Effect of radiation-induced bystander chemosignals of mice on the humoral immune response in spleen and lymph nodes of intact recipients

The ability of post-radiation (4 Gy) bystander chemosignals (the volatile components of mouse urine) to distantly modulate the humoral immune response to the sheep red blood cells in the spleen and popliteal lymph nodes of intact recipients has been investigated. It was shown that the exposure of animals to chemosignals before antigen injection resulted in the decrease and increase of the immune response in the spleen and lymph nodes, respectively. When animals were exposed to chemosignals after the antigenic stimulus, an increased immune response was observed in both spleen and lymph nodes. The contribution of radiation-induced bystander signaling in the response of socially organized animals to the effect of ionizing irradiation is discussed.     

Immunoregulation by antigen/antibody complexes. I. Specific immunosuppression induced in vivo with immune complexes formed in antibody excess

Specific immune complexes, prepared at different ratios of antibody to antigen, were examined for their effects on the antibody response of BALB/c mice to the cell wall polysaccharide antigen (PnC) extracted from Streptococcus pneumonia R36a. Mice immunized with complexes formed in antigen excess developed a PnC-specific antibody response that was equivalent to that in mice injected with free antigen. On the other hand, mice injected with complexes formed in antibody excess developed very little PnC-specific antibody. Furthermore, administration of immune complexes (formed in antibody excess) resulted in suppression of the response to an immunogenic dose of PnC given concurrently or 1 day after injection of immune complexes but not when the antigen was given 1 day before injection of the immune complexes. Injections of free antibody (TEPC-15) also resulted in suppression of the response to antigenic challenge; however, suppression was greatest when the antibody was injected concurrently with the antigen, suggesting that the suppression was mediated through the formation of immune complexes in vivo. The suppression appears to be specific for the antigen (PnC), since in mice injected with TEPC-15/PnC complexes (formed in antibody excess) and challenged with PnC coupled to sheep RBC, only the response to PnC was suppressed.     

"Cross-wiring" of the immune response in old mice: increased autoantibody response despite reduced antibody response to nominal antigen

Older humans and experimental animals have been repeatedly found to have higher titers of autoantibodies than do younger individuals despite the impaired responses of older individuals to foreign antigens. The studies reported here were designed to examine the relationship between these two age-related changes in antibody responses. Antibody response to foreign antigen was measured concurrently with autoantibody response in the same mice. Old mice (18-24 months old) had decreased responses to foreign antigens and increased responses to bromelain-treated syngeneic erythrocytes, compared to young mice (2 months old). In vitro mixing experiments were consistent with the possibility that suppressor cell activity in spleen cells from old mice reduce the antibody response to foreign antigen but not to autologous antigen. The results support an emerging view that age-associated changes in immune responses are the result of dysregulation rather than exhaustion of the immune system.     

Slight influence of the estrous cycle stage on the mucosal and systemic specific antibody response induced after vaginal and intraperitoneal immunization with protoxin Cry1Ac from Bacillus thuringiensis in mice

Since the immune response appears to be variable according to the hormonal stage of the mammalian female, the aim of this study was to determine whether estrous cycle stage modifies the mucosal and systemic immune responses induced by intraperitoneal and vaginal immunization of mice with protoxin Cry1Ac. We tested the influence of three immunizations on the specific antibody response elicited at estrus and diestrus, that were the same estrous cycle stages at which the antigen was applied. Both intraperitoneal and vaginal immunization of mice with Cry1Ac either at estrus or diestrus induces specific antibody responses at serum, vagina and large intestine. The stage of the estrous cycle have little or non influence in the magnitude of the response induced, since only at serum the IgM was slightly higher at estrus than at diestrus by both routes. At the large intestine only the IgA response elicited via the intraperitoneal route changed, being higher at diestrus, whereas at the vagina IgA response induced did not change significantly due to the cycle stage. Present results suggest that Cry1Ac may be used as an antigen carrier as it can elicit antibody responses at systemic level and at several mucosal sites including the vagina that are not modified significantly throughout the reproductive cycle.     

