Proliferative Response Of Splenocytes Research Articles

Immune responses of chickens inoculated with a recombinant fowlpox vaccine coexpressing HA of H9N2 avain influenza virus and chicken IL-18

Control of the circulation of H9N2 avian influenza virus (AIV) is a major concern for both animal and public health, and H9N2 AIV poses a major threat to the chicken industry worldwide. Here, we developed a recombinant fowlpox virus (rFPV-HA) expressing the haemagglutinin (HA) gene of the A/CH/JY/1/05 (H9N2) influenza virus and a recombinant fowlpox virus (rFPV-HA/IL18) expressing the HA gene and chicken interleukin-18 (IL-18) gene. Recombinant plasmid pSY-HA/IL18 was constructed by cloning chicken IL-18 expression cassette into recombinant plasmid pSY-HA containing the HA gene. Two rFPVs were generated by transfecting two recombinant plasmids into the chicken embryo fibroblast cells pre-infected with S-FPV-017, and assessed for their immunological efficacy on one-day-old White Leghorn specific-pathogen-free chickens challenged with the A/CH/JY/1/05 (H9N2) strain. There was a significant difference in HI antibody levels ( P < 0.05) elicited by either rFPV-HA or rFPV-HA/IL18. The level of splenocyte proliferation response in the rFPV-HA/IL18-vaccinated group was significantly higher ( P < 0.05) than that in the rFPV-HA group. After challenge with 10 6.5 ELD 50 H9N2 AIV 43 days after immunization, rFPVs vaccinated groups could prevent virus shedding and replication in multiple organs in response to H9N2 AIV infection, and rFPV-HA/IL18 vaccinated group had better inhibition of viruses than rFPV-HA vaccinated group. Our results show that the protective efficacy of the rFPV-HA vaccine could be enhanced significantly by simultaneous expression of IL-18.

Immune Responses of Mice Intraduodenally Infected withToxoplasma gondiiKI-1 Tachyzoites

Toxoplasma gondii Korean isolate (KI-1) tachyzoites were inoculated intraduodenally to BALB/c mice using a silicon tube, and the course of infection and immune responses of mice were studied. Whereas control mice, that were infected intraperitoneally, died within day 7 post-infection (PI), the intraduodenally infected mice survived until day 9 PI (infection with 1×105 tachyzoites) or day 11 PI (with 1×106 tachyzoites). Based on histopathologic (Giemsa stain) and PCR (B1 gene) studies, it was suggested that tachyzoites, after entering the small intestine, invaded into endothelial cells, divided there, and propagated to other organs. PCR appeared to be more sensitive than histopathology to detect infected organs and tissues. The organisms spread over multiple organs by day 6 PI. However, proliferative responses of splenocytes and mesenteric lymph node (MLN) cells in response to con A or Toxoplasma lysate antigen decreased significantly, suggesting immunosuppression. Splenic CD4+ and CD8+ T-lymphocytes showed decreases in number until day 9 PI, whereas IFN-γ and IL-10 decreased slightly at day 6 PI and returned to normal levels by day 9 PI. No TNF-α was detected throughout the experimental period. The results showed that intraduodenal infection with KI-1 tachyzoites was successful but did not elicit significant mucosal immunity in mice and allowed dissemination of T. gondii organisms to systemic organs. The immunosuppression of mice included reduced lymphoproliferative responses to splenocytes and MLN cells to mitogen and low production of cytokines, such as IFN-γ, TNF-α, and IL-10, in response to T. gondii infection.

Immunization with DNA Vaccine Expressing Herpes Simplex Virus Type 1 gD and IL-21 Protects against Mouse Herpes Keratitis

