Dual effect of meningococcal antigens on a T cell dependent immune response

Meningococcal antigens (MA) showed adjuvant activity when administered to mice at the same time as antigen (sheep erythrocyte (SE], by increasing the splenocyte plaque-forming response in a dose-related manner. However, when SE were given 1 day after MA administration, the subsequent plaque formation was diminished from normal in proportion to the dose of MA injected. Splenocytes taken from mice up to 5 days after MA injection actively inhibited plaque formation when mixed with splenocytes immunized with SE 4 days earlier. Two days after MA injection the nonspecific inhibition of plaque formation was mainly due to adherent spleen cells, while at 5 days nonadherent cells had acquired the inhibitory activity. It appears that it is the degree of activation of adherent cells resulting from the timing and dosage of MA which modulates the subsequent development and secretion of antibody-forming cells.     

Primary and secondary immune response of mice to polysaccharide antigens of meningococcal serogroups A and C

The peculiarities of the primary immune response, the formation of immunological memory and the secondary immune response to serogroup A and C meningococcal polysaccharides were studied in 7 strains of inbred mice, hybrids F1 and in noninbred animals. The passive local hemolysis test and the passive hemagglutination test indicated that the intensity of immune response to A and C polysacchardies depended on the genotype of the animals: both antigens induced the most intense response in CBA and BALB/c mice. The primary immune response to the both antigens was characterized by a short latent period, a rapid (by days 4-5) increase in the amount of antibody-producing cells in the spleen and in antibody titer in the blood serum to the maximum level, and a pronounced decrease inantibody formation by days 6-7 followed by a gradual extinction of the response. A single injection of A and C polysaccharides in a dose of 0.5 microgram induced the formation of immunological memory in mice, persisting for at least 4 weeks and manifesting after reimmunization as the increased or more prolonged synthesis of IgM and IgG.     

Directing the immune response to carbohydrate antigens

Peptide mimetics may substitute for carbohydrate antigens in vaccine design applications. At present, the structural and immunological aspects of antigenic mimicry, which translate into immunologic mimicry, as well as the functional correlates of each, are unknown. In contrast to screening peptide display libraries, we demonstrate the feasibility of a structure-assisted vaccine design approach to identify functional mimeotopes. By using concanavalin A (ConA), as a recognition template, peptide mimetics reactive with ConA were identified. Designed peptides were observed to compete with synthetic carbohydrate probes for ConA binding, as demonstrated by enzyme-linked immunosorbent assay and isothermal titration calorimetry (ITC) analysis. ITC measurements indicate that a multivalent form of one particular mimetic binds to ConA with similar affinity as does trimannoside. Splenocytes from mimeotope-immunized mice display a peptide-specific cellular response, confirming a T-cell-dependent nature for the mimetic. As ConA binds to the Envelope protein of the human immunodeficiency virus, type 1 (HIV-1), we observed that mimeotope-induced serum also binds to HIV-1-infected cells, as assessed by flow cytometry, and could neutralize T-cell line adapted HIV-1 isolates in vitro, albeit at low titers. These studies emphasize that mimicry is based more upon functional rather than structural determinants that regulate mimeotope-induced T-dependent antibody responses to polysaccharide and emphasize that rational approaches can be employed to develop further vaccine candidates.     

Humoral immune response to filarial antigens in chyluria

Humoral immune parameters like total immunoglobulins and specific antibody levels in serum were studied in filarial chyluria patients. Mean serum IgG was significantly reduced in this group compared to normal controls, while IgA and IgM levels remained comparable to controls. Anti-filarial antibody titre as measured by enzyme-linked immunosorbent assay also was significantly reduced. However, the total and specific IgE antibody titre was similar to that of controls. Specific IgE contents of the patients’ sera could be related to their microfilaraemic status.     

Computational modeling of the immune response to tumor antigens

Vaccination protocols designed to elicit anti-cancer immune responses have, many times, failed in producing tumor eradication and in prolonging patient survival. Usually in cancer vaccination, epitopes from one organism are included in the genome or linked with some protein of another in the hope that the immunogenic properties of the latter will boost an immune response to the former. However, recent results have demonstrated that injections of two different vectors encoding the same recombinant antigen generate high levels of specific immunity. Systematic comparison of the efficacy of different vaccination protocols has been hampered by technical limitations, and clear evidence that the use of multiple vectors has advantages over single carrier injections is lacking. We used a computational model to investigate the dynamics of the immune response to different anti-cancer vaccines based on randomly generated antigen/carrier compounds. The computer model was adapted for simulations to this new area in immunology research and carefully validated to the purpose. As a matter of fact, it reproduces a relevant number of experimental observations. The model shows that when priming and boosting with the same construct, competition rather than cooperation develops amongst T cell clones of different specificities. Moreover, from the simulations, it appears that the sequential use of multiple carriers may generate more robust anti-tumor immune responses and may lead to effective tumor eradication in a higher percentage of cases. Our results provide a rational background for the design of novel strategies for the achievement of immune control of cancer.     

