Antigen Sheep Red Blood Cells Research Articles

Immune stress and facultative sex in a parasitic nematode

Abstract It has been suggested that sexual reproduction in parasites may be advantageous because it helps evade genotype-specific host immune responses. Indirect support for this hypothesis has recently come from work on Strongyloides ratti, a parasitic nematode of rats that develops and reproduces sexually or asexually. In this species, host immune responses against S. ratti lead to a higher proportion of individuals reproducing sexually. However, an alternative explanation for these results is that sex is favoured by general environmental stress, including host responses against antigen sources other than S. ratti. Here we test this hypothesis, by determining how host immunity against two other parasitic nematode species (Nippostrongylus brasiliensis & Strongyloides venezuelensis) and commonly used mammalian antigens (sheep red blood cells) affects the likelihood of S. ratti larvae developing sexually. Our results show that increased levels of sex occur in response to immune responses generated against these other species, and not just host immunity elicited by S. ratti. This is consistent with the idea that sex is favoured under stressful conditions, and does not support the immune evasion hypothesis.

Feeding Regimen, Dietary Vitamin E, and Genotype Influences on Immunological and Production Traits of Broilers

Many functional changes occur during the first 2 wk after a broiler hatches, a period that continues to be an increasing proportion of a broiler's life. Breeding programs are designed to produce a broiler with high potential for growth, yield, and feed efficiency, traits that may compromise health status under husbandry designed to maximize this genetic potential. This experiment compared performances of two broiler lines differing in growth and yield, when reared to 12 days of age under full and diluted feeding regimens containing three dietary levels of vitamin E. Traits measured included body weight (BW), feed efficiency, and allomorphic measures of breast, shank, spleen, bursa, heart, gizzard, ceca, and lung. For bilateral traits, asymmetries were measured. Data were obtained for mortality, response to sheep red blood cell antigen, heterophils, lymphocytes, and response to an E. coli challenge. Responses to dietary feed restrictions and levels of dietary vitamin E during the first 12 days after hatch were noted at market age. There was a trade-off between growth- and health-related traits with responses to husbandry programs, age, sex, and genetic line.

Immunomodulating activity of a polysaccharide isolated from Mori Cortex Radicis.

The immunomodulating activity of a polysaccharide isolated from Morus alba (PMA) root bark was examined in murine splenic lymphocytes. PMA enhanced proliferation of splenic lymphocytes in a synergistic manner in the presence of mitogens. However, PMA suppressed primary IgM antibody production from B cells, which was activated with lipopolysaccharide, a polyclonal activator, or immunized with a T-cell dependent antigen sheep red blood cells. Our observations showed that the immunomodulating activity of PMA increased lymphocyte proliferation and that PMA decreased antibody production from B cells, which was distinct from those of other plant-originated polysaccharides.

Enhanced immune function does not depress reproductive output

Costs of reproduction might be mediated by a physiological (resource allocation) trade-off between immune function and reproductive effort, and several recent studies have shown that an experimental increase in reproductive effort is associated with decreased immune function. Here we test the complementary prediction of this hypothesis: that increased immune function (specific antibody production) depresses reproductive output. Female European starlings (Sturnus vulgaris) were injected with a non-pathogenic antigen (sheep red blood cells) following completion of laying of their first clutch, to stimulate an in vivo humoral immune response (primary antibody production). We induced laying of a second clutch by removing the first clutch, and assessed changes in reproductive performance in individual females pre- and post-treatment. Injection of sheep red blood cells produced a significant antibody response in 96% (n=29) of treated females, with titres comparable to previous studies (range 1 to 7). However, increased antibody production did not decrease primary or secondary female reproductive effort (re-laying interval, egg size, clutch size, chick growth or fledging success), compared with control, saline-injected birds (n=22). These data do not support a simple resource allocation model for the cost of reproduction, based on a reciprocal, negative relationship between resources allocated to immune function and reproduction.

