Immune Response Of Splenocytes Research Articles

Adaptive immune response in Alzheimer’s disease: untangling the role of ApoE4

AbstractBackgroundThe strongest genetic risk factor for developing late‐onset Alzheimer’s disease (AD), ApoE4, drives inflammation in the central immune system. However, it remains largely unkown whether ApoE4 also affects the adaptive immune response.MethodFirst, we performed mass cytometry to identify an immune signature in splenocytes of human ApoE4‐TR and ApoE3‐TR mice. Following this, we used immunohistochemistry to check for brain infiltration of immune cells and BBB integrity.ResultWe identified an adaptive immune response in splenocytes of human ApoE4‐TR mice displayed by a shift from naïve and effector to memory CD8+ T cells. Futhermore, we found an increased number of CD8+ T cells in the brain of ApoE4‐TR mice. ApoE4 also has an effect on BBB integrity, as indicated by a decrease in the tight junction proteins, VE‐cadherin and claudin‐5, in ApoE4‐TR mice compared to ApoE3‐TR mice.ConclusionApoE4 induces an adaptive immune response in mouse splenocytes resulting in brain infiltration of CD8+ T cells.

Molecular and immunological characterization of the calcyclin binding protein in rodent malaria parasite

Malaria remains as a global life-threatening disorder due to the emergence of resistance against standard antimalarials. Consequently, there is a serious need to better understand the biology of the malaria parasite in order to determine appropriate targets for new interventions. Calcyclin binding protein (CacyBP) is a multi-functional and multi-ligand protein that is not well characterized in malaria disease. In this study, we have cloned CacyBP from rodent species Plasmodium yoelii nigeriensis and purified the recombinant protein to carry out its detailed molecular, biophysical and immunological characterization. Molecular characterization indicates that PyCacyBP is a ∼27 kDa protein in parasite lysate and exists in monomer and dimer forms. Bioinformatic analysis of CacyBP showed significant sequence and structural similarities between rodent and human malaria parasites. CacyBP is expressed in all blood stages of P. yoelii nigeriensis parasite. In silico studies proposed the immunogenic potential of CacyBP. The rPyCacyBP immunized mice exhibited elevated levels of IgG1, IgG2a, IgG2b and IgG3 in their serum. Notably, cellular immune response in splenocytes from immunized mice showed increased expression of pro-inflammatory cytokines such as IL-12, IFN-γ and TNF-α. This CacyBP exhibited pro-inflammatory immune response in rodent host. These finding revealed that CacyBP may have the potential to boost the host immunity for protection against malaria infection. The present study provides basis for further exploration of the biological function of CacyBP in malaria parasite.

Circadian rhythm disruption exacerbates Th2-like immune response in murine allergic airway inflammation.

BackgroundChronic jet lag (CJL)‐induced circadian rhythm disruption (CRD) is positively correlated with an increased risk of allergic diseases. However, little is known about the mechanism involved in allergic rhinitis (AR).MethodsAberrant light/dark cycles‐induced CRD mice were randomly divided into negative control (NC) group, AR group, CRD+NC group, and CRD+AR group (n = 8/group). After ovalbumin (OVA) challenge, nasal symptom scores were recorded. The expression of Occludin and ZO‐1 in both nasal mucosa and lung tissues was detected by reverse transcription–quantitative polymerase chain reaction (RT‐PCR) and immunohistochemical staining. The level of OVA–specific immunoglobulin E (sIgE) and T‐helper (Th)‐related cytokines in the plasma was measured by enzyme‐linked immunosorbent assay (ELISA), and the proportion of Th1, Th2, Th17, and regulatory T cell (Treg) in splenocytes was evaluated by flow cytometry.ResultsThe nasal symptom score in the CRD+AR group was significantly higher than those in the AR group with respect to eosinophil infiltration, mast cell degranulation, and goblet cell hyperplasia. The expression of ZO‐1 and Occludin in the nasal mucosa and lung tissues in the CRD+AR group were significantly lower than those in the AR group. Furthermore, Th2 and Th17 cell counts from splenocytes and OVA‐sIgE, interleukin 4 (IL‐4), IL‐6, IL‐13, and IL‐17A levels in plasma were significantly increased in the CRD+AR group than in the AR group, whereas Th1 and Treg cell count and interferon γ (IFN‐γ) level were significantly decreased in the CRD+AR group.ConclusionCRD experimentally mimicked CJL in human activities, could exacerbate local and systemic allergic reactions in AR mice, partially through decreasing Occludin and ZO‐1 level in the respiratory mucosa and increasing Th2‐like immune response in splenocytes.