IL-13 regulates the immune response to inhaled antigens

The large inhibitory effect of IL-13 blockers on the asthma phenotype prompted us to ask whether IL-13 would play a role in regulating the allergic immune response in addition to its documented effects on structural pulmonary cells. Because IL-13 does not interact with murine T or B cells, but with monocytes, macrophages, and dendritic cells (DCs), we examined the role of IL-13 in the activation of pulmonary macrophages and DCs and in the priming of an immune response to a harmless, inhaled Ag. We found that a majority of cells called "alveolar or interstitial macrophages" express CD11c at high levels (CD11c(high)) and are a mixture of at least two cell types as follows: 1) cells of a mixed phenotype expressing DC and macrophage markers (CD11c, CD205, and F4/80) but little MHC class II (MHC II); and 2) DC-like cells expressing CD11c, CD205, MHC II, and costimulatory molecules. Endogenous IL-13 was necessary to induce and sustain the increase in MHC II and CD40 expression by pulmonary CD11c(high) cells, demonstrated by giving an IL-13 inhibitor as a measure of prevention or reversal to allergen-primed and -challenged mice. Conversely, IL-13 given by inhalation to naive mice increased the expression of MHC II and costimulatory molecules by CD11c(high) cells in an IL-4Ralpha-dependent manner. We found that exogenous IL-13 exaggerated the immune and inflammatory responses to an inhaled, harmless Ag, whereas endogenous IL-13 was necessary for the priming of naive mice with an inhaled, harmless Ag. These data indicate that blockade of IL-13 may have therapeutic potential for controlling the immune response to inhaled Ags.     

Cell-mediated immune response of marmosets to herpesvirus-associated antigens in vitro

Summary Immune responses in vitro of some species of marmosets to herpesvirus-associated antigens expressed on virus-transformed lymphoblastoid cell lines (LCL) were studied by determining lymphocyte proliferation, interferon production, and the induction of cytotoxic effector cells in mixed lymphocyte-LCL cultures (MLLC). Autologous Epstein-Barr virus (EBV)-transformed B-cell lines induced neither lymphocyte proliferation nor interferon production in MLLC, while autologous Herpesvirus ateles (HVA)-transformed T-cell lines stimulated responder cell DNA synthesis and interferon production. Both EBV-LCL and HVA-LCL failed to induce cytotoxic effector cells in autologous MLLC responder cells. These findings differ markedly from the human immune response to autologous EBV-LCL in vitro and may have implications for the unusual susceptibility of marmosets to the induction of lymphoproliferative disease following inoculation with oncogenic herpesviruses.     

Characterization of the immune response to Leishmania infantum recombinant antigens

Leishmaniases have a high prevalence in tropical countries. In order to improve existing diagnostic systems based on total Leishmania proteins, and to identify antigen candidates for vaccine development, an intensive search for the identification of antigens was performed using molecular biology techniques. In this study, the immune response to three L. infantum recombinant antigens was evaluated. Upon stimulation with KMP11, mononuclear cells from leishmaniasis patients produced high levels of IL-10, while a predominant IFN-gamma production could be observed in cultures stimulated with H2A and soluble Leishmania antigen. All the recombinant antigens induced very little IL-5. KMP11 decreased IFN-gamma production by 48% in cultures of peripheral blood mononuclear cells from cutaneous leishmaniasis patients who had been stimulated with soluble Leishmania antigen. Furthermore, antibodies to KMP11 were detected in the sera from all patients with visceral leishmaniasis and in the majority of the sera from patients with cutaneous leishmaniasis or individuals with asymptomatic L. chagasi infection. Thus, KMP11 is recognized by cells and sera of patients with different clinical forms of leishmaniasis, and KMP11, through IL-10 production, proved to be a potent antigen in modulating type 1 immune response.     

Induction of the immune response to cell surface antigens in vitro

Summary Two tissue culture incubation systems are described in which immune responses to cell surface antigens have been demonstrated In the one-way “mixed lymphocyte interaction” system, a specific stimulation of thymidine uptake was induced by a particulate membrane antigen fraction, the microsomal lipoproteins (MLP)when low levels (0.01 to 0.001 μg per ml) were incubated with spleen or lymph node cells from nonsensitized mice. No stimulation was seen when allogeneic MLP was used at high levels, 10 μg per ml, nor at any level with syngeneic MLP. Specific effectors were demonstrated after 72-hr incubation with stimulatory levels of allogeneic MLP in three separate in vitro assays, a plaque-forming cell reduction assay, a tumor target assay, and an antigen-binding cell assay. In the latter assay, [¹²⁵I]MLP was used as the source of antigen. This system has limited potential inasmuch as mouse spleen cells do not survive in it beyond the 4th day of culture. The second tissue culture system, the Marbrook system, has much greater possibilities because at least 25% of the inoculum is recovered 7days later. In this culture system a cell-free sheep erythrocyte membrane preparation can induce, plaque-forming cells in the absence of macrophages. Using a sensitive radioimmunoassay, frees specific antibody was detected in culture supernatant fluids. With the same culture system, allogeneic lymphocytotoxic cells (killer) have been induced with spleen cells from unprimed mice in strains differing at the major histocompatibility locus (H-2). Allogeneic MLP induced very significant “killer” cell activity with spleen cells from primed mice. In a syngeneic tumor systems, significant amounts of killer cell activity were induced with unprimed spleen cell inocula, and much larger amounts induced with spleen cells from immunized mice. Presented in the formal symposium on Carcinogenesis in Vitro, at the 25th Annual Meeting of the Tissue Culture Association, Miami Beach, Florida, June 3–6, 1974. This work was supported by Public Health Service Rescarch grants CA 07973 and CA 10815 from the National Cancer Institute.     

The genetic control of the immune response to murine histocompatibility antigens

The genetic control of the immune response to H-4 histocompatibility alloantigens is described. The rejection of H-4.2-incompatible skin grafts is regulated by anH-2-linkedIr gene. Fast responsiveness is determined by a dominant allele at theIrH-4.2 locus. TheH-2 ^b ,H-2 ^d , andH-2 ^s haplotypes share the fast response allele;H-2 ^a has the slow response allele. Through the use of intra-H-2 recombinants, we have mapped theIrH-4.2 locus to theI-B subregion of theH-2 complex; theH-2 ^h4 ,H-2 ¹⁵, andH-2 ^t4 haplotypes are fast responder haplotypes. These observations suggest that the strength of non-H-2 histocompatibility antigens is ultimately determined by the antigen-specific recipient responsiveness.