The development of novel vaccines to eradicate herpes simplex virus (HSV) is a global public health priority. In this study, we developed a DNA vaccine expressing HSV-1 glycoprotein D (gD) and mouse interleukin-21(IL-21) and intramuscularly inoculated mice 3 times at 2-week intervals with a total of 300 μg/mouse. Two weeks after the last immunization the specific antibody, splenocyte proliferative response to gD, IFN-γ and IL-4 as well as the cytotoxic activities of splenocytes and natural killer (NK) cells were assayed. Immune protection against herpes keratitis was concurrently evaluated in the immunized mice after HSV-1 challenge of the mouse cornea. The results showed that the DNA vaccine pRSC-gD-IL-21 generated higher levels of antibody, IFN-γ and IL-4, and enhanced the splenocyte proliferative response to gD as well as the cytotoxic activity of splenocytes and NK cells to target cells compared with the response in either the pRSC-gD or mock plasmid pRSC immunized mice. Importantly, the pRSC-gD-IL-21 ameliorated herpes keratitis severity and time course after corneal infection with HSV-1. The findings suggest that the DNA vaccine pRSC-gD-IL-21 may induce an immune response that can limit HSV-1 infection and development of herpes keratitis in the immunized mice.

Antitumor efficacy induced by a B16F10 tumor cell vaccine treated with mitoxantrone alone or in combination with reserpine and verapamil in mice

An apoptotic tumor cell serves as a potential potent trigger for the initiation of naturally occurring tumor immunity. In the present study, a B16F10 tumor cell vaccine treated with mitoxantrone (MIT) was developed, and its antitumor effect on mice was evaluated. The results indicated that the B16F10 tumor cell vaccine treated with MIT alone or in combination with reserpine (RP) and verapamil (VP) for 12 h triggered apoptosis, and that the expression of CD80, the MHC II class molecule, NKG2D and its ligand were significantly increased compared to the expression levels in the control group. The tumor vaccine immunogenicity was significantly enhanced in the vaccinated mice, resulting in augmented cytotoxicity of splenocytes and NK cells as well as the splenocyte proliferative response compared to the control group mice. Notably, the mice vaccinated with the B16F10 tumor cell vaccine treated with MIT, RP and VP did not generate tumors only after 60 days into the observation, but the mice also generated a powerful immune prophylactic efficiency against the B16F10 tumor cell challenge. These findings demonstrated the safety and efficacy of the B16F10 tumor cell vaccine treated with MIT alone or in combination with RP and VP in the murine model, and suggest that an apoptotic tumor cell vaccine modeled on naturally occurring tumor immune responses in vivo may provide a safe and immunogenic tumor vaccine for potential applications in humans.

An ocular mucosal administration of nanoparticles containing DNA vaccine pRSC-gD-IL-21 confers protection against mucosal challenge with herpes simplex virus type 1 in mice

Herpes stromal keratitis (HSK) is a chronic inflammatory process caused by the infection of herpes simplex virus type 1 (HSV-1). Development of a HSV-1 vaccine is a priority because these infections are common and cannot be well prevented. It appears that the potential of nanocarriers in DNA vaccination will be required to augment the immune response to DNA vaccines. Therefore, in the study, nanoparticles Fe3O4 coated with glutamic acid, DNA vaccine pRSC-gD-IL-21 and polyethylenimine were prepared and immunized in the mice by ocular mucosal administration. The immune responses and protection efficiency against HSV-1 challenge were also tested. The results showed that the nanoparticles containing DNA vaccine pRSC-gD-IL-21 induced mice to generate higher levels of specific neutralizing antibody, sIgA in tears, and IFN-γ, IL-4 in serum, and to enhance the cytotoxicities of NK cells and splenocytes as well as splenocyte proliferative response to glycoprotein D compared with those of the control mice. More importantly, the mice immunized with the experimental vaccine showed less HSK degree than that of the control mice after HSV-1 challenge of the murine ocular mucosa. In conclusion, an ocular mucosal administration of nanoparticles containing DNA vaccine confers strong specific immune responses and effective inhibition of HSK in a HSV-1 infected murine model.

Interleukin-18-mediated enhancement of the protective effect of an infectious laryngotracheitis virus glycoprotein B plasmid DNA vaccine in chickens