Correction of immunosuppression in aged septic rats by human ghrelin and growth hormone through the vagus nerve-dependent inhibition of TGF-\u03b2 production

BackgroundCo-administration of human ghrelin and growth hormone (GH) reverse immunosuppression in septic aged animals, but the mechanism remains elusive. Here, we hypothesize that ghrelin and GH co-treatment restores the immune response in aged septic rats by inhibiting the production of transforming growth factor-β (TGF-β), an immunoregulatory cytokine, through the vagus nerve.MethodsMale aged Fischer rats (22–23-month-old) were made septic by cecal ligation and puncture (CLP) with or without dissecting the vagus nerve (vagotomy). Human ghrelin and GH or vehicle (PBS) were administrated subcutaneously at 5 h post CLP. After 20 h of CLP, serum and spleens were harvested.ResultsSerum TGF-β levels were increased in septic aged rats, while ghrelin and GH treatment significantly reduced its levels. Expression of TGF-β in the spleen was upregulated after sepsis, while ghrelin and GH treatment significantly inhibited its expression. TNF-α and IL-6 levels were significantly reduced after ex vivo LPS stimulation of splenocytes from rats that underwent CLP compared to sham rats; while these levels were significantly higher in splenocytes from ghrelin and GH-treated CLP rats compared to vehicle-treated CLP rats. Ghrelin and GH treatment reduced program death receptor-1 (PD-1) expression, increased human leukocyte antigen-DR (HLA-DR) expression, attenuated lymphopenia, and cleaved caspase-3 levels in the spleen of septic aged rats. Vagotomy diminished the beneficial effects of ghrelin and GH treatment in septic rats. In vitro, the addition of ghrelin, GH, or ghrelin and GH together had no effect on restoring immune response in splenocytes from CLP rats following LPS stimulation, indicating the requirement of the vagus nerve for ghrelin and GH’s effect.ConclusionsGhrelin and GH attenuate immunosuppression in aged septic rats through the vagus nerve-dependent inhibition of TGF-β production.

Effects of exercise training and supplementation with selenium nanoparticle on T-helper 1 and 2 and cytokine levels in tumor tissue of mice bearing the 4 T1 mammary carcinoma.

Physical exercise decreases the incidence of breast cancer and also improves survival in breast cancer patients. However, the mechanistic basis of these protective effects of exercise is not well known. Changes in tumor cytokines, such as oncostatin-M (OSM), have been associated with modulation of antitumor immune responses in breast cancer. Exercise and antioxidants such as selenium affect both antitumor immune responses as well as tumor cytokine expression. Thus, the aim of this study was to determine the effects of aerobic exercise training (AET) and selenium nanoparticle (SeNP) administration on T-helper 1 and 2 and tumor tissue cytokines in mice bearing the 4 T1 mammary carcinoma. We examined the effects of 6 wk of AET and SeNP administration (100 μg three times/wk) on tumor size, concentration of tumor necrosis factor (TNF)-α, interleukin (IL)-6, interferon (IFN)-γ, IL-4 and OSM in tumor tissue and INF-γ and IL-4 in splenocytes of 64 mice bearing the 4 T1 mammary carcinoma. AET increased OSM levels in tumor tissue. Moreover, AET increased levels of TNF-α in tumor tissue, whereas SeNP supplementation decreased IL-4 levels tumor tissue. Also, the combination of AET and SeNP administration decreased tumor volume and increased T-helper 1 cytokines in the splenocytes of tumor-bearing mice. These findings suggest that the combination of AET and SeNP supplementation effects antitumor immune responses in splenocytes, whereas AET induced antitumor cytokines, such as OSM and TNF-α in tumor tissue.

