhesion epitope of the periodontal pathogen Porphyromonas gingivalis could influence the humoral immune response following mucosal immunization, BALB/c mice were immunized orally or intranasally with P. gingivalis alone or P. gingivalis coated with monoclonal antibody 61BG1.3. Differences in antigenic specificity of anti- P. gingivalis serum immunoglobulin G (IgG) were demonstrated between groups of mice that received monoclonal antibody-coated P. gingivalis versus those that received P. gingivalis alone by either route of immunization. Binding of monoclonal antibody 61BG1.3 to P. gingivalis prior to immunization did not influence the serum IgG subclass distribution. However, minor differences in subclass distribution were observed between the various routes of mucosal immunization. These results support the hypothesis that specific monoclonal antibody bound to a bacterial vaccine can alter the quality of the humoral immune response to that organism.

Administration, Intranasal↗

PubMed2006

Termination of systemic immunity in the presence of intraocular tumors: influence of ocular immune privilege on tumor vaccines.

Ocular immune privilege preserves the visual axis by preventing the induction of sight-threatening nonspecific inflammation. Although privilege is essential for maintaining visual integrity, intraocular tumors exploit the privileged environment and grow progressively within the anterior chamber of the eye. Recently, a large number of laboratories have constructed genetically engineered tumor cell vaccines that express high levels of costimulatory signals. These vaccines are designed to bypass the normal pathways of T-cell activation and directly activate CD8+ tumor-specific T cells. In the following series of experiments, we determined whether a tumor cell vaccine that uses costimulatory signals (CD80 and IL-12) is capable of eliminating tumors within the immune-privileged anterior chamber. As expected, vaccine-immunized mice rejected subcutaneous flank tumors (a non-privileged site). However, the vaccine failed to protect mice from even a small number of tumor cells transplanted into the immune-privileged anterior chamber. Surprisingly, immunized mice that were simultaneously challenged with subcutaneous and anterior chamber tumors were unable to eliminate tumors at either site. The failure of systemic protective immunity coincided with the loss of tumor-specific delayed hypersensitivity and cytotoxic T cells. We conclude that tumor cell vaccines that induce complete protection against tumors in non-immune-privileged sites fail to protect against the same tumor within an ocular immune-privileged site. Moreover, a tumor that escapes elimination within the eye can terminate systemic protective immunity that is induced by the tumor cell vaccine.

Animals↗

PubMed2004

Pertussis-specific cell-mediated and humoral immunity in adolescents 3 years after booster immunization with acellular pertussis vaccine.

We evaluated pertussis-specific cell-mediated immunity (CMI) and humoral immunity in adolescents 3 years after they received an acellular pertussis booster immunization. Two hundred sixty-four adolescents were examined for immunoglobulin G antibodies, and 49 were examined for CMI against Bordetella pertussis antigens 40 months after receiving the booster. A control group of similarly aged adolescents who had received diphtheria and tetanus vaccination 3 years earlier was included for comparison. Pertussis-specific CMI persisted at greater than prebooster immunization levels. Although they had decreased by the 3-year follow-up, antibody levels remained significantly higher than prebooster immunization levels. Antibodies against pertussis antigens and CMI against filamentous hemagglutinin and pertactin were significantly higher in vaccinated adolescents than in control subjects. The acellular pertussis booster immunization provides long-term CMI and humoral immunity lasting for >or=3 years. The significantly higher immunity observed in the diphtheria, tetanus, and acellular pertussis vaccine recipients, compared with that in control subjects, indicates that these responses are more likely to have resulted from the booster immunization than from the boosting effects of natural B. pertussis infection.

Adolescent↗

PubMed2003

Intramuscular immunization with poliovirus replicons primes for a humoral and cellular immune response to soluble antigen.

