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1.
Host protection against Brucella abortus, is thought to be mediated primarily by a Th1 type immune response. Unfortunately, only few specific bacterial antigens involved in stimulating protective cellular immunity against Brucella are known. Therefore, identifying bacterial proteins that induce a T-lymphocyte mediated response is critical to determine Brucella immunity. Several library screening methods are discussed that have been used to identify Brucella proteins that stimulate T lymphocytes including cellular immunoblotting, Escherichia coli expressed Brucella proteins, green fluorescence reporter systems, and signature tagged mutagenesis. Future studies would likely examine how bacterial proteins expressed within host cells aid pathogen survival and/or induce host responses. Some of these newly identified bacterial gene products may serve as antigens to activate a protective host immune response. Also, identifying Brucella proteins expressed at particular times during infection will also yield insights into Brucella pathogenesis.  相似文献   

2.
The synthetic glucocorticoid, dexamethasone, has been used by investigators studying bovine immune mechanisms to either exacerbate infectious processes or simulate stress-induced steroid-influenced immunosuppression. Considerable differences exist in the literature concerning the effect of dexamethasone on the bovine immune response.The purpose of our study was to clarify the reported effects of dexamethasone on bovine T-lymphocyte function. Therefore, we designed experiments to evaluate cellular and humoral aspects of the bovine immune response under the influence of dexamethasone. The experiments took into consideration the pharmacokinetics of dexamethasone and optimal and suboptimal doses of selected mitogens. The data suggest little variation in hematological parameters that occurred with the administration of dexamethasone. Leukocyte counts were slightly elevated at two observations, and this was believed to be the result of an increase in peripheral blood neutrophils. T-lymphocytes (erythrocyte rosetting) were not selectively depleted. However, suppression of T-lymphocyte function was noted, particularly in response to suboptimum doses of phytohaemagglutinin (PHA) and Concanavalin A (Con A). Antibody production to the T-dependent antigen, KLH, was suppressed in those animals receiving dexamethasone. These data suggest that the immunosuppressive effect of dexamethasone in the bovine is dependent upon the dose of dexamethasone administered, the pharmacological level of dexamethasone in vivo, physiological adaptation of the host, mitogen dose used in evaluation, and the time of evaluation post drug administration. The study points out the importance of considering these variables when interpreting the effects of dexamethasone on the bovine immune response.  相似文献   

3.
Mucosal disease (MD), one sequelae of bovine virus diarrhoea virus (BVDV) infection, causes severe lesions in lymphoid tissues and mucosal surfaces. Lesions are associated with the presence of cytopathogenic (cp) BVDV and initially characterized by apoptotic cell death. The objective of this investigation was to determine if this cell death is mediated only by the cp BVDV, which is known to induce apoptosis in cell culture or if immune-mediated host reactions might also contribute. Early onset MD was experimentally induced in calves by inoculation of persistently viremic calves with a closely related cp BVDV. Calves were euthanized in the early phase of infection between days 5 and 13 post-inoculation and tissues from tonsils, lymph nodes, Peyer's patches, jejunum and colon were collected. Presence of cp BVDV antigen was correlated with distribution of lymphocyte subpopulations in consecutive cryostat sections. In the lymphoid tissues, cp BVDV antigen was predominantly found in the lymphoid follicles. The increase of infected cells with time post-inoculation was paralleled by a decrease of B-lymphocytes and an increase of CD4+ T-lymphocytes. An increased number of CD8+ T-lymphocytes was seen in progressed lesions only. In the intestinal mucosa, initially multifocal, later diffuse infection with cp BVDV was accompanied by a multifocal or diffuse increase of CD4+ T-lymphocytes, respectively. Numbers of IgA+ plasma cells and CD8+ T-lymphocytes were decreased. The common change observed in lymphoid tissues and mucosa was the increase of CD4+ T-lymphocytes in sites with lesions. This might indicate a cell-mediated immune response to the cp BVDV. Besides their helper function to other cells of the immune system, activated CD4+ T-lymphocytes might also exert cytotoxic activity, induce apoptosis in target cells via Fas/Fas ligand binding and thus contribute to the severity of tissue lesions in MD.  相似文献   