MUC1- and Survivin-based DNA Vaccine Combining Immunoadjuvants CpG and interleukin-2 in a Bicistronic Expression Plasmid Generates Specific Immune Responses and Antitumour Effects in a Murine Colorectal Carcinoma Model.

DNA vaccination is a promising cancer treatment due to its safety, but poor immunogenicity limits its application. However, immunoadjuvants, heterogeneous prime-boost strategies and combination with conventional treatments can be used to improve the antitumour immune effects. A CpG motif and interleukin-2 (IL-2) cytokine are often used as adjuvants. In this study, a DNA vaccine containing a CpG motif was constructed to evaluate its adjuvant effect. The results show that the cytotoxicity of the DNA vaccine was increased fivefold, and survival lifetime was prolonged twofold by the CpG motif adjuvant. To simplify the industrial production process, a bicistronic plasmid was constructed to carry the fusion genes of survivin/MUC1 (MS) and IL-2 and with a CpG motif in its backbone. The results showed that the antitumour effect of the bicistronic vaccine was the same as that of the two vaccine co-injected regime. Furthermore, the vaccine could suppress metastatic tumour foci by 69.1% in colorectal carcinoma-bearing mice. Moreover, the vaccine induced survivin- and MUC1-specific immune responses in splenocytes and induced the immune promoting factor CCL-19 and GM-CSF upregulated, while metastatic-associated factor MMP-9 and immunosuppressing factor PD-L1 downregulated in tumour tissue. When combining the vaccine with the chemotherapy drug oxaliplatin, the survival was prolonged by about 2.5-fold. In conclusion, the DNA vaccine containing a CpG motif in bicistronic form showed good effects on colorectal cancer by inhibiting both tumour growth and metastasis, and combination with oxaliplatin could improve its antitumour effects.

Stimulation of murine cell-mediated immunity by dietary administration of a cell preparation of Enterococcus faecalis strain KH-2 and its possible activity against tumour development in mice.

It is well known that dietary lactic acid bacteria (LAB) stimulate cell-mediated immunity such as natural killer (NK) activity in mice. Here, we aimed to assay the immunomodulatory effects of a cell preparation of Enterococcus faecalis strain KH-2 (CPEF). We further evaluated the possibility of antitumour activity caused by CPEF administration, because NK cells actively participate in the prevention of tumour formation. NK cell activity and gene expression of IFN-γ and Perforin 1, which were induced most likely by a synergetic action of their cytotoxic activity, were higher in splenocytes of CPEF-administered mice than they were in control mice. Moreover, unlike those of control mice, the splenocytes of CPEF-administered mice had significantly higher CD28+CD69+/CD4+ and CD28+CD69+/CD8+ ratios that resulted in a survival rate with a tendency toward improvement after 47 days of CPEF administration (p=0.1) in Meth-A fibrosarcoma-bearing mice. In conclusion, we showed that CPEF might be effective in treating Meth-A fibrosarcoma in mice, as it helped increase their survival rate via stimulation of an immune response in splenocytes, which involved systemic cellular immunity processes such as cytotoxic activity, and active T cells.

Immunization with Tc52 or its amino terminal domain adjuvanted with c-di-AMP induces Th17+Th1 specific immune responses and confers protection against Trypanosoma cruzi.