The immunogenicity of an infectious laryngotracheitis virus (ILTV) glycoprotein B (gB) plasmid DNA vaccine and the immunoregulatory activity of chicken interleukin-18 (IL-18) were investigated in a challenge model. Two recombinant plasmids, pcDNA3.1/gB (pgB) and pcDNA3.1/IL-18 (pIL-18), containing gB and IL-18 were constructed. Chickens were intramuscularly administered two immunizations 2&emsp14;weeks apart, and challenged with the virulent CG strain of ILTV 2&emsp14;weeks later. All animals vaccinated with pgB alone or with a combination of pgB plus pIL-18 developed a specific anti-ILTV ELISA antibody and splenocyte proliferation response. The ratios of CD4(+) to CD8(+) T lymphocytes in chickens immunized with pgB plus pIL-18 were significantly higher than in those immunized with pgB alone. Co-injection of pIL-18 significantly increased the production of gamma interferon and IL-2, indicating that IL-18 enhances the T helper 1-dominant immune response. Challenge experiments showed that the morbidity rate in the pgB group (25 %) was significantly higher than that in the pgB plus pIL-18 group (10 %). The mortality rates in the pgB and pgB plus pIL-18 groups were 10 and 0 %, respectively, and the corresponding protection rates were 60 and 80 %. These results indicate that IL-18 may be an effective adjuvant for an ILTV vaccine.

Total body glutathione depletion induces oxidative stress and disrupts the immune function in mice

The effect of total body glutathione (GSH) depletion induced by L-buthionine-(S,R)-sulfoximine (BSO) treatment on the murine immune system has not been studied previously. BSO was administered via drinking water for 14 days to induce total body GSH depletion. A significant decrease in total GSH (TGSH) of the immune organs such as spleen, liver, peritoneal macrophages as well as blood was observed. The proliferative response of splenocytes against different types of mitogens was significantly decreased in GSH-depleted mice compared to controls. The expression of several antioxidant enzymes was studied in both treated and control mice. No significant change was seen in major antioxidant enzymes; manganese superoxide dismutase and catalase. However, the expression of heme oxygenase-1 was increased in both liver and spleen in BSO-treated mice. Total body GSH depletion also increased lipid peroxidation as demonstrated by higher levels of malondialdehyde in BSO-treated mice. All the above-mentioned changes were reversed to near normal 14 days post termination of BSO treatment. These results demonstrate that TGSH depletion induces oxidative stress and adversely affects the function of the murine immune system.

Development and immunogenicity of a recombinant pseudorabies virus expressing Sj26GST and SjFABP from Schistosoma japonicum

Recombinant pseudorabies virus (PRV) Bartha-K61 vaccine strains expressing Schistosoma japonicum 26kDa glutathione S-transferase (Sj26GST) and fatty acid binding protein (SjFABP), designated as rPRV/Sj26GST, rPRV/SjFABP and rPRV/Sj26GST-SjFABP, were constructed and evaluated for their ability to protect mice and sheep against S. japonicum challenge. Animals were given 2 intramuscular immunizations 3 weeks apart, and challenged with S. japonicum cercariae 4 weeks later. All mice vaccinated with recombinant virus developed specific anti-SWAP (soluble worm antigen preparation) antibody, splenocyte proliferative response and production of IFN-γ and IL-2. Injection of rPRV/Sj26GST-SjFABP significantly increased levels of antibody, splenocyte proliferative response and production of IFN-γ, compared with rPRV/Sj26GST and rPRV/SjFABP. These recombinant viruses have been shown to be safe for sheep. Challenge experiments showed worms and egg burdens were significantly reduced in animals immunized with recombinant PRVs. Most importantly, rPRV/Sj26GST-SjFABP dramatically enhanced protection with worm reduction and hepatic reduction of 39.3% and 45.5% respectively in mice, and 48.5% and 51.2% in sheep, while rPRV/Sj26GST and rPRV/SjFABP provided corresponding protection of only up to 23.7% and 27.2% in mice, and 29.0% and 35.5% in sheep. These results indicate that the multivalent vaccine for S. japonicum can produce significant specific immunity and protection, and that PRV Bartha-K61 is an effective live vector for an animal schistosomiasis japonica vaccine.

Pregnancy induces a fetal antigen-specific maternal T regulatory cell response that contributes to tolerance

A fetus is inherently antigenic to its mother and yet is not rejected. The T regulatory (Treg) subset of CD4(+) T cells can limit immune responses and has been implicated in maternal tolerance of the fetus. Using virgin inbred mice undergoing a first syngenic pregnancy, in which only the male fetuses are antigenic, we demonstrate a maternal splenocyte proliferative response to the CD4(+) T cell restricted epitope of the male antigen (H-Y) in proportion to the fetal antigen load. A portion of the maternal immune response to fetal antigens is Treg in nature. The bystander suppressive function of pregnancy-generated Tregs requires the presence of the fetal antigen, demonstrating their inherent antigen specificity. In vivo targeting of diphtheria toxin to kill Tregs leads to a lower fraction of live male offspring and a selective reduction in mass of the surviving males. Thus, Tregs generated in the context of pregnancy function in an antigen-specific manner to limit the maternal immune response to the fetus in a successful pregnancy.