4.
Although bovine leukemia virus (BLV) is mainly associated with infections of B-lymphocytes, we have previously reported the statistically significant increase in the T-lymphocytes obtained from BLV-infected asymptomatic aleukemic (AL) cattle. In this report the presence of BLV provirus in the DNA of immunoaffinity purified T-lymphocytes from AL animals was assessed using a highly specific radiolabelled (32P) BLV-DNA provirus probe and solid phase DNA hybridization. The BLV provirus was found in the DNA of the peripheral blood mononuclear cells of all AL animals tested and three of the four purified T-lymphocyte preparations from these animals. The purified T-lymphocyte preparations used in this study contained less than 4% detectable B-lymphocytes. One animal had no detectable B-lymphocytes in the purified T-lymphocyte preparation and the DNA from these cells also gave positive hybridization results. The lymphocyte blastogenesis assay was then used as an indicator of the functional ability of lymphocytes from these BLV-infected AL cattle to respond to mitogenic stimuli. The responsiveness of lymphocytes from these animals to the mitogens concanavalin A (Con A), phytohemagglutinin (PHA), and pokeweek mitogen (PWM) was comparable to that of lymphocytes from BLV-negative animals when changes in 3H-thymidine uptake (c.p.m.) were used as measurement of mitogenic-induced blastogenesis. This indicated that infection of the T-lymphocytes by BLV does not appear to alter the overall response of the lymphocyte populations to mitogenic stimuli. High levels of spontaneous blastogenesis in the absence of mitogenic stimulation were observed for lymphocyte preparations of AL animals. The reason for this proliferation of lymphocytes is unclear; however, sera from these AL animals were found to contain a blastogenesis-augmenting factor(s) when added to lymphocytes from BLV-negative control animals in the presence of Con A, PHA and PWM.  相似文献   

5.
The health and productivity of pigs is important to farmers worldwide. One potential method of improving animal health is by providing functional proteins in the diet, for example spray-dried animal plasma (SDAP). These proteins, particularly plasma IgG, can improve health in many species, including humans. By unspecific activation of the immune system, SDAP can reduce morbidity and mortality as well as improve growth and efficiency what results in reduced costs of production. In this study, the influence of SDAP on expression of T-lymphocyte markers and production parameters in weaned pigs was evaluated. The results showed a significant increase in the percentage of T-lymphocytes, especially the CD8+ subpopulation, as well as a positive effect on body weight gain.  相似文献   

6.
Cats with or without chronic feline immunodeficiency virus (FIV) infection were exposed to feline herpesvirus, type 1 (FHV-1). FIV infected cats became sicker than non-FIV infected cats and required more supportive treatment. However, there were no differences in the length of their illness or in the levels and duration of FHV-1 shedding. FHV-1 infection caused a transient neutrophilia at Day 7 with a rapid return to preinfection levels. The neutrophilia coincided with a transient lymphopenia that was accompanied by a decline in both CD4+ and CD8+ T-lymphocytes. A brief decrease in the CD4+/CD8+ T-lymphocyte ratio occurred at Day 14 in both FIV infected and non-infected cats. This decrease was mainly the result of an absolute and transient increase in CD8+ T-lymphocytes. CD4+ and CD8+ T-lymphocyte numbers and CD4+/CD8+ T-lymphocyte ratios returned to baseline within 4-8 weeks in both FIV infected and non-infected cats. FIV infected cats produced less FHV-1 neutralizing antibodies during the first 3 weeks of infection than non-FIV infected animals. The IgM FHV-1 antibody response was depressed in FIV infected cats whereas the IgG antibody response was unaffected. FHV-1 infection evoked a comparable transient loss of lymphocyte blastogenic responses to concanavalin A and pokeweed mitogen in both FIV infected and non-infected cats. However, response to pokeweed mitogen took longer to return to normal in FIV infected animals. Lymphocytes from FIV infected cats had a greater and more sustained proliferative response to FHV-1 antigen than non-FIV infected cats. The ongoing IgG antibody response to FIV was not affected by FHV-1 infection.  相似文献   

