Spleen Mononuclear Cells Research Articles

A new epitope on sheep CD45R molecule detected by a monoclonal antibody

This paper describes the production and characterization of a monoclonal antibody (mAb), Co-46D5, which recognizes a new epitope on the isoform of the homologous sheep leukocyte common antigen (LCA) or CD45. This mAb was submitted to the 3rd workshop on ruminant leukocyte antigens and was assigned to a cluster reactive with B- and T-cells subsets. Co-46D recognizes a 220 kDa molecule on peripheral blood mononuclear cells (PBMC) and spleen cells but not on thymocytes. Flow cytometry (FCM) analysis shows that Co-46D5 reacted with 30% of PBMC and 50% of spleen cells and more than 95% of cells freshly isolated from lymphoid follicles of the ileal Peyer's patches (IPP) of young lambs. By immunohistochemistry, the antigen was detected mainly on B-cell areas of lymph nodes and spleen. It was also found on a subpopulation of medullar thymocytes. Based on these results, we assume that Co-46D5 recognizes a new epitope on the largest isoform of the sheep CD45 receptor, probably on the homologous to the human CD45RA isoform.

Quantitative analysis of cytokine gene expression in the liver.

The relative levels of cytokine gene expression in the liver were analysed, focusing on IL-2, IL-4, IL-5, IL-6 and IFN-gamma compared to those in the spleen and Peyer's patch by using the reverse transcriptase polymerase chain reaction (RT-PCR). The levels of expression of cytokines in the liver mononuclear cells (MNC). especially that of IL-6, were significantly higher than in other organs when mice were reared under specific pathogen-free (SPF) or conventional conditions. Both the spleen and Peyer's patch MNC expressed little of any of the cytokines, except for IL-4 in Peyer's patch MNC. The liver MNC produced significant amounts of IL-6 in the culture supernatant upon concanavalin A stimulation. These findings suggest that the liver is a potent IL-6-producing organ, which may relate to B cell differentiation, liver regeneration and the induction of acute phase proteins.

Effects of chronic mild stress (CMS) and imipramine administration, on spleen mononuclear cell proliferative response, serum corticosterone level and brain norepinephrine content in male mice.

There is increasing evidence that stress and emotional reactions produce changes in various immune processes. These changes may be due to alterations of the stress responses endocrine and for autonomic mediating mechanisms. In order to study such effects, the impact of chronic mild stress (CMS) application, and of subsequent imipramine administration were studied on the spleen mononuclear cell proliferative response period. OFI strain male mice were subjected to 4 or 7 weeks of CMS. The effects of these treatments on serum corticosterone levels and hypothalamic and hippocampal norepinephrine (NE) contents were also assessed. Subjects submitted to CMS had a higher spleen mononuclear cell proliferative response after either treatment duration. Imipramine treatment diminished this response enhancement in CMS exposed animals, but did not alter the proliferative responses of control subjects. Serum corticosterone levels, as well as hypothalamic and hippocampal nonrepinephrine contents did not significantly vary between groups. Taken together, these results suggest that CMSs effects on immune reactivity are not related to serum glucocorticoids or NE changes in these locations associated with the hypothalamic-pituitary- adrenocortical (HPA) axis.

Gene Expression of the Hematopoietic Cell Phosphatase in Juvenile Myelomonocytic Leukemia

We analyzed the relative expression of Hematopoietic cell phosphatase (HCP) in mononuclear cells (MNC) of peripheral blood (PB), bone marrow (BM) and spleen of patients with juvenile myelomonocytic leukemia (JMML) and normal donors. Two regions of HCP with alternative exon skipping of exon 6 or exon 12 are described. There was no difference in the expression of the amplified HCP cDNA regions in MNC of JMML patients compared to normal donors. The two forms of exon skipping were present in unstimulated MNC of JMML patients or normal donors. In contrast, phytohemagglutinin (PHA) stimulated MNC of normal donors, Epstein-Barr Virus (EBV) transformed B-cells of JMML patients, BFU-E and CFU-GM derived colonies of JMML patients, and the cell lines K562 and HEL did not or only barely express these two forms of exon skipping. These results may indicate that alternative HCP exon skipping may be associated with the proliferative state of the cell.