Vaccines that stimulate both cellular and humoral immunity will probably be needed to control many infectious diseases. Previously, our laboratory generated a vaccine vector that uses poliovirus genomes (replicons) in which the capsid genes have been replaced by foreign proteins. In the current study, we have evaluated the immune responses induced by immunization using poliovirus replicons encoding green fluorescent protein (GFP). Although intramuscular administration of replicons resulted in GFP expression in the muscle, the levels of anti-GFP antibodies in serum were low compared to those of mice immunized with soluble, recombinant GFP (rGFP). Intramuscular booster immunization with rGFP in animals primed with replicons encoding GFP resulted in production of both serum IgG1 and IgG2a GFP-specific antibodies. The cells isolated from spleens of animals primed with replicons and boosted with rGFP secreted IFN-gamma after in vitro stimulation with rGFP. Intramuscular immunization of animals with a single dose of replicons encoding GFP followed by two intranasal applications of rGFP resulted in serum GFP-specific IgG1 and IgG2a isotypes, consistent with induction of both humoral and cellular responses. The results of this study establish that immunization with replicons followed by boost with soluble antigen, even at a different site, can generate a more diverse immune response compared with immunization regimen using soluble antigen alone. This strategy could be exploited for the development of new vaccine approaches against infectious diseases.

Administration, Intranasal↗

PubMed1976

Host immune responses after administration of inactivated Venezuelan equine encephalomyelitis virus vaccines. I. Description and characterization of adoptive transfer by immune spleen cells.

Cellular immune responses after immunization with a number of inactivated Venezuelan equine encephalomyelitis (VEE) virus vaccines were evaluated in mice by means of an adoptive transfer system. Formalin-inactivated, TC-83 strain VEE virus vaccine was immunogenic and highly effective in protecting recipient mice against challenge with virulent VEE virus. In contrast to immunization with live TC-83 VEE virus vaccine, however, immunization with inactivated VEE vaccine did not provide donor mice with the capacity to transfer adoptive immunity readily. Only when mice were immunized with inactivated VEE vaccine combined with specific adjuvants (particularly complete Freund's adjuvant or Bordetella pertussis) were donors capable of consistently transferring adoptive immunity. The total dose of inactivated VEE vaccine did not appear to influence the capacity to transfer adoptive immunity. On the other hand, weekly boosters of VEE vaccine and/or administration of vaccine with specific adjuvants did markedly influence donor immune responses.

Animals↗

PubMed1978

Significance of thymus-derived lymphocytes in immunity elicited by immunization with ribosomes or live yeast cells of Histoplasma capsulatum.

The lymphoid cells responsible for protective immunity to histoplasmosis were characterized. Adoptive transfer of spleen and peritoneal cells treated with antiserum to theta-antigen from mice immunized with ribosomes or live yeast cells of Histoplasma capsulatum abrogated the ability of these cells to protect the syngeneic recipients, whereas treatment of lymphoid cells with antiserum to IgG did not affect the immunity. Prior removal of glass-adhering cells from spleen and peritoneal cell suspensions did not alter their protective activity. Treatment with mitomycin C, an antimitotic agent, ablated the capacity of immune lymphocytes to protect the syngeneic recipients. These results indicate that the immune spleen and peritoneal cells that confer immunity to histoplasmosis are thymus-dependent (T) lymphocytes and that their active proliferation in the recipients is necessary for expression of the protective immunity. Furthermore, the immunity elicited by immunization with histoplasma ribosomes and live yeast cells is mediated by a similar mechanism.

Adhesiveness↗

PubMed1981

Local cellular immunity in the draining lymph nodes of mice after immunization with histocompatibility alloantigens.

Mice immunized with allogeneic cells exhibit a local component of cellular immunity that is confined to lymph nodes draining the site of immunization. After immunization of C3H mice by skin grafting or by i.p. or footpad injection of F1 hybrid spleen cells, draining lymph nodes show increased responsiveness toward the immunizing histocompatibility determinants for at least 3 months after immunization. This local component of immunity is not detected in a traditional graft-versus-host (GVH) assay of splenomegaly. To demonstrate this immunity, we used a GVH assay in which pieces of whole lymph nodes were grafted onto F1 hybrid host kidneys. The enlargement of each grafted node piece is taken as the measure of its immunological responsiveness. We interpret our results to indicate that this node-onto-kidney assay detects the contribution of a relatively immobile donor cell population that exerts its effects in lymph nodes local to, but not distant from, the site of immunization.

Animals↗

PubMed1997

Mucosal immunization with recombinant adenoviruses: induction of immunity and protection of cotton rats against respiratory bovine herpesvirus type 1 infection.