THE HEMOLYTIC PLAQUE-FORMING CELL ASSAY IN TILAPIA (OREOCHROMIS NILOTICUS) EXPOSED TO BENZO[a]PYRENE: ENHANCED OR DEPRESSED PLAQUE FORMATION DEPENDS ON DOSING SCHEDULE

The prospect of utilizing the cichlid teleost tilapia (Oreochromis niloticus) as an alternative experimental model to mammals for preliminary chemical immunotoxicity risk assessment is being evaluated by examining the National Toxicology Program's standard battery of rodent immunotoxicity assays in chemicaltreated tilapia. The present report examines the hemolytic plaque forming cell assay (PFC), a quantitative indicator of antibody production, in tilapia exposed to the polycyclic aromatic hydrocarbon (PAH) benzo[a]pyrene (B[a]P). Reduced antibody production against sheep red blood cell (SRBC) antigen in response to B\[a]P was observed using the PFC assay, via reduction in plaque number. Under specific immunization circumstances, increased plaque formation was observed in chemical-exposed fish, an effect also reported in rodents. Although the normal teleost immune responsiveness was weaker than seen with mice under comparable conditions (presumably due to differences in antibody structure of teleosts), ti...

Mode of inheritance of unselected traits in lines of chickens selected for high or low antibody response to sheep red blood cells. 2. Heterophils, lymphocytes, and hematocrits

The nuclear lines for this experiment were White Leghorns that had undergone long-term selection for high (HH) or low (LL) antibody response to sheep red blood cell antigen(s). Sixteen progeny types consisting of parental lines, reciprocal F1 and F2 crosses, and backcrosses were produced in a single hatch from age-contemporary parents. At 30 d of age, blood was obtained from a random sample of 10 males per progeny type (n = 160) and slides prepared for subsequent determination of number of heterophils and lymphocytes. Twelve days later, blood was collected from random samples of 10 males and 10 females per progeny type (n = 320) for measuring hematocrits. There were no differences between parental lines for heterophils, lymphocytes, or the heterophil:lymphocyte ratio. Reciprocal effects were evident in the F1 crosses and directional heterosis was present in one cross but not the other. Neither maternal heterosis nor recombination effects were significant for either heterophils or lymphocytes. Although hematocrits were similar for males and females and parental lines, sex-linked and recombination effects appeared to be important.

Mode of inheritance of unselected traits in lines of chickens selected for high or low antibody response to sheep red blood cells. 1. Resistance to marble spleen disease virus and juvenile body weight

Two lines of White Leghorns that had undergone long-term selection for high (HH) or low (LL) antibody response to sheep red blood cell antigen(s) formed the nuclear lines for this experiment. Matings were made in a full diallel cross to produce in a single hatch from age-contemporary breeders the parental lines, reciprocal F1 and F2 crosses, and backcrosses for 16 progeny types. For males and females, there were parental line differences in BW to 42 d of age, after which there was decline between lines for males. Differences in BW between reciprocal F1 crosses and maternal heterosis declined with age, primarily reflecting dissipation of effects of egg weight. Heterosis of BW was dependent on the particular F1 cross and recombination effects were not important. At 50 d of age chicks were inoculated with either a 1 or 10% suspension of spleen extract from chickens infected with marble spleen disease virus (MSDV). A third group served as uninjected controls. Response to MSDV was evaluated by spleen weight 6 d after inoculation. Spleen weights relative to BW of control chicks were heavier for the HH than LL line with evidence from the crosses of sexlinkage and negative heterosis. Line LL chicks were more resistant to MSDV than Line HH chicks was F1 crosses intermediate to and different from either parental line with no evidence of heterosis.