Induction of immunomodulating cytokines by a new polysaccharide–peptide complex from culture mycelia of Lentinus edodes

The immunomodulating effect of a new polysaccharide–peptide complex from culture mycelia of Lentinus edodes (LE) was studied for elucidation of the mechanism of augmentation of cell-mediated immunity. RNA samples were isolated from the untreated and treated murine splenocytes and human peripheral blood mononuclear cells. RT-PCR was used to analyze the cytokine gene expression and bioassay was used to analyze the cytokine production. By administration of LE, the expression levels of IL-2 and TNF-α genes were augmented in the treated murine spleen mononuclear cells and human peripheral blood mononuclear cells. The production of IL-2 were augmented in the treated murine spleen mononuclear cells, and the production of TNF-α were augmented in the treated murine peritoneal exudate macrophages. The production of IL-2 and TNF-α were augmented in the treated human peripheral blood mononuclear cells. These results suggest that LE may induce Th immune responses.

Inhibition of experimental autoimmune encephalomyelitis in Lewis rats by nasal administration of encephalitogenic MBP peptides: synergistic effects of MBP 68-86 and 87-99.

Induction of mucosal tolerance by inhalation of soluble peptides with defined T cell epitopes is receiving much attention as a means of specifically down-regulating pathogenic T cell reactivities in autoimmune and allergic disorders. Experimental autoimmune encephalomyelitis (EAE) induced in the Lewis rat by immunization with myelin basic protein (MBP) and Freund's adjuvant (CFA) is mediated by CD4+ T cells specific for the MBP amino acid sequences 68-86 and 87-99. To further define the principles of nasal tolerance induction, we generated three different MBP peptides (MBP 68-86, 87-99 and the non-encephalitogenic peptide 110-128), and evaluated whether their nasal administration on day -11, -10, -9, -8 and -7 prior to immunization with guinea pig MBP (gp-MBP) + CFA confers protection to Lewis rat EAE. Protection was achieved with the encephalitogenic peptides MBP 68-86 and 87-99, MBP 68-86 being more potent, but not with MBP 110-128. Neither MBP 68-86 nor 87-99 at doses used conferred complete protection to gp-MBP-induced EAE. In contrast, nasal administration of a mixture of MBP 68-86 and 87-99 completely blocked gp-MBP-induced EAE even at lower dosage compared to that being used for individual peptides. Rats tolerized with MBP 68-86 + 87-99 nasally showed decreased T cell responses to MBP reflected by lymphocyte proliferation and IFN-gamma ELISPOT assays. Rats tolerized with MBP 68-86 + 87-99 also had abrogated MBP-reactive IFN-gamma and tumor necrosis factor-alpha mRNA expression in lymph node cells compared to rats receiving MBP 110-128 nasally, while similar low levels of MBP-reactive transforming growth factor-beta and IL-4 mRNA expressing cells were observed in the two groups. Nasal administration of MBP 68-86 + 87-99 only slightly inhibited guinea pig spinal cord homogenate-induced EAE, and passive transfer of spleen mononuclear cells from MBP 68-86 + 87-99-tolerized rats did not protect naïve rats from EAE. Finally, we show that nasal administration of MBP 68-86 + 87-99 can reverse ongoing EAE induced with gp-MBP, although higher doses are required compared to the dosage needed for prevention. In conclusion, nasal administration of encephalitogenic MBP peptides can induce antigen-specific T cell tolerance and confer incomplete protection to gp-MBP-induced EAE, and MBP 68-86 and 87-99 have synergistic effects. Non-regulatory mechanisms are proposed to be responsible for tolerance development after nasal peptide administration.

Dose-dependent mechanisms relate to nasal tolerance induction and protection against experimental autoimmune encephalomyelitis in Lewis rats.