Estradiol and G1 Reduce Infarct Size and Improve Immunosuppression after Experimental Stroke

Reduced risk and severity of stroke in adult females is thought to depend on normal endogenous levels of estrogen, a well-known neuroprotectant and immunomodulator. In male mice, experimental stroke induces immunosuppression of the peripheral immune system, characterized by a reduction in spleen size and cell numbers and decreased cytokine and chemokine expression. However, stroke-induced immunosuppression has not been evaluated in female mice. To test the hypothesis that estradiol (E2) deficiency exacerbates immunosuppression after focal stroke in females, we evaluated the effect of middle cerebral artery occlusion on infarct size and peripheral and CNS immune responses in ovariectomized mice with or without sustained, controlled levels of 17-beta-E2 administered by s.c. implant or the putative membrane estrogen receptor agonist, G1. Both E2- and G1-replacement decreased infarct volume and partially restored splenocyte numbers. Moreover, E2-replacement increased splenocyte proliferation in response to stimulation with anti-CD3/CD28 Abs and normalized aberrant mRNA expression for cytokines, chemokines, and chemokine receptors and percentage of CD4(+)CD25(+)FoxP3(+) T regulatory cells observed in E2-deficient animals. These beneficial changes in peripheral immunity after E2 replacement were accompanied by a profound reduction in expression of the chemokine, MIP-2, and a 40-fold increased expression of CCR7 in the lesioned brain hemisphere. These results demonstrate for the first time that E2 replacement in ovariectomized female mice improves stroke-induced peripheral immunosuppression.

Combined ascorbate and glutathione deficiency leads to decreased cytochrome b 5 expression and impaired reduction of sulfamethoxazole hydroxylamine

Sulfonamide antimicrobials such as sulfamethoxazole (SMX) have been associated with drug hypersensitivity reactions, particularly in patients with AIDS. A reactive oxidative metabolite, sulfamethoxazole-nitroso (SMX-NO), forms drug-tissue adducts that elicit a T-cell response. Antioxidants such as ascorbic acid (AA) and glutathione (GSH) reduce SMX-NO to the less reactive hydroxylamine metabolite (SMX-HA), which is further reduced to the non-immunogenic parent compound by cytochrome b (5) (b5) and its reductase (b5R). We hypothesized that deficiencies in AA and GSH would enhance drug-tissue adduct formation and immunogenicity toward SMX-NO and that these antioxidant deficiencies might also impair the activity of the b5/b5R pathway. We tested these hypotheses in guinea pigs fed either a normal or AA-restricted diet, followed by buthionine sulfoximine treatment (250 mg/kg SC daily, or vehicle); and SMX-NO (1 mg/kg IP 4 days per week, or vehicle), for 2 weeks. Guinea pigs did not show any biochemical or histopathologic evidence of SMX-NO-related toxicity. Combined AA and GSH deficiency in this model did not significantly increase tissue-drug adduct formation, or splenocyte proliferation in response to SMX-NO. However, combined antioxidant deficiency was associated with decreased mRNA and protein expression of cytochrome b (5), as well as significant decreases in SMX-HA reduction in SMX-NO-treated pigs. These results suggest that SMX-HA detoxification may be down-regulated in combined AA and GSH deficiency. This mechanism could contribute to the higher risk of SMX hypersensitivity in patients with AIDS with antioxidant depletion.

