The nature of the thymus dependency of mucosal mast cells. II. The effect of thymectomy and of depleting recirculating lymphocytes on the response to Nippostrongylus brasilliensis.

The effect of adult thymectomy and of lymphocyte depletion by thoracic duct drainage on the jejeunal mucosal mast cell (MMC) response to infestation with Nippostrongylus brasiliensis has been studied in rats. Adult thymectomy 2 to 4 weeks before infestation with the parasite had no effect on the production of MMC hyperplasia. However, long-term thymectomy (12–39 weeks) produced a progressive decline in the MMC response to infestation. When adult-thymectomized rats were depleted of recirculating lymphocytes by thoracic duct drainage, infestation either 2 weeks or 12 weeks after completion of drainage significantly reduced the MMC response. The MMC response was restored to normal when the animal's washed thoracic duct lymphocytes were returned to it, and could be regenerated over the course of 12 weeks in the presence of thymus tissue. It is concluded that the thymus influences MMC indirectly, through the production of peripheral T lymphocytes, and that the T-lymphocyte subset involved belongs to the long-lived recirculating pool.     

The role of mast cell degranulation products in mast cell hyperplasia. I. Mechanism of action of nerve growth factor

A variety of mast cell degranulating agents have previously been shown to induce mast cell hyperplasia in adult rats. In neonates 2.5 S nerve growth factor (NGF) induces a hyperplasia of both mucosal and connective tissue mast cells (MMC and CTMC). We have examined the role of the potent mast cell degranulating properties of NGF on its ability to induce mast cell hyperplasia. Administration of NGF in combination with the mast cell stabilizing agent disodium cromoglycate was found to abrogate the CTMC hyperplasia induced by NGF alone. Treatment of neonatal rats with the alternate degranulating agent compound 48/80 was found to induce a limited CTMC but not a MMC hyperplasia. A supernatant obtained by degranulating purified adult rat peritoneal mast cells with anti-IgE was found to induce hyperplasia of the CTMC population similar to that observed with NGF administration. However, this degranulation product supernatant only induced a limited MMC hyperplasia as judged by RMCP II content of the tissues. These results suggest that NGF has dual action inducing mast cell hyperplasia; CTMC hyperplasia being dependent on the ability of NGF to degranulate mast cells. MMC hyperplasia induced by NGF is independent of CTMC degranulation. Degranulation products from peritoneal mast cells act to increase both MMC and CTMC populations in the neonate. These data suggest that the CTMC population may be regulated by an autocrine positive feedback mechanism in vivo.     

Danger signals and nonself entity of tumor antigen are both required for eliciting effective immune responses against HER-2/neu positive mammary carcinoma: implications for vaccine design

Using parental FVB mice and their neu transgenic counterparts, FVBN202, we showed for the first time that dangerous hyperplasia of mammary epithelial cells coincided with breaking immunological tolerance to the neu "self" tumor antigen, though such immune responses failed to prevent formation of spontaneous neu-overexpressing mammary carcinoma (MMC) or reject transplanted MMC in FVBN202 mice. On the other hand, neu-specific immune responses appeared to be effective against MMC in parental FVB mice because of the fact that rat neu protein was seen as "nonself" antigen in these animals and the protein was dangerously overexpressed in MMC. Interestingly, low/intermediate expression of the neu "nonself" protein in tumors induced immune responses but such immune responses failed to reject the tumor in FVB mice. Our results showed that self-nonself (SNS) entity of a tumor antigen or danger signal alone, while may equally induce an antigen-specific immune response, will not warrant the efficacy of immune responses against tumors. On the other hand, entity of antigen in the context of dangerous conditions, i.e. abnormal/dangerous overexpression of the neu nonself protein, will warrant effective anti-tumor immune responses in FVB mice. This unified "danger-SNS" model suggests focusing on identification of naturally processed cryptic or mutated epitopes, which are considered semi-nonself by the host immune system, along with novel dangerous adjuvant in vaccine design.     