The development of new adjuvants enables fine modulation of the elicited immune responses. Ideally, the use of one or more adjuvants should result in the induction of a protective immune response against the specific pathogen. We have evaluated the immune response and protection against Trypanosoma cruzi infection in mice vaccinated with recombinant Tc52 or its N- and C-terminal domains (NTc52 and CTc52) adjuvanted either with the STING (Stimulator of Interferon Genes) agonist cyclic di-AMP (c-di-AMP), a pegylated derivative of α-galactosylceramide (αGC-PEG), or oligodeoxynucleotides containing unmethylated CpG motifs (ODN-CpG). All groups immunized with the recombinant proteins plus adjuvant: Tc52+c-di-AMP, NTc52+c-di-AMP, CTc52+c-di-AMP, NTc52+c-di-AMP+αGC-PEG, NTc52+CpG, developed significantly higher anti-Tc52 IgG titers than controls. Groups immunized with c-di-AMP and Tc52, NTc52 or CTc52 showed the highest Tc52-specific IgA titers in nasal lavages. All groups immunized with the recombinant proteins plus adjuvant developed a strong specific cellular immune response in splenocytes and lymph node cells with significant differences for groups immunized with c-di-AMP and Tc52, NTc52 or CTc52. These groups also showed high levels of Tc52-specific IL-17 and IFN-γ producing cells, while NTc52+CpG group only showed significant difference with control in IFN-γ producing cells. Groups immunized with c-di-AMP and Tc52, NTc52 or CTc52 developed predominantly a Th17 and Th1immune response, whereas for NTc52+CpG it was a dominant Th1 response. It was previously described that αGC-PEG inhibits Th17 differentiation by activating NKT cells. Thus, in this work we have also included a group immunized with both adjuvants (NTc52+c-di-AMP+αGC-PEG) with the aim to modulate the Th17 response induced by c-di-AMP. This group showed a significant reduction in the number of Tc52-specific IL-17 producing splenocytes, as compared to the group NTc52+c-di-AMP, which has in turn correlated with a reduction in protection against infection. These results suggest that the Th17 immune response developed after immunizing with NTc52+c-di-AMP could have a protective role against T. cruzi infection. Groups NTc52+c-di-AMP, Tc52+c-di-AMP and NTc52PB, were the ones that showed better protection against infection with lower parasitemia and weight loss, and higher survival.

Lipopolysaccharide attached to urban particulate matter 10 suppresses immune responses in splenocytes while particulate matter itself activates NF-κB.

We previously reported that Asian sand dust (ASD), which contains particulate matter (PM) less than 10 μm in diameter (PM10), induced subacute inflammation in splenocytes. However, it was unclear whether the PM itself or compounds attached to its surface induced the inflammation. Here we characterized the role of organic substances adsorbed onto the PM10 surface in triggering inflammation by comparing the effect on splenocyte activation of PM10 from urban areas (urPM10), which is rich in lipopolysaccharide (LPS) as compared to ASD, with that of heated PM10 (H-PM). BALB/c mice were intratracheally administered urPM10 or H-PM with or without LPS (1 ng and 10 ng) four times at 2-week intervals, and splenocytes were prepared at 24 h after the final administration to assay the immune responses. urPM10 suppressed splenocyte activation, while H-PM activated splenocytes and LPS neutralization by polymyxin B rescued urPM10-induced immunosuppression. Co-administration of LPS with H-PM clearly suppressed mitogen-induced immune responses in the spleen. Consistent with these results, H-PM induced the phosphorylation of nuclear factor κB (NF-κB) p65 and I kappa B kinase (IKK), which was inhibited by co-administration of LPS. In mice deficient in the LPS signal transducer MyD88, splenocyte activation after LPS or H-PM treatment in vivo was comparable to that in the control. Altogether, our results indicate that PM10 itself could activate NF-κB through the MyD88 pathway, which was modulated by the amount of LPS attached.

Detection of the mechanism of immunotoxicity of cyclosporine A in murine in vitro and in vivo models.

Transcriptomics in combination with in vitro cell systems is a powerful approach to unravel modes of action of toxicants. An important question is to which extent the modes of action as revealed by transcriptomics depend on cell type, species and study type (in vitro or in vivo). To acquire more insight into this, we assessed the transcriptomic effects of the immunosuppressive drug cyclosporine A (CsA) upon 6 h of exposure of the mouse cytotoxic T cell line CTLL-2, the thymoma EL-4 and primary splenocytes and compared these to the effects in spleens of mice orally treated with CsA for 7 days. EL-4 and CTLL-2 cells showed the highest similarities in response. CsA affected many genes in primary splenocytes that were not affected in EL-4 or CTLL-2. Pathway analysis demonstrated that CsA upregulated the unfolded protein response, endoplasmic reticulum stress and NRF2 activation in EL-4 cells, CTLL-2 cells and primary mouse splenocytes but not in mouse spleen in vivo. As expected, CsA downregulated cell cycle and immune response in splenocytes in vitro, spleens in vivo as well as CTLL-2 in vitro. Genes up- and downregulated in human Jurkat, HepG2 and renal proximal tubular cells were similarly affected in CTLL-2, EL-4 and primary splenocytes in vitro. In conclusion, of the models tested in this study, the known mechanism of immunotoxicity of CsA is best represented in the mouse cytotoxic T cell line CTLL-2. This is likely due to the fact that this cell line is cultured in the presence of a T cell activation stimulant (IL-2) making it more suitable to detect inhibitory effects on T cell activation.