Nasal administration of soluble antigens is an exciting means of specifically down-regulating pathogenic T-cell reactivities in autoimmune diseases. The mechanisms by which nasal administration of soluble antigens suppresses autoimmunity are poorly understood. To define further the principles of nasal tolerance induction, we studied the effects of nasal administration of myelin basic protein (MBP) on experimental autoimmune encephalomyelitis (EAE) in the Lewis rat. EAE is a CD4+ T-cell-mediated animal model for human multiple sclerosis. Nasal administration of guinea-pig (gp)-MBP at a dose as low as 30 micrograms/rat can completely prevent gp-MBP-induced EAE, whereas nasal administration of bovine (b)-MBP is not effective even at a much higher dosage. Cellular immune responses, as reflected by T-cell proliferation and interferon-gamma (IFN-gamma)-ELISPOT, were suppressed in rats receiving the two different doses (30 and 600 micrograms/rat) of gp-MBP, but not after administration of b-MBP. Rats tolerized with both doses of gp-MBP had also abrogated MBP-induced IFN-gamma mRNA expression in popliteal and inguinal lymph node mononuclear cells compared with rats receiving phosphate-buffered saline nasally. However, adoptive transfer revealed that only spleen mononuclear cells from rats pretreated with a low dose, but not from those pretreated with a high dose, of gp-MBP transferred protection to actively induced EAE. Low-dose (30 micrograms/rat) gp-MBP-tolerized rats also had high numbers of interleukin-4 (IL-4) mRNA-expressing lymph node cells, while high-dose (600 micrograms/rat) gp-MBP-tolerized rats had low numbers of IL-4 mRNA-expressing lymph node cells. Our data suggest an exquisite specificity of nasal tolerance. Dose-dependent mechanisms also relate to nasal tolerance induction and protection against EAE in the Lewis rat.

The pattern of cytokine gene expression in lymphoid organs and peripheral blood mononuclear cells of mice with experimental allergic encephalomyelitis

We previously observed Th1-dominated response in the central nervous system (CNS) of mice during the course of experimental allergic encephalomyelitis (EAE) with a semiquantitative reverse transcriptase–polymerase chain reaction (RT/PCR) analysis. We report here that mRNA levels for both inflammatory cytokines including interleukin (IL)-l β, IL-2, IL-6, interferon (IFN)- γ, tumor necrosis factor (TNF)- α and TNF- β and immunoregulatory cytokines including IL-4, IL-10 and transforming growth factor (TGF)- β were up-regulated in the preclinical and/or acute phase but down-regulated in the recovery phase of EAE in lymph node (LN) of mice. Similar profiles for cytokine mRNA levels were also observed in spleen and peripheral blood mononuclear cells (PBMC). The present study also showed that a significant down-regulation of the mRNA level for IL-6 in the acute phase as compared with the preclinical phase, and a significant reduction of the mRNA level for TGF- β in the preclinical and acute phase as compared with the corresponding mRNA levels in the control mice treated with complete Freund's adjuvant alone were characteristic in peripheral immune organs of mice with EAE. These results indicate that no particular bias in cytokine production occurred in peripheral immune organs of mice with actively induced relapsing EAE, and that the relative reduction in production of TGF- β or IL-6 in peripheral circulation might participate in the induction or remission of EAE, respectively. Our results using the animal model of multiple sclerosis (MS) suggested that the mRNA levels for IL-6 and TGF- β in PBMC from patients with MS may be a good indicator to assess the disease activity or to predict relapse.