7.
Six week old BDF1 female mice were exposed to cadmium chloride in the drinking water at concentrations ranging from 0 to 50 micrograms/mL cadmium for three weeks. The humoral immune response against sheep red blood cells which is T-lymphocyte and macrophage dependent, was suppressed in a dose dependent fashion with the maximum suppression of 28.2% observed in the highest exposure group (P less than 0.0001). Mitogen studies demonstrated that cadmium was a weak mitogen, producing a dose-dependent enhancement of blastogenesis (P = 0.026). T-lymphocyte responses which were induced by concanavalin A were not affected by cadmium exposure (P = 0.284). A dose-dependent enhancement of the B-lymphocyte activity was produced in the presence of cadmium when the lymphocytes were induced with Escherichia coli, lipopolysaccharide, a B-lymphocyte mitogen (P = 0.007). These results suggest that the immunosuppressive effects of cadmium associated with the humoral immune response are not due to an impairment of lymphocyte proliferation, an intermediate step involved in the generation of an immune response. The immunosuppressive effects were produced at relatively low cadmium exposures as indicated by the renal cadmium concentrations suggesting that the immune systems is very vulnerable to the toxic effects of cadmium.  相似文献   

8.
Immune response in hormonally-induced prostatic hyperplasia in the dog   总被引：1，自引：0，他引：1  
We induced prostatic enlargement in castrated dogs using either androgen alone or androgen combined with estrogen. In addition to previously reported hyperplastic changes, marked infiltration with immune effector cells was observed. This mononuclear cell infiltrate was phenotypically characterized using CD3 as pan T-lymphocyte marker, CD79 for B-lymphocytes, MAC378 for macrophages, and antibodies against kappa- and lambda-immunoglobulin (Ig) light chains for plasma cells. The majority of inflammatory cells (>80%) in the mononuclear infiltrates were T-lymphocytes and the numbers correlated with the degree of inflammation. The B-lymphocytes were found particularly in areas with marked follicular formation and diffuse infiltration, whereas there were only a few positive cells (<10%) in areas with a moderate or slight inflammation. Macrophages were found primarily in areas with atrophic and cystic changes with and without inflammation. The expression of lambda-Ig-positive cells depended on the degree of inflammation (5-10%), whereas immunoreactivity of kappa-Ig did not correlate with the extent of inflammatory reaction. Our present findings together with the evaluation of longitudinal biopsies of hormonally-induced BPH indicate that hyperplasia preceded cell-mediated and humoral immune response.  相似文献   

9.
Twelve month old female BDF1 mice were exposed to cadmium chloride in the drinking water at concentrations ranging from 0 to 50 micrograms/mL cadmium for 26 days. The humoral immune response against sheep red blood cells, a T-lymphocyte dependent response, was evaluated during the last five days of the exposure period. The antibody response was not suppressed by cadmium exposure (P = 0.661). Weight gains (P = 0.205) and water consumption (P = 0.378) during the exposure period were also unaffected. These results indicate that the immunosuppressive effects of cadmium which have been documented in younger, more immunologically competent mice were masked by the natural age-related immunosuppression that was observed in this study. Immunotoxicological investigations in aged animal models appear to be a poor indicator of immune dysfunction in the general population.  相似文献   

10.
Fifty-seven monoclonal antibodies (mAb) selected after the first round analyses in the Third International Swine CD workshop for their possible reactivity with T-lymphocyte specific antigens were further analysed in a second round. As target cells for flow cytometric analyses served peripheral blood mononuclear cells, nylon-wool enriched T-lymphocytes, thymocytes, splenocytes, and lymphocytes derived from Peyer's patches. These second round analyses revealed 15 different data sets. Together with 22 pre-selected data sets from the first round analyses with the whole panel of monoclonal antibodies, 37 data sets were used for the clustering of the respective mAb. Using the LTDB4 program, 19 preliminary clusters could be defined. Two clusters (C3 and C7) with 4 mAb showed no labelling of resting T-lymphocytes. Seven clusters (C1, C2, C4, C5, C6, C11, and C12) contain mAb (in total: 16 mAb) directed against subsets of CD4(-)CD8(-) T-lymphocytes. These mAb seem to recognise antigens on porcine T-lymphocytes with T-cell receptor (TcR) gamma/delta chains. Three clusters (C8, C9, C10, C13) seem to be artificial. They contain either mAb staining CD4(-)CD8(-) T-lymphocytes and low CD8+ cells (C8, C9), mAb with various reactivity (C10) and mAb with known differences in their reactivity (C13). Cluster C14 contains 3 mAb against the CD4a-epitope, C15 describes mAb directed against porcine CD8c-epitope whereas mAb against CD8a and CD8b-epitopes grouped in C19. The mAb found in C16 seem to recognise CD45R. Cluster C17 is composed of different standards directed against CD2, CD3, CD5 and wCD6. Two additional mAb recognising the CD2a-epitope could be enclosed. C18 contains two mAb directed against SWC2.  相似文献   