Attenuation of collagen-induced arthritis in mice by salmon proteoglycan.

Rheumatoid arthritis (RA) is a serious autoimmune disease caused by chronic inflammation of connective tissues. The basic principle of RA treatment is aimed to reduce joint inflammation. Our previous studies demonstrated that salmon cartilage proteoglycan (PG) suppresses excess inflammation in different mouse inflammatory diseases. In this study, we investigated the prophylactic effect of PG on the progression of RA using an experimental mouse model, collagen-induced arthritis (CIA). Clinical and histological severity of CIA was attenuated by daily oral administration of PG. In the joints of PG-administered mice, infiltration of macrophages and neutrophils and also osteoclast accumulation were limited. In comparison to nonadministered mice, anti-collagen antibodies in the sera of PG-administered mice did not alter. On the other hand, local expression of interleukin-17A (IL-17A), IL-6, IL-1β, interferon-γ (IFN-γ), C-C chemokine ligand 2 (CCL2), C-X-C chemokine ligand 1 (CXCL1), and CXCL2 in the joints of PG-administered mice decreased. Moreover, in the response of type II collagen- (CII-) restimulation ex vivo, IL-17A and IFN-γ production by splenocytes from PG-administered mice was less than that of control mice. These data suggested that daily ingested PG attenuated CIA pathogenesis by modulating immune response of splenocytes to CII stimulation and local production inflammatory cytokines and chemokines in the joints.

Oral immunization using live Lactococcus lactis co-expressing LACK and IL-12 protects BALB/c mice against Leishmania major infection

Leishmaniasis is a parasitic disease affecting over 12 million individuals worldwide. Current treatments are laborious, expensive, cause severe side effects, and emerging drug resistance has been reported. While vaccination is the most cost-effective means to control infectious diseases there is no human vaccine currently available against Leishmania infections. Lactococcus lactis is a non-pathogenic, non-colonizing Gram-positive lactic acid bacterium commonly used in the dairy industry. Recently, L. lactis was used for the expression and delivery of biologically active molecules, such as antigens and cytokines, in mice and humans. In this study, we report the generation of L. lactis(alr-) strains solely expressing the protective Leishmania antigen, LACK, in the cytoplasm, secreted or anchored to the bacterial cell wall or co-expressing mouse IL-12. We show that oral immunization using live L. lactis, secreting both LACK and IL-12 was the only regimen that partially protected BALB/c mice against subsequent Leishmania major challenge. This highlights the importance of temporal and physical proximity of the delivered antigen and adjuvant for optimal immune priming by oral immunization since co-administration of L. lactis strains independently expressing secLACK and secIL-12 did not induce protective immunity. Protected animals displayed a delay in footpad swelling, which correlated with a significant reduction of parasite burden. Immunization with the L. lactis strain secreting both LACK and IL-12 induced an antigen-specific mucosal immune response and a LACK-specific TH1 immune response in splenocytes and mesenteric lymph node cells. Further, protection in immunized animals correlated with a strong Leishmania-specific TH1 immune response post-challenge, detectable in splenocytes and lymph node cells draining the site of infection. This report demonstrates the use of L. lactis as an oral live vaccine against L. major infection in susceptible BALB/c mice. The vaccine strains generated in this study provide the basis for the development of an inexpensive and safe oral live vaccine against the human parasite Leishmania.

Nanoparticle hydrophobicity dictates immune response.