Diet and Humoral Responsiveness of Lines of Chickens Divergently Selected for Antibody Response to Sheep Red Blood Cells

Growth and humoral immune response were studied in lines of white leghorn chickens selected for high (HA) or low (LA) 5-day antibody titers to an i.v. inoculation with 0.1 ml of a 0.25% suspension of sheep red blood cells (SRBC) antigen(s). Chicks were fed either a high (E) or low (A) nutrient density diet from hatch onward. Chicks from each line-diet subclass were inoculated i.v. with 0.1 ml of either 0.25% or 2.50% suspension of SRBC at either 7, 14, 21, or 28 days of age. Antibody titers were measured 5, 10, and 20 days after inoculation. LA chicks were heavier than HA chicks at 7 days of age and thereafter. Chicks fed diet E were heavier than those fed diet A. Feed efficiency was influenced by diet (E > A) at 21 and 28 days of age and line (LA > HA) at 28 days of age. In all but one case, antibody titers to SRBC were higher in HA than LA chicks. Also, the frequency of nonresponders of chicks inoculated with SRBC at 7 days of age was higher for LA than HA chicks. The higher dosage elicited greater 5-day antibody responses in LA but not in HA chicks inoculated at 28 days of age. Dietary effects on SRBC antibody were generally unimportant except for occasional interactions of dosage and line.

Lung lymphocytes proliferate minimally in the murine pulmonary immune response to intratracheal sheep erythrocytes.

The importance of in situ lymphocyte proliferation for net accumulation of lung lymphocytes during pulmonary immune responses and in immunologic lung diseases remains uncertain. Accordingly, we studied the experimental pulmonary immune response of antigen-primed C57BL/6 mice to intratracheal challenge with the particulate antigen sheep red blood cells. Uptake of nucleotide analogs (bromodeoxyuridine in vivo and tritiated thymidine in vitro), expression of the cell activation antigens CD25 and CD69 by flow cytometry, and response to the antimitotic agent hydroxyurea (in vivo) were measured. Although many lung lymphocytes and CD4+ T cells were CD25+ and CD69+, indicating recent activation, all techniques demonstrated that lung lymphocytes proliferated minimally in vivo. Blockade of cell division by hydroxyurea administration for 24 h did not significantly decrease lung lymphocyte accumulation on Day 3 after challenge. Lung lymphocytes also proliferated minimally in vitro (even on macrophage removal and despite addition of exogenous interleukin [IL]-2 or IL-4). However, lung lymphocytes responded vigorously to mitogens (immobilized anti-CD3, phytohemagglutinin, or concanavalin A), excluding global unresponsiveness to restimulation. Thus, in this model of pulmonary immunity, accumulation of lung lymphocytes does not require local T-cell proliferation and presumably depends instead on recruitment.

Potential use of cytokine therapy in poultry

Newly hatched chickens are highly susceptible to infection during the first 2 weeks of life. The utilisation of cytokines as therapeutic agents in livestock animals, in particular poultry, has become more feasible with the recent cloning of cytokine genes and the progression of new technologies such as live vectors. We have constructed a live recombinant fowlpox virus (FPV) that expresses chicken myelomonocytic growth factor (fp/cMGF). Administration of fp/cMGF to chicks resulted in a marked and sustained increase in the number of circulating blood monocytes as well as an increase in their state of activation, as measured by enhanced phagocytic activity and elevated production of nitric oxide. We have recently cloned the gene for chicken interferon- γ (ChIFN- γ). Recombinant ChIFN- γ was capable of protecting chick fibroblasts from undergoing virus-mediated lysis and induced nitrite secretion from chicken macrophages in vitro. Preliminary vaccination trials have indicated that co-administration of ChIFN- γ with antigen (sheep red blood cells) resulted in enhanced secondary (IgG) antibody responses and allowed a 10-fold lower dose of antigen to be used. Furthermore, administration of ChIFN- γ resulted in enhanced weight gain in chicks and improved their resistance to disease challenge. The ability of cytokines to combat infection and enhance vaccine efficacy makes them excellent candidates as a therapeutic agents and adjuvants.