S. mansoni Bolsters Anti-Viral Immunity in the Murine Respiratory Tract

The human intestinal parasite Schistosoma mansoni causes a chronic disease, schistosomiasis or bilharzia. According to the current literature, the parasite induces vigorous immune responses that are controlled by Th2 helper cells at the expense of Th1 helper cells. The latter cell type is, however, indispensable for anti-viral immune responses. Remarkably, there is no reliable literature among 230 million patients worldwide describing defective anti-viral immune responses in the upper respiratory tract, for instance against influenza A virus or against respiratory syncitial virus (RSV). We therefore re-examined the immune response to a human isolate of S. mansoni and challenged mice in the chronic phase of schistosomiasis with influenza A virus, or with pneumonia virus of mice (PVM), a mouse virus to model RSV infections. We found that mice with chronic schistosomiasis had significant, systemic immune responses induced by Th1, Th2, and Th17 helper cells. High serum levels of TNF-α, IFN-γ, IL-5, IL-13, IL-2, IL-17, and GM-CSF were found after mating and oviposition. The lungs of diseased mice showed low-grade inflammation, with goblet cell hyperplasia and excessive mucus secretion, which was alleviated by treatment with an anti-TNF-α agent (Etanercept). Mice with chronic schistosomiasis were to a relative, but significant extent protected from a secondary viral respiratory challenge. The protection correlated with the onset of oviposition and TNF-α-mediated goblet cell hyperplasia and mucus secretion, suggesting that these mechanisms are involved in enhanced immune protection to respiratory viruses during chronic murine schistosomiasis. Indeed, also in a model of allergic airway inflammation mice were protected from a viral respiratory challenge with PVM.     

Cryosurgery of the rabbit prostate. Comparison of the immune response of immature and mature bucks

The intensity and specificity of the immune response developed following each of three independent in situ freezing insults of the coagulating gland (anterior prostate) of immature male rabbits have been compared to that obtained following similar cryostimulation of the coagulating gland of mature bucks by the methods of tanned cell haemagglutination and gel diffusion precipitation. Results of this study offer confirmation to the previously demonstrated secondary or anamnestic immune response observed following multiple freezing of the rabbit coagulating gland and indicate further that the size and physiological status of the coagulating gland, i.e., the concentration of coagulating gland secretory autoantigens, are among the important variables in determining the cryosensitivity of a given animal. This cryosensitivity may be of particular significance in the prospective treatment of patients with prostatic cancer by cryoimmunotherapy. That is, the development of an immune response in such patients may reasonably be related to the concentration and subsequent release of prostatic tumourspecific or tumour-associated antigens.     

Condition-dependent alteration of cellular immunity by secondary symbionts in the pea aphid,Acyrthosiphon pisum

Endosymbionts can fundamentally alter host physiology. Whether such changes are beneficial or detrimental to one or both partners may depend on the dynamics of the symbiotic relationship. Here we investigate the relationship between facultative symbionts and host immune responses. The pea aphid, Acyrthosiphon pisum, maintains an obligate primary symbiont, but may also harbour one or more facultative, secondary symbionts. Given their more transient nature and relatively recent adoption of a symbiotic lifestyle compared to primary symbionts, secondary symbionts may present a challenge for the host immune system. We assessed the response of several key components of the cellular immune system (phenoloxidase activity, encapsulation, immune cell counts) in the presence of alternative secondary symbionts, investigating the role of host and secondary symbiont genotype in specific responses. There was no effect of secondary symbiont presence on the phenoloxidase response, but we found variation in the encapsulation response and in immune cell counts based largely on the secondary symbiont. Host genotype was less influential in determining immunity outcomes. Our results highlight the importance of secondary symbionts in shaping host immunity. Understanding the complex physiological responses that can be propagated by host-symbiont associations has important consequences for host ecology, including symbiont and pathogen transmission dynamics.     

A polyhedrosis virus forming polyhedra in midgut-cell nucleus of silkworm, Bombyx mori. II. Chemical nature of the virion

A number of tumorlike lesions of the ctenidia and mantle of the freshwater bivalve Dreissena polymorpha are described. The lesions are not considered to be neoplasms and are similarly not attributable to any of the known parasites of Dreissena. No visible signs of external injury to the affected organs could be detected and it is considered that the granulomas are the result of the hemocyte response of the animal to traumatic irritation or to bacterial infection. The bacteria may be of primary or merely of secondary importance. In the extreme cases examined the granulomas comprised internally a mass of epithelioid cells and granulocytes, surrounded by a proliferation of fibroblasts. Intense inflammatory hyperplasia characterises the surrounding tissues which results, in extreme cases, in distortion of the ctenidial filaments and disturbance to the ciliary feeding currents.Such structures are rarely reported upon in molluscs and throw light on the processes involved in the response to injury in these animals.     

