The comparative characteristics of the biological and immunomodulating activities of enzyme preparations of microbial origin]

A number of enzyme preparations of microbial origin such as immunomodulators and immunostimulators have been studied in vitro according to reactions of rosette technique of cell (ROC) active and general, adhesion, activation of a complement and also the spontaneous activity and phagocytosis of neutrophils have been determined. The enzyme preparations of microbial origin have been shown to be capable of causing immunomodulation and of influencing the specific and nonspecific immune response. Unlike the enzymes of animal origin the enzymes of microbial origin are effective in smaller concentrations. The studied preparations modulate the immune response differently according to ROC, adhesion. Each of preparations has specific features of biological activity--bacterio-stationary in reaction to a certain group of microorganisms and some specific features of reaction with cell and levels of immune reactions.     

Modulation of viral infections by cytokines.

The survival of a host challenged by viral infection depends on many factors. Some are specific, such as antiviral T-cell and B-cell responses. Others are nonspecific, such as intrinsic cellular resistance, macrophage activation, and activation of humoral protective mechanisms (e.g., complement, coagulation, etc.). Cytokines are important mediators and regulators of both types of host response. Furthermore, orchestration of specific humoral and cellular immune responses requires the participation of many cytokines. Details of the complex and overlapping roles that cytokines play in specific immune responses is beyond the scope of this review. Instead, this review will focus on the nonspecific antiviral effects of cytokines.     

Immune response and disease resistance of Oreochromis mossambicus to Aeromonas hydrophila after exposure to hexavalent chromium

The objective of this study was to investigate the effect of chronic exposure to sublethal concentrations of hexavalent chromium (K2Cr2O7) on the immune response and disease resistance of Oreochromis mossambicus (Peters) to bacterial Aeromonas hydrophila infection. Fish (45 to 50 g) were exposed to 0.005, 0.05, 0.5, and 5 mg l(-1) [0.01, 0.1, 1, and 10% LC50, respectively] of hexavalent chromium Cr (VI) for 28 d. The specific immune response was assessed by antibody response to A. hydrophila by bacterial agglutination assay, and to sheep red blood cells (SRBC) by plaque forming cell (PFC) assay. In addition, nonspecific immune mechanisms were assessed by serum lysozyme activity and reactive nitrogen intermediates, the latter in terms of nitric oxide (NO) production by peripheral blood leucocytes. Overall immunity was assessed by disease resistance against live virulent A. hydrophila. The study clearly indicated that chronic exposure of fish to 0.5 and 5 mg l(-1) of chromium (VI) decreased both nonspecific and specific parameters of the immune system, which resulted in a lower disease resistance to A. hydrophila. Interestingly, 0.05 mg l(-1) of Cr (VI) enhanced disease resistance and both nonspecific and specific immune responses to A. hydrophila. Our study revealed a concentration-dependent modulation of the immune system by chromium (VI), as demonstrated by suppressive or stimulatory effects on lymphocytes, lysozyme, phagocytic killing mechanisms, and disease resistance in O. mossambicus.     

Types of immune-inflammatory responses as a reflection of cell–cell interactions under conditions of tissue regeneration and tumor growth

Inflammatory infiltration of tumor stroma is an integral reflection of reactions that develop in response to any damage to tumor cells including immune responses to antigens or necrosis caused by vascular disorders. In this review, we use the term “immune-inflammatory response” (IIR) that allows us to give an integral assessment of the cellular composition of the tumor microenvironment. Two main types of IIRs are discussed: type 1 and 2 T-helper reactions (Th1 and Th2), as well as their inducers: immunosuppressive responses and reactions mediated by Th22 and Th17 lymphocytes and capable of modifying the main types of IIRs. Cellular and molecular manifestations of each IIR type are analyzed and their general characteristics and roles in tissue regeneration and tumor growth are presented. Since inflammatory responses in a tumor can also be initiated by innate immunity mechanisms, special attention is given to inflammation based on them. We emphasize that processes accompanying tissue regeneration are prototypes of processes underlying cancer progression, and these processes have the same cellular and molecular substrates. We focus on evidence that tumor progression is mainly contributed by processes specific for the second phase of “wound healing” that are based on the Th2-type IIR. We emphasize that the effect of various types of immune and stroma cells on tumor progression is determined by the ability of the cells and their cytokines to promote or prevent the development of Th1- or Th2-type of IIR. Finally, we supposed that the nonspecific influence on the tumor caused by the cytokine context of the Th1- or Th2-type microenvironment should play a decisive role for suppression or stimulation of tumor growth and metastasis.     