FcγRIIB Inhibits the Development of Atherosclerosis in Low-Density Lipoprotein Receptor-Deficient Mice

The immune processes associated with atherogenesis have received considerable attention during recent years. IgG FcRs (FcgammaR) are involved in activating the immune system and in maintaining peripheral tolerance. However, the role of the inhibitory IgG receptor FcgammaRIIB in atherosclerosis has not been defined. Bone marrow cells from FcgammaRIIB-deficient mice and C57BL/6 control mice were transplanted to low-density lipoprotein receptor-deficient mice. Atherosclerosis was induced by feeding the recipient mice a high-fat diet for 8 wk and evaluated using Oil Red O staining of the descending aorta at sacrifice. The molecular mechanisms triggering atherosclerosis was studied by examining splenic B and T cells, as well as Th1 and Th2 immune responses using flow cytometry and ELISA. The atherosclerotic lesion area in the descending aorta was ~5-fold larger in mice lacking FcgammaRIIB than in control mice (2.75 +/- 2.57 versus 0.44 +/- 0.42%; p < 0.01). Moreover, the FcgammaRIIB deficiency resulted in an amplified splenocyte proliferative response to Con A stimulation (proliferation index 30.26 +/- 8.81 versus 2.96 +/- 0.81%, p < 0.0001) and an enhanced expression of MHC class II on the B cells (6.65 +/- 0.64 versus 2.33 +/- 0.25%; p < 0.001). In accordance, an enlarged amount of CD25-positive CD4 T cells was found in the spleen (42.74 +/- 4.05 versus 2.45 +/- 0.31%; p < 0.0001). The plasma Ab and cytokine pattern suggested increased Th1 and Th2 immune responses, respectively. These results show that FcgammaRIIB inhibits the development of atherosclerosis in mice. In addition, they indicate that absence of the inhibiting IgG receptor cause disease, depending on an imbalance of activating and inhibiting immune cells.

Intranasal administration of plasmid DNA-coated nanoparticles results in enhanced immune responses.

Intranasal immunization offers potential forthe elicitation of effective mucosal and systemic immune responses. In this study, a previously reported novel cationic nanoparticle engineered from a microemulsion precursor was further modified, optimized and applied intranasally to mice to explore its potential as a plasmid DNA (pDNA) vaccine delivery system. To this end, more uniform nanoparticles (around 100 nm) containing less cationic surfactant were developed. The pDNA-coated nanoparticles significantly enhanced the specific serum IgG and IgA titres to an expressed model antigen, beta-galactosidase, by 18-28 and 25-30 fold, respectively, when compared with naked pDNA alone. An enhanced splenocyte proliferative response was also observed after immunization with the pDNA-coated nanoparticles. It was concluded that these plasmid DNA-coated nanoparticles may have potential for immunization via the nasal route.

In vivo but not in vitro leptin enhances lymphocyte proliferation in Siberian hamsters ( Phodopus sungorus)

Mounting an immune response requires a relatively substantial investment of energy and marked reductions in energy availability can suppress immune function and presumably increase disease susceptibility. We have previously demonstrated that a moderate reduction in energy stores by partial surgical lipectomy impairs humoral immunity of Siberian hamsters ( Phodopus sungorus) and is mediated, in part, by changes in the adipose tissue hormone leptin. The goals of the present study were to assess the role of leptin in cell-mediated immunity and to determine if the potential effects of leptin on immunity are via the direct actions of this hormone on lymphocytes, or indirect, via the sympathetic nervous system (SNS). In Experiment 1, hamsters received osmotic minipumps containing either murine leptin (0.5 μl/h) or vehicle alone for 10 days and splenocyte proliferation in response to the T-cell mitogen Concanavalin A (Con A) was determined. In Experiment 2, Con A-induced splenocyte proliferation was tested in the presence or absence of leptin in vitro. In Experiment 3, exogenous leptin was administered to intact or sympathetically denervated hamsters. Hamsters treated with in vivo leptin displayed increased splenocyte proliferation compared with control hamsters receiving vehicle. In contrast, in vitro leptin had no effect on splenocyte proliferation. Sympathetic denervation attenuated, but did not block, leptin-induced increases in immunity. Taken together, these results are consistent with the idea that leptin can enhance cell-mediated immunity; the SNS appears to contribute, least in part, to leptin-induced increases in immunity. Importantly, these findings confirm previous studies that leptin serves as an important endocrine link between energy balance and immunity.