Impact of cage density on pullet performance and blood parameters of stress

The effects of cage density on pullet live performance and blood indices of stress were evaluated in two commercial White Leghorn strains housed at 38, 32, 26, and 20 birds per cage from Day 1 to 6 wk of age, and 19, 16, 13, and 10 birds per cage from 6 to 18 wk. Cage densities of 26 and 13 birds per cage represent a U.S. standard of 142 and 284 cm2 per bird that is often applied in commercial pullet rearing. Cage density treatments include confounding cage, feeder, and drinker spaces per bird as might be encountered in commercial practice when growing more pullets per cage. Body weight was significantly reduced at greater bird densities in both strains; however, one strain was affected as early as 6 wk of age, whereas in the other strain, body weight was not reduced significantly until 18 wk. Feed intake was increased by more than 13% in both strains at the lowest density treatment (20 birds per cage) from Day 1 to 2 wk but reduced by more than 9% by higher cage densities during the remainder of the study. Feed conversion (FC) ratio was similarly improved (i.e., reduced) when more pullets were housed per cage, and increased when fewer birds were placed per cage compared to the standard. Despite a significant reduction in feed intake and a corresponding loss of body weight, cage density treatments had no significant affect on hemagglutinin titers to sheep red blood cell antigen, percentage heterophils (H), lymphocytes (L), or the H:L ratio. However, pullet age and strain differences were observed for all blood parameters. Overall, treatments allowing more cage, feeder, and drinker spaces per bird than the U.S. commercial standard provided no body weight advantage, and allowed for greater feed intake and poorer FC at several ages.

Low toxicity and high antitumour activity of Daunomycin by conjugation to an immunopotential amphoteric branched polypeptide

The acid labile derivative of Daunomycin cis-aconityl Daunomycin (cAD), was coupled to an amphoteric polypeptide, poly[Lys-(Glui-dl-Alam)] (EAK), which was selected for conjugation on the basis of its pharmacological and immunological properties. The systemic toxicity of covalently attached Daunomycin was studied by monitoring body weight, life-span, bone marrow and haematological parameters of BDF1 mice. More than 3-fold the lethal dose of free Daunomycin could be applied without serious toxic effect when the drug was attached to EAK. The dose- and time-dependent modulatory effect of free drug and [cAD]–EAK conjugate on the humoral and cellular immune response to sheep red blood cell antigens in mice was studied. The conjugation of Daunomycin to EAK carrier polypeptide compensated for the immunosuppression induced by free Daunomycin. [cAD]–EAK conjugate at Daunomycin doses of 2–10mg/kg was very effective against L1210 leukaemia producing 66–100% long-term survivors (>60 days), while Daunomycin in itself increased the mean survival only by 52%, with no long-term survivors. The mixture of free Daunomycin and EAK polypeptide had similar toxicity and antitumour activity as free Daunomycin, indicating the important role of covalent attachment in increased therapeutic efficacy.

Antibody transmitting ability of hens from lines of chickens differing in response to SRBC antigen

1. Hens from White Leghorn lines selected for high (HA) or low (LA) antibody response to sheep red blood cells (SRBC) were inoculated with 0.1 ml of either 0.25% or 2.50% SRBC suspension. Eggs laid over the next 15 d were grouped into 5, 3‐d collection periods and incubated. Maternal antibody titres were determined in chicks at hatch and 7 d after hatch. 2. In a subsequent experiment, hens of the 2 lines were inoculated with 0.1 ml of 2.50% suspension of SRBC, and eggs laid on days 10 to 13 after inoculation were incubated. Maternal antibody titres were determined in 15 and 18‐d embryos as well as in chicks at 0, 5, 10, 15, 20, and 25 d after hatch. 3. Dosage of SRBC had no effect on the antibody titres in line HA; however, the higher dosage elicited greater antibody titres than the lower dosage in line LA. 4. Maternal antibodies were detected earlier in chicks of line HA (eggs laid on days 7 to 9) than those of line LA (eggs laid on days 10 to 12) regardless of dosage administered to the hens. 5. In both lines, antibodies specific to SRBC were observed on day 15 of incubation, with the frequency of responders greatest at hatch. The high frequency of HA responders was maintained for 15 d after hatch, whereas there was an immediate decline with age in LA responders. 6. It was concluded that lines HA and LA have diverged in the pattern of maternal antibody levels as a result of the divergent selection for antibody response to SRBC.