The role of cytokines in immunological tolerance: potential for therapy

Current immunosuppression protocols, although often effective, are nonspecific and therefore hazardous. Consequently, immunological tolerance that is antigen specific and does not globally depress the patient's immune system has become one of the Holy Grails of immunology. Since the discovery that cytokines have immunomodulatory effects, extensive research has investigated the potential of these molecules to induce and maintain specific immunological tolerance in the context of transplantation, allergy and autoimmunity. In this article, we review the possible mechanisms by which cytokines can modulate the immune response and the animal models that frequently confound the theory that a single cytokine, or group of cytokines, can induce tolerance in a predictable manner. Finally, we discuss the role of cytokines at a paracrine level, particularly in the context of inducing and maintaining antigen-specific, regulatory T cells with the clinical potential to suppress specific immune responses.     

Modulating effect of electric acupuncture stimulation on the bioelectrical activity of neurons of specific and nonspecific thalamic nuclei

Bioelectric reactions of individual neurons in specific and nonspecific thalamus nuclei were studied in acute experiments on cats. Auricular or body point electroacupuncture (EAP) was shown to affect the functions of spontaneously active neurons in the nuclei under study. Two types of spontaneously active neurons were identified: some were activated and some inhibited in response to EAP stimulation. The number of neurons activated in response to EAP was 50% greater in specific thalamus nuclei than in nonspecific ones, while inhibition was mostly observed in nonspecific thalamus cells.     

Interaction of intracellular proteases and immune mechanisms

Intracellular proteases play an important role both in nonspecific and specific immune reactions. Results concerning the interaction of these enzymes with phagocytic factors responsible for killing microorganisms are presented. In inflammatory foci, proteases released from destroyed leukocytes have been found to modify the function of antibodies present. They particularly reduce their complement fixation activity. Macrophages with differing proteolytic activity demonstrated diverse effects on the formation of antibodies tested by Jerne's plaque technique in young rabbits immunized with sheep erythrocytes. Whereas alveolar macrophages diminished antigen immunogenicity, peritoneal macrophages enhanced it.     

Modeling immune responses with handling time

Simple predator-prey type models have brought much insight into the dynamics of both nonspecific and antigen-specific immune responses. However, until now most attention has been focused on examining how the dynamics of interactions between the parasite and the immune system depends on the nature of the function describing the rate of activation or proliferation of immune cells in response to the parasite. In this paper we focus on the term describing the killing of the parasite by cell-mediated immune responses. This term has previously been assumed to be a simple mass-action term dependent solely on the product of the densities of the parasite and the immune cells and does not take into account a handling time (which we define as the time of interaction between an immune cell and its target, during which the immune cell cannot interact with and/or destroy additional targets). We show how the handling time (i) can be incorporated into simple models of nonspecific and specific immunity and (ii) how it affects the dynamics of both nonspecific and antigen-specific immune responses, and in particular the ability of the immune response to control the infection.     

Lymphocyte and neutrophil dysfunction associated with hepatitis B virus and hepatitis non-A, non-B virus infection in the chimpanzee.