Opposite effects of nanocrystalline fullerene (C 60) on tumour cell growth in vitro and in vivo and a possible role of immunosupression in the cancer-promoting activity of C 60

In the present study, we compared the effects of nanocrystalline fullerene suspension (nanoC 60) on tumour cell growth in vitro and in vivo. NanoC 60 suspension was prepared by solvent exchange using tetrahydrofuran to dissolve C 60. In vitro, nanoC 60 caused oxidative stress, mitochondrial depolarization and caspase activation, leading to apoptotic and necrotic death in mouse B16 melanoma cells. Biodistribution studies demonstrated that intraperitoneally injected radiolabeled ( 125I) nanoC 60 readily accumulated in the tumour tissue of mice subcutaneously inoculated with B16 cells. However, intraperitoneal administration of nanoC 60 over the course of two weeks starting from melanoma cell implantation not only failed to reduce, but significantly augmented tumour growth. The tumour-promoting effect of nanoC 60 was accompanied by a significant increase in splenocyte production of the immunoregulatory free radical nitric oxide (NO), as well as by a reduction in splenocyte proliferative responses to T- and B-cell mitogens ConcanavalinA and bacterial lipopolysaccharide, respectively. A negative correlation between NO production and splenocyte proliferation indicated a possible role of NO in reducing the proliferation of splenocytes from nanoC 60-injected mice. These data demonstrate that nanoC 60, in contrast to its potent anticancer activity in vitro, can potentiate tumour growth in vivo, possibly by causing NO-dependent suppression of anticancer immune response.

Optimization of medium composition for the production of exopolysaccharides from Phellinus baumii Pilát in submerged culture and the immuno-stimulating activity of exopolysaccharides

Abstract Optimization of medium composition for the production of exopolysaccharides (EPS) from Phellinus baumii Pilat in submerged culture and the immuno-stimulating activity of EPS were carried out. Firstly, the medium components having significant effect on EPS production were screened out to be glucose, yeast extract and diammonium oxalate monohydrate by using a 2 (7−3) fractional factorial design. Secondly, the concentrations of the three factors were optimized using central composite design in response surface methodology. As results, a quadratic model was found to fit for EPS production, and the optimal medium composition was determined as following (g/l): 34.12 glucose, 4 peptone, 5.01 yeast extract, 0.88 diammonium oxalate monohydrate, 0.75 MgSO 4 and 1 KH 2 PO 4 and 0.0075 thiamine (VB 1 ). A yield of 2.363 ± 0.04 g/l for EPS was observed in verification experiment. Finally, EPS from P. baumii Pilat was found to have direct immuno-stimulating activity in vitro on splenocyte proliferative response and acid phosphatase activity in peritoneal macrophages in a dose-dependent manner.

Higher immunoglobulin production in conjugated linoleic acid-supplemented rats during gestation and suckling

Conjugated linoleic acid (CLA) has been reported to exert beneficial physiological effects on body composition and the immune system. However, little information is available on the influence of CLA on immune function during early life periods. The present study evaluates the effect of feeding an 80:20 mixture of cis-9, trans-11- and trans-10, cis-12-CLA isomers during gestation and suckling on the systemic immune response of weaned Wistar rats. Pups received dietary CLA from dams through the placental barrier and during suckling by breast milk (group A) or by oral administration (group B). Pups from group C only received CLA during suckling by oral administration. Group D constituted the reference group. Milk from dams fed the CLA diet had a high content of CLA and higher IgA and IgG concentrations than rats fed the standard diet. The plasma of pups from groups A, B and C showed six, twelve and nine times higher content of the cis-9, trans-11-CLA isomer than that of the group D pups. Rats from group A exhibited higher serum IgG concentrations than rats from the rest of the groups (22.14 (SEM 2.14) v. about 5 mg/ml; P < 0.05), whereas rats from groups A and B showed approximately 2-fold higher splenocyte IgM production than rats from groups C and D. However, CLA supplementation did not influence significantly the splenocyte proliferative response or cytokine secretion. Supplementation during gestation and suckling with an 80:20 cis-9, trans-11-trans-10, cis-12 CLA mix enhances the production of the main in vivo and in vitro Ig isotypes in Wistar rats.