Molecular analysis of mutation at the hprt locus of Chinese hamster V79 cells induced by ethyl methanesulphonate and mitomycin C

Mutation at the hprt locus of Chinese hamster V79 cells were induced by treatment with ethyl methanesulphonate (EMS), considered primarily a point mutagen and mitomycin C (MMC), a potent clastogen. EMS gave a dose-dependent induction of mutants while MMC induced a poor mutagenic response. Mutations were analysed using Southern and Northern blotting.Analysis of 9 EMS-induced and 4 spontaneous mutants yielded no detectable alterations in the hprt locus after digestion of DNA with 6 restriction enzymes. Mutants without detectable changes carried presumptive point mutations. In contrast, 4 out of 12 MMC-induced mutants had detectable alterations. 2 of these appeared to have lost the entire hprt gene while the other 2had prodable partial deletions. For these 4 deletion mutants no hprt mRNA was detected. 3 MMC-induced and 1 EMS-induced mutants had reduced levels of hprt mRNA. All the other mutants showed normal levels of hprt mRNA and the message detected was always of the correct size.It is suggested that the poor mutagenic response induced by MMC may be due to the lethal nature of large deletions involving both the hemizygous hprt locus and adjacent essential genes. This may lead to an underestimate of the mutagenicity of clastogenic agents such as MMC in the V79 HPRT mutation assay.     

Ileal mucosal mast cell, eosinophil, and goblet cell populations during Hymenolepis diminuta infection of the rat.

The population dynamics in the enteric connective tissues of eosinophils, mucosal mast cells (MMC), and in the mucosal epithelium of goblet cells were examined morphometrically in fixed ileal tissue of outbred Sprague Dawley rats during the first 32 days of infection with the tapeworm Hymenolepis diminuta. MMC and eosinophils were present in the lamina propria and submucosa; however, only eosinophils were also present in the muscularis externa. Eosinophilic infiltrate was first observed in the lamina propria at 15 days postinfection (dpi) and the numbers of eosinophils remained elevated through 32 dpi. Initial mucosal mastocytosis was detected on 6 dpi and MMC numbers continued to rise over the study period without reaching a plateau. Goblet cell hyperplasia occurred only at 32 dpi. In contrast to some intestinal nematode infections where these same 3 cell types are associated with the host's expulsion responses, H. diminuta is not lost by a rapid host response in the outbred Sprague Dawley rat strain used in these experiments. We suggest that either the induction of hyperplasia of these host effector cells in ileum tissue during H. diminuta infection is not capable of triggering parasite rejection mechanisms, or the function of the induced hyperplasia is necessary for some as yet unassociated physiological or tissue architecture change in the host's intestine.     

YopP-Expressing Variant of Y. pestis Activates a Potent Innate Immune Response Affording Cross-Protection against Yersiniosis and Tularemia

Plague, initiated by Yersinia pestis infection, is a rapidly progressing disease with a high mortality rate if not quickly treated. The existence of antibiotic-resistant Y. pestis strains emphasizes the need for the development of novel countermeasures against plague. We previously reported the generation of a recombinant Y. pestis strain (Kim53ΔJ+P) that over-expresses Y. enterocolitica YopP. When this strain was administered subcutaneously to mice, it elicited a fast and effective protective immune response in models of bubonic, pneumonic and septicemic plague. In the present study, we further characterized the immune response induced by the Kim53ΔJ+P recombinant strain. Using a panel of mouse strains defective in specific immune functions, we observed the induction of a prompt protective innate immune response that was interferon-γ dependent. Moreover, inoculation of mice with Y. pestis Kim53ΔJ+P elicited a rapid protective response against secondary infection by other bacterial pathogens, including the enteropathogen Y. enterocolitica and the respiratory pathogen Francisella tularensis. Thus, the development of new therapies to enhance the innate immune response may provide an initial critical delay in disease progression following the exposure to highly virulent bacterial pathogens, extending the time window for successful treatment.     