Chimpanzees were examined for the effect of viral hepatitis infections on specific and nonspecific immune response mechanisms. The data suggest that infection with either hepatitis B virus or hepatitis non-A, non-B virus may result in suppression of cellular immune response components. Mitogen-induced lymphocyte proliferation was lower in virus-infected chimpanzees than in naive animals. Neutrophils from virus infected animals exhibited decreased or altered chemiluminescence kinetics.     

Effects of serotonin on antigen-nonspecific suppressors of the thymus

Study of nonspecific suppressors of the thymus in inhibition of immune response by serotonin is carried out in CBA mice. We have tested a selective effect of 2-deoxyguanosine on antigen nonspecific T suppressors of the thymus. In syngeneic adoptive transfer on the 3rd day after immunization it is established that antigen nonspecific immune response (rosette-forming cells) after serotonin treatment amounts to 71%, in intact animals--37%. When estimating the plague forming cells the antigen nonspecific suppressive thymocytes make up 21.9% in immune mice, 62.5% in immune mice after serotonin treatment, 29.7% in intact animals.     

Mitogenic effect of Legionella pneumophila: the ratio of proliferating T- and B-cells changes after immunization

The splenic lymphocyte proliferative response of guinea-pigs immunized with L. pneumophila antigen (ALP) was studied. The immune animals were shown to express enhanced reactivity in response to E. coli lipopolysaccharide, as compared to the controls, while the response to concanavalin A was markedly decreased. After 3 days in the culture ALP induced a significant nonspecific lymphocyte transformation that was expressed to a similar degree in both experimental and control group. However, after a 5-day incubation ALP induced a specific proliferative response of the immunized guinea-pig splenocytes. The experiments on fractionation by passing through the column with nylon wool revealed that T cells are activated in non-immunized guinea-pigs. The results obtained prove that T cells mediate the immune response to ALP in guinea-pigs.     

A differential effect of IgM and IgG antibodies on the blastogenic response of lymphocytes to rubella virus

Peripheral blood lymphocytes of rabbits immunized with live rubella vaccine respond to rubella virus antigens in tissue culture with increased DNA synthesis as measured by incorporation of ³H-thymidine. This reaction can be inhibited by rubella antibody. A dose dependent effect was observed when antibodies in whole serum were mixed with virus prior to addition to lymphocyte cultures. When antisera were fractionated and their individual immunoglobulins tested, a paradoxical effect was obtained. Immune IgG although it was highly effective in neutralizing the virus was incapable of inhibiting the lymphocyte response and at times caused an increased response. In contrast, immune IgM which was less efficient in neutralizing virus caused significant suppression of the blastogenic reaction. By themselves these results might have signified that IgG and IgM antibodies have different specificities or different binding properties with respect to viral surface antigens. However, immune complexes consisting of virus and IgM reduced response of both rubella immune and normal rabbit lymphocytes to PHA. This nonspecific inhibitory action required a specific step of antigen and IgM antibody interaction and normal IgM-virus mixtures or mixtures of anti-rubella IgM and poliovirus or influenza virus did not suppress lymphocyte response to PHA. Anti-rubella IgG complexed with rubella virus did not suppress the PHA response. The IgG function was apparently limited to neutralization of the infectivity of rubella virus whereas the major role of IgM was manifested through its suppressive effect on lymphocyte reactions.     

Plasmodium berghei: Reduction of the mouse's specific lymphoproliferative response in relation to corticosterone and pregnancy

Spleen cells from mice immune to Plasmodium berghei exhibited a significantly increased in vitro proliferative response to parasitized reticulocytes compared to spleen cells from normal mice. The specific response to malaria antigen was decreased in spleen cells from pregnant immune mice in contrast to the nonspecific response to the mitogen phytohemagglutinin. Addition of mouse serum to spleen cell cultures of immune mice depressed both the phytohemagglutinin and the specific proliferative response, whereas serum of pregnant mice exerted an even stronger inhibition than serum of nonpregnant mice. Charcoal adsorption of mouse sera for the elimination of steroid hormones removed the serum dependent immunosuppression from normal as well as pregnant serum. Corticosterone added to the spleen cell cultures depressed also the proliferative response. These findings demonstrate that the response to malaria antigen is decreased in immune mice during pregnancy. The possible effect of serum corticosterone on the depression of the immune response is discussed.     