Idiotype-restricted antibody response to specific immune complexes

In this report, we compared the immunogenicity of specific antigen/antibody complexes with that of free antigen. The complexes were prepared in antigen excess using the TEPC-15 myeloma protein and a phosphorylcholine-containing polysaccharide antigen (PnC), and the PnC-specific antibody response was measured using a hemolytic plaque assay 5 days after immunization. The results showed that the complexes were as immunogenic as the free antigen; however, the PnC-specific antibody response induced with the complexes was completely dominated by one particular idiotope (defined by plaque inhibition with the AB1-2 monoclonal antibody). On the other hand, the response of mice immunized with free antigen (PnC) was dominated to a lesser degree by the AB1-2 idiotope, and there was a great degree of variability in idiotope expression among individual mice. The results suggest that immunization with antigen/antibody complexes restricts the response to the expression of idiotopes that are present in the immune complex.     

Transition in the Character of Immunological Memory in Mice after Immunization

The immunological memory in antibody response of mice to bovine serum albumin was investigated at the level of IgM and IgG antibody-forming cells. The antigen at a dose much lower than required for eliciting a detectable level of the primary antibody response could latently activate the immune machinery to an extent adequate for specific recall, whereas higher doses of antigen were effective in evoking strong anamnestic response. The potentiality to develop the anamnestic response was found even in the latent phase of the primary antibody response and was maintained for more than 2 months. The immunological memory acquired in an early phase after the primary immunization mainly involved IgM antibody response and late memory concerned IgG response.     

Role of L-lysine HCl in adoptive immune therapy towards development of suitable tuberculosis vaccination

L-Lysine HCI is being proposed to be a possible biocompatible adjuvant to enhance immune response by virtue of its probable non-specific bridging action and cellular proliferation properties. This proposal has been tried to be substantiated by designing an in vitro culture protocol, varying the concentration of L-lysine HCI and its further in vivo application. Splenic lymphocyte population has been extracted from mice and co-cultured with extracted mice macrophage population in presence of either Bacille Calmette Guerrin (BCG) or Hepatitis B surface antigen (HbsAg) and added L-lysine hydrochloride in culture media. Post incubation of these cultures, "taught" cell population has been adoptively transferred in na?ve mice. These mice were then challenged by respective antigen dose, Change in Immune response with this challenge was noted. Antibody titre was followed in all the experiments as a measure of immune response. In adoptive immune transfer experiment of with HbsAg (AIT-HbsAg), similar to that with BCG (AIT-BCG), after the incubation period, antibody titre was higher in added lysine containing cultures in comparison with the control ones. Post transfer followed by antigen challenge, in AIT-BCG the expected augmentation in immune response was hardly visible. But in AIT-HbsAg, with the help of lysine booster, the animals responded better as far as the antibody titre is concerned.     

Immunological memory is compromised by food restriction in deer mice Peromyscus maniculatus

The immune system protects organisms against infection, but this protection presumably comes at a cost. Here, we asked whether food restriction would compromise the ability of an organism to generate an immune response on reexposure to an antigen, which would represent a functional cost of immunological memory. Immunological memory is generated when B and T lymphocytes sensitive to components of pathogens (i.e., antigens) proliferate after exposure and persist in circulation to hinder reinfection. To test the possibility that B cell memory, the component of the immune system responsible for antibody production, is expensive to maintain, secondary antibody production against a novel protein [keyhole limpet hemocyanin (KLH)] was compared in food-restricted and ad libitum-fed male deer mice (Peromyscus maniculatus). To determine whether compromised secondary antibody production was solely due to elevated corticosterone independent of resource availability, some food-restricted and ad libitum-fed mice were subjected to unpredictable, chronic (2 h/day) restraint. Mice fed 70% of their ad libitum diet 2 wk after primary antigen challenge produced approximately 95% less IgG against KLH after a second antigen challenge than mice fed ad libitum, even though all mice were fed ad libitum during the secondary antibody response period. Restraint had no effect on secondary IgG production in response to KLH, and corticosterone concentrations 1 day after food restriction did not differ between food-restricted and ad libitum-fed mice. Together, these data imply that secondary antibody responses and the benefits of immunological memory are energetically costly in this species.     