Linomide suppresses acute experimental autoimmune encephalomyelitis in Lewis rats by counter-acting the imbalance of pro-inflammatory versus anti-inflammatory cytokines

Linomide (quinoline-3-carboxamide) is a synthetic immunomodulator that suppresses several experimental autoimmune diseases. Here we report the effects of Linomide on experimental autoimmune encephalomyelitis (EAE), a CD4 + T cell-mediated animal model of multiple sclerosis (MS). EAE induced in Lewis rats by inoculation with homogenized guinea pig spinal cord and Freund's complete adjuvant was strongly suppressed by Linomide administered daily subcutaneously from the day of inoculation. Linomide dose-dependently delayed the interval between immunization and onset of clinical EAE, and reduced severity of EAE symptoms. These clinical effects were associated with dose-dependent down-modulation of myelin antigens-induced T cell responses and by suppression of the proinflammatory cytokines IFN- γ and TNF- α, and upregulation IL-4, IL-10 and TGF- β as evaluated by in situ hybridization for mRNA expression in spleen mononuclear cells and spinal cord sections. These findings suggest that Linomide could be useful in certain T cell dependent autoimmune diseases.

Fasciola hepatica-Induced Immune Suppression of Spleen Mononuclear Cell Proliferation: Role of Nitric Oxide

The aim of the present study was to evaluate the proliferative response of spleen mononuclear cells (Spm) to mitogens in rats infected withFasciola hepaticaand its correlation with Spm and peritoneal cell (PC) nitric oxide (NO) production on Days 1, 3, 7, 14, 30, and 60 postinfection. In addition, histological changes in the liver were also studied. The proliferative response to Con A ofF. hepatica-infected Spm was significantly decreased on Day 7 postinfection (P< 0.01). However, a pronounced increase of the proliferative response was detected from Day 3 until Day 60 when Spm were stimulated with LPS. In order to determine whether NO levels were modified duringF. hepaticainfections, we quantified nitrite in Spm and PC supernatants in cultures. Our results indicate a profound decrease of nitrite production by LPS-stimulated PC on the first and second weeks postinfection, and an increase in the levels of this mediator on LPS-stimulated Spm at the same postinfection time. TheF. hepaticaexcretory-secretory antigen (ESA) was in part involved in the decrease of nitrite production by LPS-stimulated PC. A mechanism to avoid an immune response during the first stages of liver penetration could explain the transient suppression observed in Spm proliferative responses. On the other hand, the decrease in NO production by rat-infected PC could also be one of the strategies of the parasite to avoid the potential killing effect of NO during peritoneal migration.

Low CD83, but normal MHC class II and costimulatory molecule expression, on spleen dendritic cells from HIV+ patients.

Dendritic cells (DCs), which are the most potent antigen-presenting cells for T lymphocytes, are targets for HIV in vitro and in vivo. Antigen presentation by DCs has been suggested to be impaired during HIV infection; however, the extent to which DCs from HIV+ individuals are altered, particularly in lymphoid organs where T cell stimulation takes place, is not clear. To address this question, the levels of expression of functionally important molecules by spleen DCs from HIV+ patients (n = 6), and HIV- organ donors (n = 5) were compared. By rare event analysis of flow cytometry data, spleen DCs from HIV+ patients were not depleted, representing 0.6 +/- 0.4% of spleen mononuclear cells compared with 0.8 +/- 0.5% in HIV- spleens. Fresh HIV+ spleen DCs were MHC II+ and weakly CD86+CD40+, but negative for CD83 and CD80, and hence had a normal phenotype, showing no signs of in vivo activation. After 24 hr of culture, they upregulated the expression of MHC II, CD40, CD80, and CD86 to levels just as high as those on DCs from organ transplant donors. However, cultured DCs from HIV+ spleens showed lower expression of CD83, compared with DCs from HIV- spleens. The biological significance of this observation will be appreciated further when the function of this molecule is better known. These results suggest that putative defects in antigen presentation by DCs from HIV+ patients are not related to the surface expression of MHC II, CD40, CD80, or CD86.

Active suppression induced by cutaneous exposure to bacterial superantigen is prevented by interleukin-12 treatment in vivo.