Selective immunomodulatory activity of SK&F 106615, a macrophage-targeting antiarthritic compound, on antibody and cellular responses in rats and mice

The azaspiranes are novel immunomodulators which are effective in a variety of animal models of autoimmune disease and transplantation. The compounds appear to target macrophages and alter their functional activity. One of these compounds, SK&F 106615 (N,N-diethyl-8,8-dipropyl-2-azaspiro[4.5]decane-2-propanamine dihydrochloride), is now in phase II clinical trials for rheumatoid arthritis. As many drugs/compounds effective in autoimmune disease and transplantation are overtly immunosuppressive, we designed studies to show that SK&F 106615 has selective immunomodulatory effects and that it does not perform in a manner characteristic of classical immunosuppressive agents on immune function. SK&F 106615 inhibited mouse and rat spleen cell and rat peripheral blood mononuclear cell proliferation in vitro with an IC50 of 500 nM. In vivo, treatment of C57BL/6 mice (15 mg/kg/day, i.p.) or rats (20 mg/kg/day, p.o.) for 2 weeks had no effect on specific antibody synthesis to ovalbumin (OVA) compared to rapamycin (RAP) which completely suppressed the antibody response. Compared to cyclosporin A (CsA), FK 506 and RAP which suppressed the antibody (plaque forming) response to particulate (sheep red blood cells) antigen in a dose responsive manner, SK&F 106615 administered at a dose of 50 mg/kg was inactive. There was an inhibition of the proliferative response of lymph node cells from treated mice and rats to mitogen and antigen in ex vivo assays. SK&F 106615, but not RAP, induced cells in the spleens of mice that could inhibit normal spleen cell proliferation in a co-culture assay. Thus, a selective immunomodulatory effect can be shown for SK&F 106615 in the absence of generalized immunosuppression.

Impact of Alternate-Day Feeding Cycles on Immune and Antibacterial Responses of White Leghorn Chicks

White Leghorn cockerels helped measure the effect of number of cycles of alternate-day feeding (food restriction of 24 hr fast and 24 hr full-feed per cycle) on immune and antibacterial responses assessed after inoculation with E. coli or sheep red blood cell (SRBC) antigen. Chicks fed ad libitum had a more severe response to E. coli challenge than those on alternate-day feeding regimens. SRBC antibody titers were highest in chicks exposed to several cycles of alternate-day feeding and least for the 1-day fasted chicks.

Antibodies to morphine as indicators of chronic morphine intoxication and impaired immune reactivity

Chronic morphine treatment of rats for 2 and 4 weeks led to an increase in morphine-binding cells in the spleen, despite the general reduction of mononuclear cell content in the spleen and thymus. Simultaneously, serum antibodies to morphine (AbM) in haemagglutination titres 1:20 and higher appeared in 50% and 80% of animals, respectively. Animals with high titres of AbM had much weaker immune response to a thymus-dependent antigen (sheep red blood cells). In humans chronic opiate intoxication was accompanied by significant reduction of functional activity of T-lymphocytes, which was especially dramatic in addicts with high levels of antibodies to morphine: high incidence of infection was obvious in the latter group. Results suggest that high levels of antibodies to morphine serve as indicators, not only of chronic morphine intoxication, but of impaired immune reactivity, especially involving T-cell functional activity.

Immunoresponsiveness of fast-growing chickens as influenced by feeding regimen.

1. Immunoresponsiveness and disease resistance were measured in broiler males maintained on ad libitum feeding throughout or on alternate-day feeding. Alternate-day restrictions were started 1 and 2 d after hatch so that on any one day there were chicks fed and fasted. 2. Severity of response to E. coli challenge as measured by lesion scores, and mortality was greater for chicks fed ad libitum than those fed on alternate days. For chicks fed on alternate days, lesion scores were lower for those without access to feed for the 24-h period immediately after challenge. 3. Spleen weights, the indicator of response to marble spleen disease virus challenge, were higher for chicks fed ad libitum than those fed on alternate days. 4. Antibody response to sheep red blood cell antigen was not affected by feeding regimen. 5. Ratios of heterophils to lymphocytes were higher for chicks given access to feed for the previous 24-h period than for those fasted during the previous 24-h or those that had been fed ad libitum. 6. Results of this experiment suggest that for alternate-day feeding programs, vaccination be administered on the day that chicks are not fed.