The immune response of cattle to Babesia bovis (syn. B. argentina). Studies on the nature and specificity of protection.

Studies of the immune response to Babesia bovis (syn. B. argentina) in Bos taurus cattle, using the passive transfer of serum from immune animals, indicated that an effector mechanism was mediated by antibodies which reacted with the parasitized erythrocytes. During removal from the peripheral blood, the parasites did not show reduced viability on subinoculation into other non-infected animals, and thus were not dead or irreversibly damaged at this time. It was concluded that opsonization of infected erythrocytes was probably the basis of protection by the system. There was some evidence that minor variation of the protective antigen(s) occurred within strains of the parasite but this had little effect on the efficiency of the host's immune response. However, there was no cross-protection between the antibodies against different strains. These interstrain differences in antibody specificity were reconciled with earlier observations that cross-immunity commonly occurs between different strains in infected animals. It was concluded that the mechanism of cross-immunity relied on priming of the host's immune system by the protective antigen(s) of the strain so that a secondary response against the heterologous strain occurred soon after challenge.     

Bill colour and immunocompetence in the European blackbird

The level of expression of secondary sexual characters has been suggested to signal male ability to resist parasitic infestations. To test this idea, several studies have examined the link between sexual signals and immunocompetence in birds. However, most of them have used only a single aspect of immune response to evaluate immunocompetence. We investigated the relation between bill colour and immunocompetence in captive male European blackbirds, Turdus merula, during the breeding season by assessing both cell-mediated and humoral components of the immune system. The blackbird is a sexually dimorphic species with bill colour varying from yellow to orange in males. Humoral immunity was assessed by measuring both primary and secondary responses to sheep red blood cell inoculation. Cell-mediated immunity was estimated with a delayed cutaneous hypersensitivity response to an injection of a mitogen (phytohaemagglutinin). No relation was found between male bill colour and the primary humoral response. However, males with orange bills showed a lower secondary humoral response but a higher cell-mediated immune response than males with yellow bills. Thus, the relation between immunocompetence and a secondary sexual trait may differ markedly depending on which component of the immune system is under consideration. We discuss our results in relation to mechanisms involved in sexual selection. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour      

A Shift from Cellular to Humoral Responses Contributes to Innate Immune Memory in the Vector Snail Biomphalaria glabrata

Discoveries made over the past ten years have provided evidence that invertebrate antiparasitic responses may be primed in a sustainable manner, leading to the failure of a secondary encounter with the same pathogen. This phenomenon called “immune priming” or "innate immune memory" was mainly phenomenological. The demonstration of this process remains to be obtained and the underlying mechanisms remain to be discovered and exhaustively tested with rigorous functional and molecular methods, to eliminate all alternative explanations. In order to achieve this ambitious aim, the present study focuses on the Lophotrochozoan snail, Biomphalaria glabrata, in which innate immune memory was recently reported. We provide herein the first evidence that a shift from a cellular immune response (encapsulation) to a humoral immune response (biomphalysin) occurs during the development of innate memory. The molecular characterisation of this process in Biomphalaria/Schistosoma system was undertaken to reconcile mechanisms with phenomena, opening the way to a better comprehension of innate immune memory in invertebrates. This prompted us to revisit the artificial dichotomy between innate and memory immunity in invertebrate systems.     

Macrophage-mediated cytolysis of erythrocytes in the guinea pig. II. Role of oxidative burst products in macrophage cytotoxicity activated by lectins and phorbol ester derivatives

