Role of complement in immune inactivation of Mycoplasma gallisepticum

Studies were undertaken to evaluate the role of complement in the interaction between mycoplasmas and antiserum. A suspension of the A-1 strain of Mycoplasma gallisepticum in PPLO broth was incubated at 37 C with rabbit immune serum which had been heated for 30 min at 56 C. Samples were removed from the mixture at timed intervals for 1 hr for titration of the mycoplasmas in broth. When normal guinea pig serum was included in the mixture at a final dilution of 1:40, the titer fell rapidly from 10(6) to 10(2) organisms per 0.2 ml. When the guinea pig serum was heated for 30 min at 56 C or was omitted from the mixture, the immune serum did not reduce the titer. The rate of inactivation was related to the final concentration of antiserum and to the incubation temperature. The effect of the guinea pig serum was eliminated by the addition of 0.01 m sodium ethylenediaminetetraacetate or by prior absorption with an unrelated antigen-antibody complex. It was concluded that complement-like substances play an important role in immune inactivation of M. gallisepticum.     

Role of thymus-eicosanoids in the immune response.

The present review deals with the role(s) of thymus-eicosanoids in the immune response. It reports the production of cyclooxygenase and lipoxygenase metabolites of arachidonic acid by cells of the thymus microenvironment and the role(s) of these eicosanoids in the differentiation and the maturation of immature T-cells. The possibility that these products may be involved in tolerance to self is discussed. Briefly, it is likely that cells from the monocyte-macrophage lineage which constitute a part of the thymus microenvironment could contribute to the education of immature thymocytes by both presenting self-antigens and producing eicosanoids. Tolerance to self might result from PGE2-driven apoptosis and/or LTB4-induced generation of suppressor cells.     

Role of the mannose receptor in the immune response

The mannose receptor (MR) recognizes a range of carbohydrates present on the surface and cell walls of micro-organisms. The MR is primarily expressed on macrophages and dendritic cells and is involved in MR-mediated endocytosis and phagocytosis. In addition, the MR plays a key role in host defense and provides a link between innate and adaptive immunity. Herein, we will review the role of the MR in innate host defense as well as the recent evidence for its role in the adaptive response, for both humoral and cellular immune responses.     

Role of nonsynaptic communication in regulating the immune response

The discovery of nonsynaptic communication in the 1960s and 1970s was an important milestone in investigating the function of the nervous system, and it revolutionized our view about information transmission between neurons. In addition, nonsynaptic communication has a practical importance not only within the nervous system, but in the communication between the peripheral nervous system and other organ systems. Nonsynaptic communication takes place in different immune organs, which are innervated by sympathetic nerve terminals. In addition, the function of microglia, one of the immunocompetent cell types of the brain, can also be affected by neurotransmitters released from axon varicosities. The various functions of immune cells are modulated by released neurotransmitters without any direct synaptic contact between nerve endings and targeted immune cells requiring only functional neurotransmitter receptors on immune cells. Here, we briefly overview the role of the various receptor subtypes mediating nonsynaptic modulation of the function of immunocompetent cells both in the periphery and in the central nervous system.     

Role of the immune response in atherosclerosis and acute coronary syndromes

Cardiovascular diseases represent one of the most important causes of death in the world. The underlying pathogenetic process is atherosclerosis which leads to the progressive reduction of the arterial lumen and therefore to the ischemia of the perfused organs. Atherogenesis results from the interaction between the biology of the arterial wall and the various stress stimuli present in the circulating blood. The first steps of atherogenesis occur very early, already during the fetal life. Those arterial segments that are subjected to the initiating causes (including hemodynamic stress) show altered endothelial permeability and allow the infiltration of macromolecules, like lipoproteins, in the subintimal space. At the same time, the smooth muscle cells that are subjected to the same local factors produce proteoglycans able to bind lipoproteins and to promote their oxidation. Oxidized lipoproteins induce the expression of chemokines and adhesion molecules on the luminal surface of the endothelium, which then allow the local recruitment of monocytes-macrophages and T lymphocytes. This is a local inflammatory process that, in theory, should contribute to reestablish the homeostasis of the vascular wall by promoting the elimination of injured tissue and its repair. Unfortunately, for unknown reasons, the immuno-inflammatory reaction persists and autoamplifies, the various components of the immune response finally contributing to the pathogenesis of atherosclerosis as well as of atherosclerotic complications.     

Role of sialic acids in the immune response formation in tick-borne encephalitis

The content of individual forms of sialic acids and total sialic acids in the lymphocytes of tick-borne encephalitis patients has been studied. The level of sialic acids has been found to depend on the clinical form of the disease and on the content of specific IgM and IgG to tick-borne encephalitis virus. Similar dependence has been established with respect to total sialic acids in lymphocytes.     

Role of lymphokines in immune response in respiratory viral infections

The present review deals with the analysis of lymphokine response in two main respiratory viral infections: influenza and respiratory syncytial (RS) infection. Immune response in these two diseases has great phenomenological differences. In particular, in RS infection the intensive response of macrophages and epithelial cells, accompanied mainly by the synthesis and secretion of tumor necrosis factor and interleukin 8, is observed. Due to this fact no protective immunity is formed in RS infection, in contrast to influenza. The specific features of immune and lymphokine response in RS infection make it difficult to develop protective vaccines. At the same time it is with RS infection that the development of chronic bronchopulmonary diseases is linked. The analysis of the role of lymphokine response in respiratory viral infections, particularly in influenza and RS infections, confirms the necessity of revising therapy both in the acute and subacute stages of these diseases.     