In vivo indomethacin reverse exercise-induced immunosuppression in rats

The effect of oral indomethacin on the immunosuppressive effect of exercise was examined in exercised untrained female Wistar rats immunized with sheep red blood cell (SRBC) antigens. Intensity of the 1 h exercise was controlled by 0–50 kPa air pressure, generated by a compressor located at the bottom of a water tank, during continuous swimming of the rats, previously immunized with SRBC. After 48–72h, depending on the ip (intraperitoneal) or iv (intravenous) route of SRBC immunization, the exercise suppressed humoral PFC response and augmented phagocytosis of peritoneum macrophages. These effects occurred only when exercise was performed at 48 h after antigen injection. Animals receiving indomethacin, however, did not show any exercise-related suppression of the PFC response. The data suggest a relationship between exercise-induced immunosuppression and possible increased in vivo prostaglandin synthesis during the intense exercise. Overall, exercise-related suppression of humoral PFC response was dependent on the intensity of the exercise, was time specific, and was reversible by pharmacological blockade of the cyclooxygenase pathway of prostaglandin synthesis.

Interleukin 12 inhibits antigen-induced airway hyperresponsiveness, inflammation, and Th2 cytokine expression in mice.

Allergic asthma is characterized by airway hyperresponsiveness and pulmonary eosinophilia, and may be mediated by T helper (Th) lymphocytes expressing a Th2 cytokine pattern. Interleukin (IL) 12 suppresses the expression of Th2 cytokines and their associated responses, including eosinophilia, serum immunoglobulin E, and mucosal mastocytosis. We have previously shown in a murine model that antigen-induced increases in airway hyperresponsiveness and pulmonary eosinophilia are CD4+ T cell dependent. We used this model to determine the ability of IL-12 to prevent antigen-induced increases in airway hyperresponsiveness, bronchoalveolar lavage (BAL) eosinophils, and lung Th2 cytokine expression. Sensitized A/J mice developed airway hyperresponsiveness and increased numbers of BAL eosinophils and other inflammatory cells after single or repeated intratracheal challenges with sheep red blood cell antigen. Pulmonary mRNA and protein levels of the Th2 cytokines IL-4 and IL-5 were increased after antigen challenge. Administration of IL-12 (1 microgram/d x 5 d) at the time of a single antigen challenge abolished the airway hyperresponsiveness and pulmonary eosinophilia and promoted an increase in interferon (IFN) gamma and decreases in IL-4 and IL-5 expression. The effects of IL-12 were partially dependent on IFN-gamma, because concurrent treatment with IL-12 and anti-IFN-gamma monoclonal antibody partially reversed the inhibition of airway hyperresponsiveness and eosinophilia by IL-12. Treatment of mice with IL-12 at the time of a second antigen challenge also prevented airway hyperresponsiveness and significantly reduced numbers of BAL inflammatory cells, reflecting the ability of IL-12 to inhibit responses associated with ongoing antigen-induced pulmonary inflammation. These data show that antigen-induced airway hyperresponsiveness and inflammation can be blocked by IL-12, which suppresses Th2 cytokine expression. Local administration of IL-12 may provide a novel immunotherapy for the treatment of pulmonary allergic disorders such as atopic asthma.

In vivo study of the immunomodulating activity of om-85 using the plaque-forming cells technique (PFC) in mice

The activity of increasing oral doses of the bacterial extract OM-85 was determined by using the plaque-forming cells assay in mice. The results showed that the oral administration of OM-85 significantly increased the number of splenic antibody-secreting cells against sheep red blood cells (antigen) compared with controls. A maximal response was reached between 400 and 800 mg/kg body weight, and was reproducible with the different batches of OM-85 used. This study indicates that the oral administration of the immunomodulator allows the activation of splenic B-lymphocytes, probably through the gut-associated lymphoid tissue.