Understanding the interactions of nanomaterials with the immune system is essential for the engineering of new macromolecular systems for in vivo applications. Systematic study of immune activation is challenging due to the complex structure of most macromolecular probes. We present here the use of engineered gold nanoparticles to determine the sole effect of hydrophobicity on the immune response of splenocytes. The gene expression profile of a range of cytokines (immunological reporters) was analyzed against the calculated log P of the nanoparticle headgroups, with an essentially linear increase in immune activity with the increase in hydrophobicity observed in vitro. Consistent behavior was observed with in vivo mouse models, demonstrating the importance of hydrophobicity in immune system activation.

Age-related effects of sodium arsenite on splenocyte proliferation and Th1/Th2 cytokine production

Aging is associated with immune dysfunction and conditions such as inflamm-aging and immunosuppression. Arsenic, an environmental contaminant distributed worldwide, affects the immune system. This study tested the hypothesis that arsenic has distinct effects on T cell proliferation and the production of cytokines by activated T cells. Murine splenocytes from young (2 months) and aged (24-26 months) C57BL/6 mice were exposed to arsenite (As(3+)), the most toxic form of inorganic arsenic, and stimulated with concanavalin A (Con A) or anti-CD3 antibody. T cell proliferation decreased significantly in response to Con A and anti-CD3 at subtoxic doses of arsenite in splenocytes from both young and aged mice. Arsenite, added concurrently with Con A or anti-CD3, significantly inhibited the production of interleukin-2 (IL-2), interferon-γ (IFN-γ), and interleukin-4 (IL-4) by splenocytes from young mice and significantly reduced the production of IL-10 by splenocytes from aged mice. In contrast, the production of IL-2 and IL-4 by splenocytes from aged mice was only slightly affected by arsenite. The results show that arsenic exposure reduces the immune response in splenocytes. Moreover, this effect may be influenced by aging.

Local treatment with BPPcysMPEG reduces allergic airway inflammation in sensitized mice

According to the hygiene hypothesis, triggering the immune system with microbial components during childhood balances the inherent Th2 bias. In contrast, specific immunotherapy involves exposure of the patient to the allergen in order to achieve desensitization to subsequent contact. In a human in vitro allergy model the potential of the TLR2/6 agonist BPPcysMPEG to modulate antigen presenting cells and allergen-specific immune responses was evaluated. Specific immunomodulation via co-administration of the allergen and BPPcysMPEG enhanced expression of co-stimulatory molecules on DC and increased secretion of the proinflammatory cytokine TNF-α. Acting as an adjuvant, BPPcysMPEG elevated allergen-specific immune responses in co-culture with autologous lymphocytes. Although administration of BPPcysMPEG alone enhanced expression of co-stimulatory molecules on DC, proliferation of autologous lymphocytes was not induced. Based on this finding, the potential of BPPcysMPEG to reduce allergic airway inflammation by preventive modulation of the innate immune system via TLR2/6 agonization was investigated in mice. Local administration of BPPcysMPEG altered cellular influx and cell composition in BAL fluid. Furthermore, the Th2-associated cytokines IL-4 and IL-5 were diminished. Allergen-specific restimulation of cells from mediastinal lymph nodes and splenocytes suggested an alteration of immune responses. The treatment with BPPcysMPEG induced a Th1-dominated cytokine milieu in mediastinal lymph nodes, while allergen-specific immune responses in splenocytes were diminished. The co-administration of allergen and BPPcysMPEG reduced cytokine secretion upon restimulation in mediastinal lymph nodes and splenocytes. From these data we conclude that BPPcysMPEG was able to influence the immune system with regard to subsequent allergen contact by TLR2/6 agonization.