Exposure to Factor VIII Protein in the Presence of Phosphatidylserine Induces Hypo-responsiveness toward Factor VIII Challenge in Hemophilia A Mice

Administration of recombinant factor VIII (FVIII), an important co-factor in blood clotting cascade, elicits unwanted anti-FVIII antibodies in hemophilia A (HA) patients. Previously, FVIII associated with phosphatidylserine (PS) showed significant reduction in the anti-FVIII antibody response in HA mice. The reduction in the immune response to FVIII-PS could be due either to a failure of the immune system to recognize the antigen (i.e. immunological ignorance) or to an active induction of an antigen-specific nonresponsiveness (i.e. immunological tolerance). If it were a result of tolerance, one would predict that pre-exposure to FVIII-PS would render the mice hypo-responsive to a subsequent FVIII challenge. Here, we have demonstrated that naive HA mice that were pretreated with FVIII-PS showed a significantly reduced FVIII immune response to further challenge with native FVIII and that this decreased responsiveness could be adoptively transferred to other mice. An increase in number of FoxP3-expressing CD4⁺ regulatory T-cells (Treg) was observed for the FVIII-PS-immunized group as compared with animals that received FVIII alone, suggesting the involvement of Treg in PS-mediated hypo-responsiveness. The PS-mediated reduction in antibody response was reversed by the co-administration of function-blocking anti-TGF-β antibody with FVIII-PS. The decreased response to FVIII induced by FVIII-PS was determined to be antigen-specific because the immune response to another non-cross-reactive antigen (ovalbumin) was not altered. These results are consistent with the notion that FVIII-PS is tolerogenic and suggest that immunization with this tolerogenic form of the protein could be a useful treatment option to minimize immunogenicity of FVIII and other protein-based therapeutics.     

Removal of glomerular deposits induced by either preformed immune complexes or by a chronic immune complex model in NZB/W mice

The solubilization and removal of defined glomerular immune complex deposits by excess antigen was examined in NZB/W female mice. Glomerular deposits were induced by administering preformed immune complexes to young (2 to 4 mo) mice before they naturally acquired deposits from endogenous disease and to old (7 mo) mice with deposits from naturally acquired disease. The administration of excess antigen specifically removed deposits of preformed immune complexes in both groups. This was associated with a reduction in circulating large latticed complexes containing more than two antigen and two antibody molecules (greater than Ag2Ab2). Established deposits in old mice therefore did not interfere with removal of newly induced deposits of preformed immune complexes. Glomerular deposits were also induced in young mice by a chronic human serum albumin (HSA) immune complex model. The antigen in immune deposits induced by 2 wk of chronic antigen administration was solubilized and was removed within 48 hr of administering excess antigen. Circulating antibodies to the antigen were also reduced by excess antigen. Glomerular deposits of mouse immunoglobulin and complement were not significantly reduced by excess antigen but remained more intense than in mice of comparable age given preformed complexes. Thus deposits of other antigen antibody systems and possibly endogenous disease were induced by the chronic HSA immune complex model in NZB/W mice. However, defined antigen deposits within deposits containing multiple antigen antibody systems can clearly be removed by administering excess antigen.     

Immunogenicity is unrelated to protective immunity when induced by soluble and particulate antigens from Nocardia brasiliensis in BALB/c mice

Cell-mediated immunity plays a major role in protection against intracellular microbes. Nocardia brasiliensis is a facultative intracellular pathogen that causes chronic actinomycetoma. In this work, we injected BALB/c mice with soluble P24 and particulate antigens from N. brasiliensis. A higher antibody titer and lymphocyte proliferation was induced by the particulate antigen than by the soluble antigen. However, five months after antigen injection, antibody concentration and lymphocyte proliferation were similar. An increase in CD45R and CD4 T cells was unrelated to protective immunity. Active immunization with soluble or particulate antigens induced complete protection during the primary immune response. This protective response was IgM mediated. The higher immunogenicity was not related to protective immunity since the particulate antigen induced protection similar to the soluble antigen. Using particulate antigens for vaccination guarantees a stronger immune response, local and systemic side effects, but not necessarily protection.     