Guinea pig peritoneal macrophages (GPPM) exhibited enhanced production of O₂^? and H₂O₂, and cytolytic activity toward erythrocytes, in response to reagents such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA), its methylated derivative 4-O-MeTPA, Con A, wheat germ agglutinin (WGA), and opsonized zymosan. In order to examine the possible role of oxidative burst products such as O₂^? and H₂O₂ in the cytolytic process, we used reagents and enzymes which influence the balance of O₂^? and H₂O₂ outside and inside the GPPM cells. Macrophage-mediated cytolysis (MMC) of erythrocytes in the presence of the activators and modulators was assessed by ⁵¹Cr release assay. MMC activated by TPA and 4-O-MeTPA was inhibited by scavengers of H₂O₂ such as catalase and α-tocopherol, and was augmented by the catalase inhibitor 3-amino-1,2,4-triazole, and by horseradish peroxidase. TPA- and 4-O-MeTPA-activated MMC was only partially inhibited by the O₂^? scavenger cytochrome c and the enzyme superoxide dismutase and unaffected by cytochalasin D (an inhibitor of phagocytosis). MMC activated by the lectins Con A and WGA was unaffected by the scavengers and enzymes used, but markedly inhibited by cytochalasin D. Activation of MMC by TPA, WGA, and phagocytosis of opsonized zymosan, as well as O₂^? and H₂O₂ generation triggered by these reagents, were markedly inhibited by chlorpromazine. The results indicate that GPPM-mediated cytolysis activated by lectins, phorbol ester derivatives, and phagocytosis of opsonized zymosan, is dependent on the generation of oxidative burst products, mainly H₂O₂. TPA- or 4-O-MeTPA-activated MMC is mainly an extracellular event, while lectin-activated MMC may take place within the macrophages.     

Juvenile Cell-Mediated Immune Response is Negatively Correlated with Subsequent Adult Ornament Size in Quail

Studies of the relationship between sexual traits and immune function have been at the forefront of sexual selection during the last decade. Whereas evidence is accumulating that there is a trade-off between sexual ornamentation and immunocompetence, the reasons for this trade-off are still unknown. Importantly, most studies have addressed this issue only at the adult stage, when sexual ornamentation and immune function may be fully developed. We show here that juvenile cell-mediated immune response is negatively correlated with subsequent size of an adult sexual ornament in the Chinese quail, Coturnix chinensis. This suggests that the cost of development of a functional immune system is traded off against secondary sexual traits, and that costs of high immunocompetence in juveniles may not be manifested until sexual maturity. Ontogenetic studies of the development of the immune function and associated costs and trade-offs are likely to provide a more complete picture of the links between sexual selection and immunobiology.     

Macrophage-mediated cytolysis off erythrocytes in the guinea pig. I. Activation by stimulators of the oxidative burst

Oxygen metabolites generated by macrophages may exert membrane injury to various cells. In this study reagents, which induce superoxide (O₂^?) and hydrogen peroxide (H₂O₂) production by paraffin oil elicited adherence purified guinea pig peritoneal macrophages (GPPM), were studied as to their potential to activate macrophage-mediated cytolysis (MMC) against allogeneic and autologous erythrocytes. Strong MMC reactions were activated by 12-O-tetra-decanoylphorbol-13-acetate (TPA), methylated TPA (4-O-MeTPA), opsonized zymosan, and out of six lectins tested, by wheat germ agglutinin (WGA) and concanavalin A (Con A). The cGMP elevators: sodium nitroprusside and sodium azide and the formyl-methionyl-type chemotactic peptides were ineffective. MMC activated by TPA, 4-O-MeTPA, WGA, and Con A was unaffected by colchicine and partially inhibited by cytochalasin B. TPA-activated MMC was abolished by diethyldithiocarbamate (DDC) (inhibitor of superoxide dismutase) and catalase, while WGA and Con A-activated MMC were only partially inhibited by DDC and unaffected by catalase.     

Serotonergic Chemosensory Neurons Modify the C. elegans Immune Response by Regulating G-Protein Signaling in Epithelial Cells

The nervous and immune systems influence each other, allowing animals to rapidly protect themselves from changes in their internal and external environment. However, the complex nature of these systems in mammals makes it difficult to determine how neuronal signaling influences the immune response. Here we show that serotonin, synthesized in Caenorhabditis elegans chemosensory neurons, modulates the immune response. Serotonin released from these cells acts, directly or indirectly, to regulate G-protein signaling in epithelial cells. Signaling in these cells is required for the immune response to infection by the natural pathogen Microbacterium nematophilum. Here we show that serotonin signaling suppresses the innate immune response and limits the rate of pathogen clearance. We show that C. elegans uses classical neurotransmitters to alter the immune response. Serotonin released from sensory neurons may function to modify the immune system in response to changes in the animal''s external environment such as the availability, or quality, of food.     