Dynamics of change in the antibacterial activity of mouse peritoneal cells during the development of experimental influenzal infection

The method of the radiometric determination of the antibacterial activity of peritoneal cells in the process of the development of viral infection has been approved. The genetically determined specific level of the antibacterial activity of these cells in different strains of mice has been established. The development of the lethal form of experimental influenza A in mice has been shown to be accompanied by the mobilization of nonspecific protective factors, including the system of interferons and the antibacterial activity of peritoneal cells. The latter factor is, seemingly, insufficient for ensuring the necessary level of protection in the animals, whose death occurs at a shorter time than that necessary for the development of specific immune response.     

Effect of unilateral nephrectomy in mice on the level of the humoral immune response to T-independent antigen

The influence of unilateral nephrectomy on the degree of humoral immune response to T-independent (polyvinylpyrrolidone, PVP) and T-dependent (sheep red blood cells, SRBC) antigens was studied. The increase in the number in antibody-forming cells (AFC) and nonspecific immunoglobulin-forming cells (nIFC) was investigated by means of the adaptive transfer model. The lethally irradiated recipients were injected with the antigen and also the spleen cells of operated and intact donors. PVP did not induce significant alterations of antibody genesis in mice receiving spleen cells of unilaterally nephrectomized animals comparing with recipients of intact spleen cells. At the same time, the kidney operation induced the increase in the number of AFC and nIFC when the SRBC were used. Hence the activation of humoral immune response induced by kidney operation was related not to the direct activation of B-lymphocytes but to T-cells. The possible causes of this activation were analyzed. Spleen cells of operated animals enhance both specific and antigen-dependent nonspecific immune response.     

Studies of the mechanisms for the induction of in vivo tumor immunity. VI. Induction of specific and nonspecific cell-mediated immunity in tumor-bearing hosts and its correlation with transplantation tumor immunity

Studies were performed to determine the development of cell-mediated cytotoxic response at tumor site in C57BL/6 mice bearing progressively growing FBL-3 ascites leukemia. The effectors isolated from tumor ascites are found to be highly cytotoxic for leukemic target cells. The levels of cytotoxicity obtained with effectors isolated from tumor site are generally higher than those obtained with immune mice. This cytotoxicity is both specific and nonspecific. The specific cytotoxicity against tumor-associated antigen is mainly mediated by T cells and the nonspecific cytotoxicity against unrelated tumor cells is mediated largely by macrophages. The T-cell-enriched preparation did not give significant natural killer activity. When testing the ability of these effectors to produce in vivo immunity against the challenge of FBL-3, it was found that only T cells could confer the transplantation-type immunity, but the immunity was transient. The macrophage-enriched preparation isolated from tumor ascites failed to give in vivo protection. These findings indicate that in FBL-3 system, mice with progressively growing tumors are able to develop immune response against tumor cells. However, this immunity is probably interfered with by a suppressor factor(s) or suppressor cells which restrict their activity to eliminate the tumor cells effectively.     

Synthesis of [(32)P]phosphoramidate for use as a low molecular weight phosphodonor reagent