乙肝病毒核心蛋白病毒样颗粒表面抗原密度对抗体应答水平的影响

【目的】为了探究乙肝病毒核心蛋白(HepatitisBviruscoreprotein,HBc)病毒样颗粒(Virus-like particles,VLPs)表面抗原密度对免疫后抗体应答水平的影响,制备了不同抗原密度的HBc VLPs疫苗,并检测了其在小鼠体内的抗体应答水平。【方法】首先制备了N端带有3个甘氨酸的人巨细胞病毒重组抗原域AD-4作为模式抗原,接着通过Sortase A的介导将AD-4连接到HBc VLPs表面上。将系列浓度梯度AD-4抗原在SortaseA介导下分别与相同浓度的HBcVLPs发生反应,制备不同抗原密度的HBc-AD-4 VLPs。将其分别免疫6–8周龄BALB/c小鼠3次,每次免疫间隔2 w,间接ELISA法检测被免疫小鼠血清的抗体应答水平。【结果】结果表明,当HBc VLPs表面抗原密度为44.4%时,即HBc反应浓度∶AD-4反应浓度为1:0.5时,不足以引起高滴度的抗体产生;当HBc VLPs表面抗原密度为64.2%时,即HBc反应浓度∶AD-4反应浓度为1:1时,HBc-AD-4 VLPs诱导的AD-4特异性抗体滴度与100%抗原密度的HBc-AD-4VLPs所引起的抗体滴度相当;当HBcVLPs表面抗原密度大于64.2%时,引起的抗体应答水平不因抗原密度增加而进一步增强。【结论】发现了HBcVLPs表面抗原密度与免疫后抗体滴度呈正相关,然而免疫64.2%抗原密度的HBc VLPs所产生的抗体滴度可达峰值,抗原密度进一步增加,抗体应答水平不会进一步加强。     

Trypanosoma cruzi: involvement of IgG isotypes in the parasitemia control of mice immunized with parasite exoantigens of isoelectric point 4.5.

In a previous work we demonstrated that Trypanosoma cruzi exoantigens of pI 4.5 (Ea 4.5), whose most important epitopes are glucidic, are able to induce a partially protective immune response in mice. To ascertain the involvement of antibody isotypes in this protection, we immunized mice with Ea 4.5 plus Bordetella pertussis as adjuvant. The analysis of immune response by skin test revealed the occurrence of specific immediate type hypersensitivity on Day 15 after the last immunization. By ELISA and using Ea 4.5 as antigen, specific IgG1 antibody was detected. When formaldehyde-fixed epimastigotes were used as antigen, binding of IgG1 and IgG2 was observed. Trypomastigotes incubated for 1 hr at 33 degrees C with the immune sera and then injected in normal syngeneic mice produced a significantly lower parasitemia than trypomastigotes incubated with the control sera. This capacity of anti-Ea 4.5 sera was resistant to 56 degrees C for 2 hr and was diminished after the absorption of immune sera with the carbohydrate moiety of Ea 4.5. The assay with the immune IgG1 and IgG2, separated through protein A-Sepharose affinity chromatography, showed that IgG1 retains most of this capacity. Purified immune IgG1 revealed two antigenic bands of molecular weight between 50 and 55 kDa in SDS-PAGE of Ea 4.5.     

FcRn overexpression in mice results in potent humoral response against weakly immunogenic antigen