11.
Equine protozoal myeloencephalitis (EPM) is one of the most common neurologic diseases of horses in the United States. The primary etiologic agent is Sarcocystis neurona. Currently, there is limited knowledge regarding the protective or pathophysiologic immune response to S. neurona infection or the subsequent development of EPM. The objectives of this study were to determine whether S. neurona infected horses with clinical signs of EPM had altered or suppressed immune responses compared to neurologically normal horses and if blood sample storage would influence these findings. Twenty clinically normal horses and 22 horses with EPM, diagnosed by the presence of S. neurona specific antibodies in the serum and/or cerebrospinal (CSF) and clinical signs, were evaluated for differences in the immune cell subsets and function. Our results demonstrated that naturally infected horses had significantly (P<0.05) higher percentages of CD4 T-lymphocytes and neutrophils (PMN) in separated peripheral blood leukocytes than clinically normal horses. Leukocytes from naturally infected EPM horses had significantly lower proliferation responses, as measured by thymidine incorporation, to a non-antigen specific mitogen than did clinically normal horses (P<0.05). Currently, studies are in progress to determine the role of CD4 T cells in disease and protection against S. neurona in horses, as well as to determine the mechanism associated with suppressed in vitro proliferation responses. Finally, overnight storage of blood samples appears to alter T lymphocyte phenotypes and viability among leukocytes.  相似文献   

12.
Cats were injected subcutaneously with viable Mycobacterium bovis (BCG), and immune responses were evaluated at various times after injection. The BCG injection produced fever, leukocytosis, neutrophilia, and lymphadenopathy of regional lymph nodes. Intradermal tuberculin injection produced responses consistent with delayed type hypersensitivity reaction in the treated cats at postinoculation day 21. Skin responses to tuberculin were not significant at postinoculation day 49. The cellular infiltrate at the tuberculin injection site at 48 hours after injection was an admixture of polymorphonuclear cells and mononuclear cells. The BCG produces strong intradermal skin responses in the cat, but the response was not long-lived as in cattle and guinea pigs. The BCG injection did not produce significant changes in the absolute total lymphocyte and absolute T-lymphocyte numbers in peripheral blood. The percentage of T-lymphocytes was significantly higher in the BCG-treated group. Differences were not observed in lymphocyte blastogenesis with tuberculin and non-specific mitogens between BCG-treated and control cats.  相似文献   

13.
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14.
Comparative flow microfluorimetric (FMF) analysis was used to identify and characterize 27 monoclonal antibodies (MoAbs) reactive with bovine T-lymphocytes. Determinants present on all circulating T-lymphocytes were recognized by 11 MoAbs, 8 of which blocked E rosette formation. Determinants present on only the BoCD4+ T-lymphocyte subset were detected by 9 MoAbs, while determinants restricted to the BoCD8+ T-lymphocyte subset were recognized by 7 MoAbs. Competitive labeling experiments demonstrated that determinants recognized by subset-specific MoAbs were present on BoCD4 or BoCD8 molecules. Comparative studies revealed that some determinants, both pan-T specific and subset-specific, were conserved on homologous (orthologous) molecules expressed on leukocytes from other species of ruminants. Polymorphism was evident with several determinants.  相似文献   