Exposure to the bacterial superantigen staphylococcal enterotoxin B (SEB) leads to inhibition of several immune responses and the induction of regulatory cells. The aim of this study was to characterize these regulatory cells further and to investigate the effect of interleukin-12 (IL-12) on superantigen-induced suppression. For this purpose BALB/c mice were injected subcutaneously with low doses of SEB that did not deplete the SEB-reactive V beta T cells. Intravenous transfer of unseparated local-draining lymph node cells from these SEB-treated animals suppressed the proliferative response of mononuclear spleen cells of naive syngeneic recipients for at least 3 weeks. The regulatory cells did not produce the type 2 cytokines, interleukin-4 (IL-4) or interleukin-10 (IL-10), or increased amounts of transforming growth factor-beta (TGF-beta). Depletion of CD8+ or SEB-reactive V beta 7+ and V beta 8+ T cells, prior to transfer, abrogated the suppressive effect. Intraperitoneal injections of IL-12 into donors, prior to SEB treatment, prevented the induction of functional regulatory cells, and treatment of recipients with IL-12, prior to receipt of cells from SEB-treated donors, prevented the suppressive effect of regulatory cells that were already induced. The data indicate that exposure to minute amounts of superantigens directly induces superantigen-reactive and CD8+ regulatory T cells and that superantigen-induced suppression can be prevented and reversed by IL-12 treatment in vivo.

Lack of Involvement of Nitric Oxide in the Macrophage-Mediated Inhibition of Spleen Cell Proliferation during Experimental Cryptococcosis

We investigated the proliferative response to mitogens of spleen mononuclear (Spm) cells fromCryptococcus neoformans-infected rats. We determined reactive oxygen intermediates (ROI) and nitric oxide (NO) production by peritoneal and Spm cells, and evaluated the correlation of the proliferative response with NO and ROI production. The proliferative response of Spm cells from infected rats dramatically decreased at 14 and 21 days postinfection (PI). The unresponsiveness of Spm cells from 14-day infected rats was not abrogated by the addition of L-NAME and AG, indicating that NO is not involved in the antiproliferative response of experimental cells. When SOD, catalase, and indomethacin were added to the cultures, the suppression was still observed, indicating that ROI and prostaglandins are not involved in the unresponsiveness of lymphocytes. The proliferative response of lymphocytes from 14-day infected rats was significantly improved when cultures were made in the presence of Con A and exogenous IL-2. Additionally, a purified T-rich fraction from infected rats cultured with control macrophages recovered the normal proliferative response. This result indicates that macrophages from infected rats mediate the unresponsiveness of lymphocytes, probably by reducing the ability of lymphocytes to secrete IL-2.

Purification of galectin-3 from ovine placenta: developmentally regulated expression and immunological relevance.

Galectins, beta-galactoside-binding lectins, are extensively distributed in the animal kingdom and share some basic molecular properties. Galectin-3, a member of this family, is generally associated with differentiation, morphogenesis, and metastasis. In this study, galectin-3 was isolated from ovine placental cotyledons round the middle of the gestation period by lactose extraction followed by affinity chromatography on lactosyl-agarose, and separated from galectin-1 by size exclusion chromatography on a Superose 12 column. Under native conditions this lectin behaved as a monomer with an apparent molecular weight of approximately 29,000 and an isoelectric point of 9.0. The partial amino acid sequence of the peptides obtained by tryptic digestion of this protein followed by HPLC separation showed striking homology with other members of the galectin-3 subfamily. Furthermore, ovine placental galectin-3 exhibited specific mitogenic activity toward rat spleen mononuclear cells. Besides, this protein strongly reacted with a rabbit antiserum raised against a chicken galectin. Results obtained by Western blot analysis showed that its expression was greatly decreased in term placenta with respect to the middle of the gestation period, suggesting a regulated expression throughout development.