Mechanism and specificity of macrophage-mediated cytotoxity.

The cytotoxic effect of macrophages derived from alloimmunized mice (immune macrophages) was found to be immunologically specific. The immune macrophages killed only target macrophages carrying the alloantigens used for immunization in mixed macrophage cultures (MMC) under optimal conditions of contact between effector and target cells. T-sensitized lymphocytes, but not B cells, were capable of arming nonimmune macrophages and conferring upon them cytotoxic activity; the arming factor, which seemed to be a T mediator or T-cell receptor (membrane component) was removable by trypsin. Frequent rinsing or addition of hydrocortisone significantly decreased the cytotoxicity of the MMC. Pretreatment of peritoneal cells with anti-θ antisera and complement markedly decreased immune macrophage cytotoxic activity. It is suggested that the presence of a very small number of T-sensitized lymphocytes is required for strong cytotoxic activity to be manifested by the macrophages.     

Adaptive Immunity Alters Distinct Host Feeding Pathways during Nematode Induced Inflammation,a Novel Mechanism in Parasite Expulsion

Gastrointestinal infection is often associated with hypophagia and weight loss; however, the precise mechanisms governing these responses remain poorly defined. Furthermore, the possibility that alterations in feeding during infection may be beneficial to the host requires further study. We used the nematode Trichinella spiralis, which transiently inhabits the small intestine before migrating to skeletal muscle, as a biphasic model of infection to determine the cellular and molecular pathways controlling feeding during enteric and peripheral inflammation. Through the infection of genetically modified mice lacking cholecystokinin, Tumor necrosis factor α receptors and T and B-cells, we observed a biphasic hypophagic response to infection resulting from two separate immune-driven mechanisms. The enteroendocrine I-cell derived hormone cholecystokinin is an essential mediator of initial hypophagia and is induced by CD4+ T-cells during enteritis. In contrast, the second hypophagic response is extra-intestinal and due to the anorectic effects of TNFα during peripheral infection of the muscle. Moreover, via maintaining naive levels of the adipose secreted hormone leptin throughout infection we demonstrate a novel feedback loop in the immunoendocrine axis. Immune driven I-cell hyperplasia and resultant weight loss leads to a reduction in the inflammatory adipokine leptin, which in turn heightens protective immunity during infection. These results characterize specific immune mediated mechanisms which reduce feeding during intestinal or peripheral inflammation. Importantly, the molecular mediators of each phase are entirely separate. The data also introduce the first evidence that I-cell hyperplasia is an adaptively driven immune response that directly impinges on the outcome to infection.     

Coexpression of RTI40 with alveolar epithelial type II cell proteins in lungs following injury: identification of alveolar intermediate cell types

Injured alveolar epithelial type (AT) I cells are replaced following the proliferation and transformation of ATII cells to new ATI cells. RTI(40) is an ATI cell-specific protein required for normal lung development. We hypothesized that intermediate cell types in the ATII-to-ATI cell transformation would coexpress RTI(40) and ATII cell-selective proteins. To test this hypothesis, we used a rat model of Staphylococcus aureus-induced acute lung injury and a panel of ATI and ATII cell-specific and -selective antibodies. S. aureus induced an acute inflammatory reaction that was resolving by day 3 postinoculation. At day 3 postinoculation, the alveolar wall was thickened secondary to ATII cell hyperplasia. With the use of confocal microscopy, there was a fivefold increase in the fractional surface area of alveolar walls stained with ATII cell membrane proteins (RTII(70) and MMC4) and a decrease in the fractional surface area associated with RTI(40)-expressing cells. S. aureus-treated lungs also contained unique cell types that coexpressed the RTI(40) and ATII markers RTI(40)/MMC4/RTII(70)- and RTI(40)/MMC4-positive cells. These cells were not observed in control lungs. RTI(40)/MMC4-positive cells were also found in cultured ATII cells before they transformed to an ATI-like phenotype. Our data suggest that RTI(40)/MMC4/RTII(70)- and RTI(40)/MMC4-positive cells are intermediates in the ATII-to-ATI cell transformation. These data also suggest that the coexpression of RTI(40) with ATII cell proteins may be used to identify and investigate ATII cell transdifferentiation to ATI cells following injury.