To facilitate the evaluation of vaccines against bovine herpesvirus type 1 (BHV-1), a cotton rat model of intranasal (i.n.) BHV-1 infection was established. Cotton rat lung cells were similar to bovine cells in their ability to support BHV-1 replication in vitro. Furthermore, i.n. inoculation of cotton rats with BHV-1 resulted in pulmonary lesions comparable to BHV-1 infection in cattle. Using this model, the potential of i.n. and gastrointestinal (g.i.) immunization was examined with recombinant human adenoviruses expressing glycoprotein D (gD) of BHV-1 to induce protective immunity against BHV-1. The replication-competent virus (gD-dE3) was more efficient than the replication-defective virus (gD-dE1E3) in inducing gD-specific antibody in the serum and in the respiratory tract. Furthermore, i.n. immunization with gD-dE3 stimulated antigen-specific antibody-secreting cells in the lung 12 weeks following immunization. Protection against BHV-1 challenge correlated with gD-specific antibody levels such that i.n. immunization with gD-dE3 conferred complete protection, while g.i. immunization conferred only partial protection of the lungs of most animals against BHV-1 challenge. In comparison, immunization with gD-dE1E3 by either route resulted in only a partial reduction of BHV-1 titre in the respiratory tract. The results obtained demonstrate that mucosal immunization with replication-competent recombinant adenovirus expressing gD of BHV-1 can induce immunity and protection against BHV-1 challenge.

Animals↗

PubMed2004

Modulation of immune responses to bovine herpesvirus-1 in cattle by immunization with a DNA vaccine encoding glycoprotein D as a fusion protein with bovine CD154.

The objective of this study was to determine whether a DNA vaccine encoding bovine CD154 linked to a truncated version of bovine herpesvirus-1 (BHV-1) glycoprotein D (tgD-CD154) induces enhanced tgD-specific immune responses in cattle. In vitro characterization demonstrated that tgD and tgD-CD154 both bind to cultured bovine B cells, whereas only tgD-CD154 induces interleukin-4-dependent proliferation, suggesting that tgD-CD154 specifically binds the CD40 receptor and induces receptor signalling. Calves were immunized with plasmid encoding either tgD or tgD-CD154 by intradermal injection with a needle-free device. After two immunizations, tgD-specific immune responses were observed in both vaccinated groups and after challenge with BHV-1 these responses further increased. Animals immunized with plasmid encoding tgD-CD154 had significantly higher tgD-specific serum titres of immunoglobulins G and A but significantly lower numbers of tgD-specific interferon-gamma-secreting cells than animals immunized with plasmid encoding tgD after BHV-1 challenge. This suggests that the expression of an antigen as a chimeric protein with CD154 can qualitatively alter immune responses in cattle. Since we previously showed that plasmid encoding tgD-CD154 induces significantly enhanced secondary tgD-specific antibody responses in sheep, there appear to be interspecies differences in the immune responses induced by tgD-CD154, which suggests that both proteins in the chimeric molecule may influence protein targeting and the induction of an immune response.

Animals↗

PubMed1992

Immunization status of casualty attenders: risk factors for non-compliance and attitudes to 'on the spot' immunization.

Outbreaks of vaccine preventable infections have focused attention on 'missed opportunities' for immunizing children. The immunization status of 520 consecutive children attending Casualty during a 10 day period was studied. Only 70% of children had received their diphtheria, tetanus, pertussis (DTP) and poliomyelitis immunization at the appropriate time, 13% had completed the schedule later than recommended and 17% had immunizations overdue by 4 weeks or more. For measles (mumps/rubella) vaccine (MM or MMR) 75% were up to date, 10% were given late and 15% were overdue. A subset of 171 families was interviewed to evaluate factors affecting compliance. Families possessing a Social Security 'Health Care Card', whose father was unemployed, who spoke poor English or who had lived in Australia for 5 years or less were significantly more likely (P < 0.02) to be inadequately immunized. There were 84 children whose immunization was overdue and who were well enough to be immunized. The parents of 70 (83%) of these 84 said that they would agree to 'on the spot' immunization if it were available; 14 (17%) parents refused, the commonest reason for refusal being that the parents felt that the child was too sick at the time to be immunized.

Child↗