Nasal administration of myelin basic protein prevents relapsing experimental autoimmune encephalomyelitis in DA rats by activating regulatory cells expressing IL-4 and TGF- β mRNA

This study explores nasal administration of myelin basic protein (MBP) as a potential means of inducing tolerance to relapsing experimental autoimmune encephalomyelitis (PR-EAE), an experimental multiple sclerosis (MS) model that was induced in DA rats by immunization with rat spinal cord homogenate and incomplete Freund's adjuvant. DA rats received a total dosage of 0, 6, 60, 600 μg/rat of bovine MBP on ten consecutive days prior to immunization. EAE with typical course was observed in control rats receiving only PBS nasally, and in rats receiving 6 μg/rat of MBP. Rats receiving 60 μg/rat of MBP developed acute EAE but no relapse during 60 days of observation post immunization (p.i.). Only one of eight rats receiving 600 μg/rat of MBP developed slight, transient EAE. This protection was confirmed at the histology level and was associated with decreased levels of MBP-reactive IFN- γ secreting Th1-like spleen cells on day 13 and 60 p.i. Rats receiving 60 and 600 μg/rat of MBP showed decreased serum anti-MBP IgG2b antibody levels on day 60 p.i., and rats receiving 600 μg/rat of MBP had marginally increased anti-MBP IgG1 antibody levels in serum compared to control EAE rats. Cytokine mRNA profiles in central nervous system (CNS) and spleen mononuclear cells were evaluated. Dose-dependent reduction of TNF- α mRNA expression were observed both in CNS and in splenocytes. Increased IL-4 and TGF- β mRNA expression were observed in CNS of low (6 μg/rat) and median (60 μg/rat) dose of MBP tolerized rats and in splenocytes of rats tolerized with 600 μg/rat of MBP. We conclude that nasal administration of MBP in DA rat prevents EAE induced by immunization with whole rat spinal cord homogenate that, besides MBP, contains multiple antigenic myelin proteins. A mechanism involving MBP-reactive regulatory cells expressing IL-4 and TGF- β mRNA acts as part in the induction of this tolerance.

Modulation by serum glucose levels on morphine-induced antinociceptive effect in C57BL/KsJ-db/db mice

The role of serum glucose levels on the sensitivity to the antinociceptive effect of morphine in streptozotocin-induced diabetic mice and C57BL/KsJ db/db mice were examined. The sensitivity to the antinociceptive effect of morphine was significantly reduced in streptozotocin-induced diabetic mice as compared with age-matched non-diabetic mice. Pretreatment with insulin (3 U/kg, s.c.) significantly reduced the serum glucose levels of streptozotocin-induced diabetic mice as compared with those of untreated diabetic mice. However, post-drug (morphine) tail-flick latency was not affected by pretreatment with insulin. The antinociceptive effect of morphine was also significantly reduced in C57BL/KsJ-db/db mice as compared with age-matched control mice. When CS-045 was administered to C57BL/KsJ-db/db mice, the serum glucose levels were significantly reduced. There was no significant difference in the antinociceptive effect of morphine between CS-045-treated C57BL/KsJ-db/db mice and C57BL/KsJ-db/++ mice. Adoptive transfer of supernatant of the spleen cell homogenate from C57BL/KsJ-db/db mice to naive ICR mice had no significant effect on the recipients' antinociceptive sensitivities to s.c. morphine. These findings support the our previous suggestion that some factor(s) derived from spleen mononuclear cells is the prime factor involving the insulin-insensitive mechanisms for the reduction of μ-opioid agonist-induced antinociception during the severe stages of diabetes.

Cross‐reactive cellular immune responses in chickens vaccinated with live infectious bronchitis virus vaccine

Summary Two‐week‐old chickens were vaccinated intra‐nasally with a live infectious bronchitis virus (IBV) vaccine (H120). On days 4, 7, 11 and 14 post‐vaccination (p.v.) spleen mononuclear cells (MNC) prepared from control and vaccinated chickens were stimulated in vitro with homologous (strain M41) and heterologous (strains 7 and 793/B) virus antigens. Antigen‐specific lymphoproliferation and interleukin‐2 (IL‐2) and interferon‐y (IFN) production were used to measure cross‐reactive cell mediated immune responses. In antigen‐specific lymphoproliferation assays, it was found that while 4/16 vaccinated birds responded to the homologous antigen, only one responded to an heterologous antigen (strain 7). However, IL‐2 production was seen in the supernatants of spleen MNC from vaccinated chickens stimulated with all three antigens. Production of IFN was also demonstrated in samples stimulated with the homologous and one heterologous (strain 7) antigen. Thus it appears that, following vaccination of chickens with live IBV vaccine, cross‐reactive cellular immune responses occur that vary in magnitude with the strain of IBV used for in vitro stimulation.