Protection in mice immunized with a heterologous prime-boost regime using DNA and recombinant pseudorabies expressing TgSAG1 against Toxoplasma gondii challenge

An effective vaccine of animals can block transmission of Toxoplasma gondii to humans. In this study, mice have been protected against lethal T. gondii challenge by a prime-boost vaccination strategy using DNA vaccine pVAX/TgSAG1 and recombinant pseudorabies virus rPRV/TgSAG1, both expressing the major immunodominant surface antigen of T. gondii (TgSAG1). High levels of splenocyte proliferative responses and significant levels of IFN-γ resulted, with strong cytotoxic T lymphocyte (CTL) responses in vitro. After lethal challenge, prime-boost vaccinated mice showed an increased survival time (15.4 ± 5.0 days) and a 40% survival rate compared with controls who all died within 11 days of challenge. Results of the present study indicated that this novel immunization strategy is useful in enhancing immune protection in mice against lethal T. gondii infection, which would provide foundation for the development of effective vaccines against T. gondii.

Evidence for the Nucleus Accumbens as a Neural Substrate of Heroin-Induced Immune Alterations

Administration of opioid drugs such as heroin produces several immunosuppressive effects, including decreases in natural killer (NK) cell activity, lymphocyte proliferative responses, and nitric oxide production. Interestingly, opioids have been shown to alter many immune parameters indirectly by modulating the immunoregulatory actions of the central nervous system. Recently, it has been demonstrated that morphine inhibits NK cell activity through a neural pathway that requires the activation of dopamine D(1) receptors in the nucleus accumbens shell. The present study examined whether the nucleus accumbens also mediates the effects of heroin, a more commonly abused opioid, on several parameters of immune status in Lewis rats. The results showed that bilateral administration of the dopamine D(1) receptor antagonist R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH-23390; 0.015 and 0.15 microg/side) into the nucleus accumbens shell blocked decreases in splenic NK activity produced by heroin (3 mg/kg s.c.) but did not attenuate the suppression of splenocyte proliferative responses to concanavalin-A or lipopolysaccharide (LPS). A subsequent experiment was performed to evaluate the effect of D(1) receptor antagonism on LPS-induced expression of inducible nitric-oxide synthase (iNOS) in vivo. These results showed that intra-accumbens SCH-23390 administration prevented heroin-induced reductions of iNOS mRNA expression in spleen, liver, and lung tissues and attenuated the suppression of nitric oxide levels in plasma. Collectively, these findings indicate that nucleus accumbens dopamine D(1) receptors are critically involved in heroin-induced immune alterations.

CpG-ODN combined with Neospora caninum lysate, but not with excreted-secreted antigen, enhances protection against infection in mice

CpG oligodeoxynucleotides (ODN) have shown to be potent immunoadjuvants for several pathogens, but there is limited information concerning their use in immunization protocols against neosporosis. This study aimed to evaluate the potential of CpG-ODN combined with Neospora lysate antigen (NLA) or excreted-secreted antigen (NcESA) to induce protective immune response against Neospora caninum infection in mice. C57BL/6 mice were vaccinated subcutaneously three times at 2-week intervals with NLA, NLA + CpG, NcESA, NcESA + CpG, CpG (adjuvant control) or PBS (infection control). Serological assays showed an increased specific IgG2a response in animals immunized with either antigen plus adjuvant and elevated levels of the IgG1 isotype in those vaccinated with antigens alone. Splenocyte proliferative responses upon antigen stimulation were higher in groups immunized with NLA or NcESA combined with CpG, showing increased IL-12 levels. Also, mice vaccinated with NcESA or NcESA + CpG demonstrated higher IFN-γ levels and IFN-γ/IL-10 ratio. After lethal challenge, mice immunized with NLA + CpG or NLA had lower morbidity score and body weight changes in comparison to other groups, and animals did not succumb during acute infection. In contrast, NcESA + CpG or NcESA groups exhibited the highest morbidity scores, body weight impairment and mortality rates, associated with greatest brain parasite burden and inflammation. In conclusion, CpG-ODN was able to induce a Th1-type humoral immune response with predominant IgG2a levels for either NLA or NcESA, but resulting in an effective Th1-driven cellular immune response and total protection only when combined with NLA. Vaccination with NcESA alone or combined with CpG resulted in a strong cellular immune response associated with high levels of IFN-γ and inflammation, rendering mice more susceptible to parasite challenge.