The neonatal Fc receptor (FcRn) regulates IgG and albumin homeostasis, mediates maternal IgG transport, is active in phagocytosis and delivers antigen for presentation. We have previously shown that transgenic (tg) mice that have been created to overexpress bovine FcRn (bFcRn) demonstrate increased half-life of mouse IgG, significantly increased antigen-specific IgG in serum and augmented expansion of antigen-specific B cells and plasma cells after immunization. One of the interesting questions surrounding this enhanced immune response is whether these tg mice could effectively induce immune response to weakly immunogenic antigens. To address this question, we immunized these bFcRn tg mice with a conserved hemagglutinin subunit 2 (HA2)-based synthetic peptide that was recently found to be effectively targeted by neutralizing antibodies. Using an ELISA system, we found that, whereas wild-type mice showed a weak immune response and developed only a de minimis amount of antibody against the epitope, FcRn overexpressing animals mounted a robust reaction expressed in specific antibody titers on day 28 that continued to rise through day 50. Consistent with our previous data, the enhanced immune response resulting from the FcRn overexpression was also associated with a substantial increase in the number of spleen derived B cells, dendritic cells, granulocytes and plasma cells. Based on this evidence, we propose that tg mice that overexpress bFcRn offer major advantages in monoclonal antibody production because the tg mice would allow the generation of antibodies (hybridomas) to weakly immunogenic antigens that otherwise would be difficult or even impossible to make.Key words: neonatal Fc receptor (FcRn), transgenic mouse, immunogenicity, monoclonal antibody, influenza     

Immune responses of mice to influenza subunit vaccine in combination with CIA07 as an adjuvant

CIA07 is an immunostimulatory agent composed of E. coli DNA fragments and modified LPS lacking the lipid A moiety. In this study, we investigated whether CIA07 promotes immune responses as an adjuvant to the influenza subunit vaccine. Balb/c mice were immunized intramuscularly once or twice at a 4-week interval with the trivalent influenza subunit vaccine antigen alone or in combination with CIA07 as adjuvant. Antigen-specific serum antibody titers and hemagglutination-inhibition (HI) antibody titers were assessed. At 4 weeks after each immunization, the antigen-specific total serum IgG antibody titer in mice receiving CIA07 was 2 to 3 times higher than that in animals administered antigen alone (P<0.05). The CIA07-treated group additionally displayed higher HI antibody titers against each of the 3 vaccine strains, compared to the antigen group. Animals receiving antigen alone displayed barely detectable antigen-specific serum IgG2a antibody titers. In contrast, coadministration of CIA07 with antigen led to significantly enhanced IgG2a antibody responses, suggesting that CIA07 stimulates a Th1-type immune response. Moreover, the CIA07-treated group displayed a marked increase in the number of interferon gamma-producing CD8(+) T cells in splenocytes. These data collectively demonstrate that CIA07 has the ability to induce both Th1-type cellular and Th2-type humoral immune responses to the influenza subunit vaccine, and support its potential as an effective adjuvant to the influenza vaccine.     

FcRn overexpression in mice results in potent humoral response against weakly immunogenic antigen

The neonatal Fc receptor (FcRn) regulates IgG and albumin homeostasis, mediates maternal IgG transport, is active in phagocytosis and delivers antigen for presentation. We have previously shown that transgenic (tg) mice that have been created to overexpress bovine FcRn (bFcRn) demonstrate increased half-life of mouse IgG, significantly increased antigen-specific IgG in serum and augmented expansion of antigen-specific B cells and plasma cells after immunization. One of the interesting questions surrounding this enhanced immune response is whether these tg mice could effectively induce immune response to weakly immunogenic antigens. To address this question, we immunized these bFcRn tg mice with a conserved hemagglutinin subunit 2 (HA2)-based synthetic peptide that was recently found to be effectively targeted by neutralizing antibodies. Using an ELISA system, we found that, whereas wild-type mice showed a weak immune response and developed only a de minimis amount of antibody against the epitope, FcRn over-expressing animals mounted a robust reaction expressed in specific antibody titers on day 28 that continued to rise through day 50. Consistent with our previous data, the enhanced immune response resulting from the FcRn overexpression was also associated with a substantial increase in the number of spleen derived B cells, dendritic cells, granulocytes and plasma cells. Based on this evidence, we propose that tg mice that overexpress bFcRn offer major advantages in monoclonal antibody production because the tg mice would allow the generation of antibodies (hybridomas) to weakly immunogenic antigens that otherwise would be difficult or even impossible to make.     

Enhancement of reaginic and hemagglutinating antibody production by an extract of Bordetella pertussis containing histamine sensitizing factor.