Role of proteasomes in non-specific immune response of marine annelids

We investigated functioning of proteasomes and chaperones in Arenicola marina coelomocytes in conditions of lipopolysaccharide-induced inflammation. We observed the increase of chymotrypsin-like proteasome activity in coelomocytes 1 h after induction. Amount of proteasome subunits alpha- and beta-5 types increased as well. We also detected appearance of a new form of Hsp70 chaperone in infected coelomocytes. Our results allow us to consider the changes in proteasome structure and induction of chaperones as principle mechanisms in stress adaptation and defensive reactions development in annelids.     

Role of antigen and,antibody in the regulation of the immune response

The enzyme dextranase could degrade antigenic dextran in vivo even when given 6-15 d after the antigen. Dextranase injected after the antigen suppressed the immune response when given 24 but not 48 h after the antigen, indicating that the antigen must interact with the immune system for 48 h to initiate a response. Thereafter, the B cells are independent of further antigen stimulation. To show whether antibody-mediated suppression of the immune response was determinant specific FITC-conjugated SRC were applied as immunogen and antibodies were raised both against the carrier (SRC) and the FITC hapten. When these antibodies were injected 1-3 h after the immunogen they only suppressed the immune response to the corresponding determinant. Anti-carrier antibodies usually enhanced the response to the hapten. Therefore, antibody-mediated suppression of the immune response is determinant-specific and cannot be mediated in vivo to a detectable extent by the Fc part of the antibodies.     

Role of CXCR3 in the immune response to murine gammaherpesvirus 68

The chemokine IP-10 (CXCL10) and its cellular receptor CXCR3 are upregulated in the lung during murine gammaherpesvirus 68 (MHV-68) infection. In order to determine the role of the CXCR3 chemokine receptor in the immune response to MHV-68, CXCR3-/- mice were infected with the virus. CXCR3-/- mice showed delayed clearance of replicating MHV-68 from the lungs. This correlated with delayed T-cell recruitment to the lungs and reduced cytolytic activity prior to viral clearance. Splenomegaly and the numbers of latently infected cells per spleen were transiently increased. However, CXCR3-/- mice showed normal virus-specific antibody titers and effective long-term control of MHV-68 infection.     

Role of the humoral immune response in resistance to Theiler''s virus infection.

Theiler's virus, a murine picornavirus, persists in the central nervous system of susceptible strains of mice, causing chronic inflammation and demyelination in the white matter of the spinal cord. Resistant strains, however, clear the virus and do not develop late disease. In this study, we compared the characteristics of T and B lymphocytes in C57BL/6 (resistant) and SJL/J (susceptible) mice 1 week after intracerebral infection. We detected a marked increase of the number of immunoglobulin M (IgM)-secreting cells in the spleens of C57BL/6 detected a marked increase of the number of immunoglobulin M (IgM)-secreting cells in the spleens of C57BL/6 mice (but not in those of SJL/J mice), which correlated with higher levels of serum IgM antiviral antibodies. The role of the humoral response in virus clearance and resistance was demonstrated by a marked decrease in the number of infected spinal cord cells in SJL/J mice after passive transfer of serum from infected C57BL/6 donors. The B-cell response was found to be partly T cell independent. These results suggest an important role of the early humoral immune response in resistance to Theiler's virus-induced disease.     

Role of helper T-lymphocytes in modulating the humoral immune response to cholera enterotoxin

The role of helper T-lymphocytes in the modulation of humoral immune response to sheep red blood cells with choleragen has been studied in vivo, the populations of cooperating marrow cells, formed in mice under the action of hydrocortisone being used as a model. In adoptive transfer marrow cells, taken from mice on day 12 after thymectomy and from mice previously treated with antithymocyte serum, have proved incapable of humoral immune response. Choleragen, similarly to theophylline, normalizes the humoral immune response of marrow cells in thymectomized mice, but inhibits this response in intact ones, while thymosin fraction 2 restores it again, thus abolishing the action of choleragen and theophylline. The opposite effects rendered by choleragen and theophylline on humoral immune response, depending on the hormonal status of the animals and the possibility of influencing these effects by means of thymosin fraction 2 indicate that the population of helper T-lymphocytes are selectively sensitive to changes in the concentration of intracellular cAMP. Their capacity for cooperative interaction in the immune process is regulated by thymic hormones and forms the basis of the mechanism permitting the modulation of humoral immune response with choleragen.     

Modulation of the immune response to an Aeromonas hydrophila aroA live vaccine in rainbow trout: effect of culture media on the humoral immune response and complement consumption

The Aeromonas hydrophila aroA is an attenuated strain that has been assessed as a live vaccine in rainbow trout, Oncorhynchus mykiss. In this study the effects of different culture media used to grow the strain on its survival after in vitro exposure to rainbow trout serum, and on its immunogenicity in rainbow trout were compared. Four culture media were tested: Luria broth (LB), Luria broth with 0.25% glucose, trypticase soy broth (TSB), and brain-heart infusion broth (BHIB). Bacteria grown in culture media with glucose (TSB, BHIB and LB with 0.25% glucose) showed reduced complement consumption and a lower serum susceptibility. O. mykiss vaccinated with inocula prepared with BHIB- and LB-grown aroA cells resuspended in phosphate-buffered saline (PBS) showed higher and longer-lasting serum agglutinating antibody titres than those vaccinated with TSB-grown bacteria. Thus, a direct relationship between serum resistance and immunogenicity could not be established, but BHIB and LB culture media were the most effective in increasing the immunogenicity of the A. hydrophila aroA vaccine.