Specific inhibition of lymphocyte proliferation and induction of apoptosis by CLL-I, a beta-galactoside-binding lectin.

Beta-galactoside-binding lectins or galectins are a family of closely related carbohydrate-binding proteins which functions still remain to be elucidated. Several evidence suggest they could play a role in different biological processes, such as cell growth regulation and immunomodulation. In the present study we report that affinity-purified CLL-I (chicken lactose lectin-I), an acidic 16-kDa galectin exhibits specific growth regulatory properties. Con A-stimulated rat spleen mononuclear cells showed a marked dose-dependent growth inhibition upon incubation with the galectin protein. Cell growth arrest was highly prevented by galectin-specific sugars. In addition, biochemical, cytofluorometrical, and morphological evidence are also provided to show that these inhibitory properties are related to a positive control in the apoptotic threshold of spleen mononuclear cells. Flow cytometric analysis showed a dose- and time-dependent increase of cells with hypodiploid DNA content upon exposure to CLL-I. Moreover, cells treated with CLL-I displayed the typical ultrastructural changes compatible with apoptosis, mainly chromatin condensation and margination along the inner surface of the nuclear envelope. Finally, the highly characteristic "ladder" pattern of DNA fragmentation into oligonucleosome-length fragments of approximately 180-200 bp could be found within 6 h of cell culture with CLL-I, mainly in the T cell-enriched population. Induction of apoptosis by a beta-galactoside-binding protein highlights a potentially novel mechanism for regulating the immune response and points to a rational basis for the postulated immunomodulatory properties of this protein family.

Experimental Measles. II. Infection and Immunity in the Rhesus Macaque

Measles infection and the host immune response to measles virus were compared using naive and immunized rhesus monkeys. The monkeys were experimentally challenged with a wild-type strain of measles virus inoculated intranasally. After pathogenic virus challenge, measles virus was detected in mononuclear cells of peripheral blood, lymph node, and spleen in naive monkeys and viremia peaked on Day 7. However, only one of five vaccinated monkeys had a low virus titer in peripheral blood mononuclear cells at one time point after challenge. No virus was detected in the lymphoid tissues from an immunized monkey that was euthanized on Day 7 of infection. Measles-specific IgM, IgG, neutralizing antibody, and cytotoxic T lymphocytes were detected in vaccinated monkeys before challenge, but antibody titers were significantly lower in immunized monkeys than in naive monkeys after challenge. Measles-specific IgG antibody and cytotoxic T cell responses were still detected more than 1 year after vaccination or infection. This animal model is useful for the further study of measles pathogenesis, immunosuppression, and immunologic memory.

Inhibition of spleen cell proliferative response to mitogens by excretory-secretory antigens of Fasciola hepatica

The effect of Fasciola hepatica excretory-secretory antigen (ESA) on the proliferative response of spleen mononuclear (SpM) cells of normal rats to stimulation with mitogens has been examined. When ESA was added to normal SpM cells, there was a decrease in the proliferative response to concanavalin A (Con A) or lipopolysaccharide (LPS) in a dose-dependent manner. The addition of indomethacin, which blocks prostaglandin synthesis, or Nω-nitro- l-arginine methyl ester ( l-NAME) a specific inhibitor of nitric oxide (NO) synthase, had no effect on the ability of ESA to suppress the proliferative response to Con A. However, supplementation of the culture media with catalase, which degrades hydrogen peroxide (H 2O 2) or superoxide dismutase (SOD) to remove superoxide anion (O 2 −), resulted in a restoration of proliferation to Con A. When LPS was used as mitogenic stimulus no inhibitor added to the culture restored the proliferation. These results suggest that H 2O 2 and O 2 − are involved in the suppressor phenomenon induced by ESA in the T-cell proliferative events.