The effect of an extract containing the histamine-sensitizing factor (HSF) of Bordetella pertussis on the immune response of mice to ovalbumin was investigated with respect to dose of antigen and adjuvant. Of particular interest was the enhancement of reaginic antibody production. In comparison to the Al(OH)3 induced production of reaginic antibody where low doses of antigen and adjuvant yield high titers of reagin, the HSF extract demonstrated optimal adjuvant activity at high doses of both adjuvant and antigen. The reaginic antibody response was maximal usually by 2 to 3 weeks post-immunization and persisted for long periods of time. The hemagglutinating antibody response was maximal at 8 to 10 weeks post-immunization. The initial treatment of mice with HSF extract plus antigen resulted in the production of memory cells since a subsequent immunization with ovalbumin alone evoked a secondary reaginic response. These observations may have implications in clinical allergy since substances similar to the pertussis factor might be produced by other microbial organisms and these substances could modulate the immunologic response of individuals to common allergens.     

Control of IgE and IgG1 antibody production in mice.

The production of IgE and IgG1 was studied in untreated, thymectomized. splenectomized, anti-thymocyte serum-treated, or sublethally X-irradiated mice. Dinitrophenyl Ascaris and ovalbumin were used as antigens, and aluminum hydroxide was used as adjuvant. A suppression of IgE production was observed in adult thymectomized mice, although the kinetic pattern of the antibody response was the same as in control animals. IgG1 antibody production was not affected by thymectomy. Splenectomy did not change either IgE or IgG1 production. A single dose of rabbit anti-thymocyte serum (ATS) given 8 days after immunization inhibited IgE antibody production. The effect of ATS was dose dependent and also varied with the amount of antigen used, the immune response to high doses being more susceptible to the effect of ATS. No alteration in IgG1 production was caused by ATS even when IgE antibody formation was completely inhibited. When preceding immunization, sublethal irradiation enhanced IgE antibody formation and partially suppressed IgG1 production; applied after immunization, irradiation caused an enhancement of IgE production which was inversely proportional to the interval elapsed between the two procedures. On the other hand, the IgG1 antibody production was fairly resistant to the same treatment. The results suggest a clearcut separation between the mechanisms regulating IgE and IgG1 production in mice.     

Immunization with native surface protein NcSRS2 induces a Th2 immune response and reduces congenital Neospora caninum transmission in mice

NcSRS2, a tachyzoite surface protein of Neospora caninum, is an immunodominant protein with respect to induction of antibody production and has a role in attachment and invasion of host cells. Native NcSRS2 was isolated from whole tachyzoite lysate antigen by affinity chromatography using NcSRS2 specific monoclonal antibody and used to immunize BALB/c mice in a congenital transmission study. NcSRS2 was a highly conserved protein as indicated by comparison of deduced amino acid sequence obtained from NcSRS2 gene sequences of 10 geographically distinct N. caninum isolates. Mice immunized with purified native NcSRS2 produced antigen-specific antibody, primarily of IgG 1 subtype. Following challenge during gestation with 10(7) tachyzoites, immunized mice had a statistically significant decreased frequency of congenital transmission compared to non-immunized mice (P相似文献   

Enhanced antibody response in retrovirus-infected mice treated with endotoxin or nontoxic polysaccharide derivative

Friend leukemia virus (FLV) is a retrovirus which causes marked suppression of the immune response of genetically susceptible mice. In the present study the depressed antibody response to sheep erythrocytes by spleen cells from FLV-infected mice was partially reversed by injection of either a bacterial endotoxin or a nontoxic polysaccharide derivative directly into infected mice or by addition to spleen cell cultures from these mice immunized in vitro with sheep red blood cells (SRBC). The endotoxin and PS in a dose-related manner markedly increased the antibody responsiveness of the spleen cells to SRBC. Thus these results indicate that the nontoxic polysaccharide derivative has properties equivalent to the toxic endotoxin in enhancing the antibody responsiveness of FLV-suppressed spleen cells to a T-cell-dependent antigen like SRBC.