Phosphoramidate serves as a useful phosphodonor reagent in protein and peptide phosphorylation, notably in studying two-component signal transduction systems in which low molecular weight phosphodonors can substitute for the phosphodonor function of histidine protein kinases in in vitro phosphorylation studies of response regulator proteins. A convenient method for the synthesis of radiolabeled phosphoramidate has not been developed, and this has limited its broader use. Here we report the synthesis of radiolabeled ammonium hydrogen phosphoramidate [(NH(4))H(32)PO(3)NH(2)] which is achieved by activation of [(32)P]orthophosphate with ethyl isocyanate followed by aminolysis with ammonium hydroxide to form the desired phosphoramidate. The procedure is conveniently carried out in a microfuge tube and requires only two successive precipitation steps to obtain pure ammonium hydrogen phosphoramidate. Molar yields of 15-30% and specific activities of 10-20 Ci/mol are readily achieved. Phosphorylation of microgram quantities of response regulator proteins CheY, CheB, and DrrA is shown. Low level, but detectable, nonspecific phosphorylation was observed for reactions near ambient temperatures when substrate response regulators lacking the active site aspartate but containing histidine residues are used. More significant levels of nonspecific phosphorylation were observed for reactions at elevated temperatures when using a nonresponse regulator control protein (RNase A).     

Immunostimulation by poly-β hydroxybutyrate–hydroxyvalerate (PHB–HV) from Bacillus thuringiensis in Oreochromis mossambicus

The present study was designed to test the immunostimulatory efficacy of poly-β hydroxybutyrate–hydroxyvalerate (PHB–HV) extracted from Bacillus thuringiensis B.t.A102 on the immune system of Oreochromis mossambicus. Fish were fed with 0%, 1%, 3% or 5% PHB–HV supplemented feed and were bled at regular intervals of 5 days. The specific immune response was measured in terms of antibody response to sheep red blood cells, the nonspecific immune mechanisms were analysed in terms of serum lysozyme activity, total peroxidases activity and antiprotease activity. The overall functional immunity was tested by experimental challenge with live virulent Aeromonas hydrophila. The results revealed that all the doses of PHB–HV supplementation in feed were effective in stimulating both specific and nonspecific immune mechanisms. The bacterial challenge experiment showed that highest dose of 5% PHB–HV supplementation was more effective than 1% and 3% doses. The study concludes that PHB–HV can be used as a potential immunostimulant in finfish aquaculture.     

A Mathematical Model of HIV Infection: Simulating T4, T8, Macrophages,Antibody, and Virus via Specific Anti-HIV Response in the Presence of Adaptation and Tropism

A mathematical model of the host’s immune response to HIV infection is proposed. The model represents the dynamics of 13 subsets of T cells (HIV-specific and nonspecific, healthy and infected, T4 and T8 cells), infected macrophages, neutralizing antibodies, and virus. The results of simulation are in agreement with published data regarding T4 cell concentration and viral load, and exhibit the typical features of HIV infection, i.e. double viral peaks in the acute stage, sero conversion, inverted T cell ratio, establishment of set points, steady state, and decline into AIDS. This result is achieved by taking into account thymic aging, viral and infected cell stimulation of specific immune cells, background nonspecific antigens, infected cell proliferation, viral production by infected macrophages and T cells, tropism, viral, and immune adaptation. Starting from this paradigm, changes in the parameter values simulate observed differences in individual outcomes, and predict different scenarios, which can suggest new directions in therapy. In particular, large parameter changes highlight the potentially critical role of both very vigorous and extremely damped specific immune response, and of the elimination of virus release by macrophages. Finally, the time courses of virus, antibody and T cells production and removal are systematically investigated, and a comparison of T4 and T8 cell dynamics in a healthy and in a HIV infected host is offered.     

The immunological properties of the main outer membrane protein of Legionella

The immunogenic properties of Legionella outer membrane main protein (OMMP) were studied by its effect on the proliferative activity of lymphocytes in guinea pigs. Preliminary immunization with OMMP activated only the specific and nonspecific proliferation of spleen cells. After infection with Legionella, secondary immune response developed in the spleen and lungs of previously immunized animals, in contrast to intact ones, and the nonspecific proliferative activity of lymphocytes in the spleen and lungs of previously immunized animals considerably increased. These results are indicative of the fact that Legionella OMMP, similarly to other Legionella antigens and immunomodulators, may be used for the formation of protective immunity.