Lidocaine depresses splenocyte immune functions following trauma-hemorrhage in mice

Traumatic and/or surgical injury as well as hemorrhage induces profound suppression of cellular immunity. Although local anesthetics have been shown to impair immune responses, it remains unclear whether lidocaine affects lymphocyte functions following trauma-hemorrhage (T-H). We hypothesized that lidocaine will potentiate the suppression of lymphocyte functions after T-H. To test this, we randomly assigned male C3H/HeN (6-8 wk) mice to sham operation or T-H. T-H was induced by midline laparotomy and approximately 90 min of hemorrhagic shock (blood pressure 35 mmHg), followed by fluid resuscitation (4x shed blood volume in the form of Ringer lactate). Two hours later, the mice were killed and splenocytes and bone marrow cells were isolated. The effects of lidocaine on concanavalin A-stimulated splenocyte proliferation and cytokine production in both sham-operated and T-H mice were assessed. The effects of lidocaine on LPS-stimulated bone marrow cell proliferation and cytokine production were also assessed. The results indicate that T-H suppresses cell proliferation, Th1 cytokine production, and MAPK activation in splenocytes. In contrast, cell proliferation, cytokine production, and MAPK activation in bone marrow cells were significantly higher 2 h after T-H compared with shams. Lidocaine depressed immune responses in splenocytes; however, it had no effect in bone marrow cells in either sham or T-H mice. The enhanced immunosuppressive effects of lidocaine could contribute to the host's enhanced susceptibility to infection following T-H.

Hepatic Granulomas in Murine Visceral Leishmaniasis Caused byLeishmania chagasi

Protozoa belonging to the genusLeishmaniacause the diverse forms of human leishmaniasis, which range from self-healing cutaneous ulcers to widely disseminated or disfiguring disease. Human and murine immune responses to species causing cutaneous and visceral leishmaniasis are considerably different. In murine models of cutaneous leishmaniasis the expansion of distinct CD4+T-cell subsets is associated with either disease prevention (TH1) or disease exacerbation (TH2). However, studies of murine visceral leishmaniasis havenotshown expansion of disease-exacerbating cells during progressive disease. The latter studies have concentrated on immune responses in splenocytes from mice infected with visceralizingLeishmaniaspecies, even though the parasites are found primarily in the livers of infected mice. The histologic response to visceralizingLeishmaniasp. in the liver is one of granuloma formation, which proceeds with similar kinetics in resistant C3H and susceptible BALB/c mice. We isolated hepatic granulomas from BALB/c mice infected for 6 weeks with the visceralizing parasiteL. chagasi.Study of dispersed granuloma cells by FACS andin vitrocultivation with antigen showed differences between the responses of immune cells from the spleens and liver granulomas of these infected animals. A careful dissection of immune responses in hepatic granuloma cells from susceptible or resistant mice infected withL. chagasimay lead to a better understanding of murine immune responses to these important pathogens.

Modulation of antioxidant activities and immune response by food restriction in aging Fisher-344 rats.

Food restriction delays the loss of several cellular immune functions, retards the onset of many diseases during aging and, consequently, extends life span significantly in laboratory rodents. The present study was undertaken to determine whether the age-associated loss in immune function is linked to changes in microsomal and mitochondrial membranes of spleens in Fischer-344 (F-344) male rats. In this study, we determined cytosolic superoxide dismutase activity (SOD), fluidity and cholesterol content in the splenic microsomal and mitochondrial membranes, and DNA synthesis and IL-2 production in spleen cells from young and old ad libitum-fed (AL) and food restricted (FR) rats. The results show that proliferative response to phytohemagglutinin (PHA) and concanavalin A (Con-A) was significantly higher in the spleen cells of 18-month- and 24-month-old FR rats, as compared to their age-matched AL controls. Cytosolic SOD activity in the 24-month-old AL rats decreased by 28% as compared to 6-month-old AL rats, whereas in FR old rats, the loss was only 12%, suggesting that food restriction prevents loss in cytosolic SOD activity in spleens. Our data are consistent with the notion that food restriction modulates loss in immune response of splenocytes by maintaining both cytosolic SOD activity and membrane fluidity during aging.

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Suppressive action of xenogeneic bone marrow cells on antibody formation in spleen cell cultures in vitro

Bone marrow cells from syngenetic and xenogeneic donors of different species were added to splenocyte culture to induce the primary immune response to sheep red blood cells. It has been shown that both xenogeneic and syngeneic bone marrow cells suppress the primary immune response in vitro. A conclusion is made that the suppressant effect exerted by bone marrow cells on the immune response of splenocytes is not liable to xenogenic restriction.