15.
Immunisation of Balb/c mice against Babesia rodhaini by an amicarbalide-controlled infection resulted in a solid immunity which lasted for 216 days. With spleen cells of immune mice protection could be transferred both to naive mice pretreated with cyclophosphamide. Treatment of naive mice with cyclophosphamide (300 mg/kg) five days before a lethal B. rodhaini inoculation resulted in over 50% survival. This protective effect of cyclophosphamide is explained by its inhibiting effect on suppressor T-cells. The protection against B. rodhaini challenge infection afforded to immune Balb/c mice was completely resistant to a sublethal irradiation of 400 rad. Since B-lymphocyte function in antibody production is suppressed by this dose, the role of antibodies in the effector phase of the immunity appears to be of minor if any importance. A considerable degree of protection was still preserved after irradiation of immune animals with 875 rad. Sensitivity to this irradiation dose of all immunocompetent cells except macrophages and a small fraction of T-lymphocytes indicates the involvement of these cell types in the effector phase of the specific immunity. Highly radioresistant macrophages are therefore considered to play the major role but T-lymphocytes are also required for complete protection.  相似文献   

16.
The effect of glucan, a biological response modifier of yeast origin, on different immune functions was studied after the intramuscular application in goats. The simultaneous administration of glucan with human serum albumin or tetanus toxoid significantly stimulated the antibody production to both antigens differing in their thymus dependency. Similarly, the phagocytizing activity of the blood polymorphonuclear leukocytes measured by the reductase colorimetric assay significantly increased one week after the glucan treatment. However, suppression of T-lymphocyte function in experimental animals was determined by the lymphocyte transformation test particularly in response to phytohemagglutinin and concanavalin A. The results of the study indicate that glucan can modulate some elements of the ruminant immune response.  相似文献   

17.
Salmonellosis due to Salmonella enterica serovar Abortusovis (S. Abortusovis) is mainly characterized by abortion in sheep. Little is known about the immune response, which develops in the host as a result of infection. We evaluated the immune response of pregnant ewes vaccinated and successively exposed to full virulent S. Abortusovis. We found that vaccine constituted by inactivated S. Abortusovis induced both humoral and cellular-mediated immune response and that it provided protection against a challenge infection due to a fully virulent S. Abortusovis. Furthermore, we found an association between the lack of capability to produce IFN-gamma and abortion. This evidence suggests that protection against abortion can be associated to an IFN-gamma mediated mechanism. Our findings represent an interesting insight to better understand the interplay between host and S. Abortusovis and the effector mechanisms underpinning immune-based protection.  相似文献   

18.
Acquired myasthenia gravis (MG) is a disorder of neuromuscular transmission in which muscle weakness results from an autoantibody mediated depletion of acetylcholine receptors (AChR) at the neuromuscular junction. Experimental autoimmune myasthenia gravis, described in rodents and rabbits, has provided a good model of the effects of the autoimmune response against AChR and has shown that the specificities of the immune response in MG are those that would be obtained by immunization with native AChR. It has provided little information, however, about what initiates and sustains the immune response in MG. Acquired MG occurs spontaneously in dogs and may be the most common neuromuscular disorder that can be diagnosed in this species. As in human MG, an autoimmune response against AChR has been demonstrated and AChR autoantibodies have been implicated in the pathogenesis. The variability in clinical presentation, methods of diagnosis, and occurrence with other autoimmune diseases and neoplasia are identical to that of humans. Future studies of spontaneous canine autoimmune MG may provide clues to the determination of what factors initiate and sustain the autoimmune response to AChR, and in the study of specific suppression of the autoimmune response against AChR.  相似文献   

19.
Specific immunity in mice to heartwater   总被引：1，自引：0，他引：1  
Mice develop a specific immune response following infection with the mice strains of heartwater. In the case of the Kümm strain the agent can persist in some tissues for up to 365 days. Transfer of spleen cells from immune mice confers protection against homologous challenge in recipient mice showing that cell mediated immunity is important. A comparison with immune mechanisms occurring in other Rickettsia is discussed.  相似文献   

20.
The identification and the numeration of the lymphocytes in cattle is realized essentially by revealing the membranary properties of these cells: receptors for some lectins (i.e. peanut agglutinin or phytohemagglutinin), receptors for sheep red blood cells (SRBC), surface-specific antigens concerning T-lymphocytes and surface immunoglobulins concerning B-lymphocytes. The technique of the production in the goat of a specific anti-bovine T-lymphocyte antiserum (GABTA) is described. The GABTA shows a specific cytotoxic activity on 55% of the peripheral blood lymphocytes and more than 95% of the thymocytes. It inhibits, at 90%, the formation of the rosetting with SRBC. This reagent allows identification and a common and quick numeration of the T-lymphocytes in cattle.  相似文献   

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