Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The response of spleen and peripheral blood lymphocytes (PBL) to mitogen stimulation with phytohemagglutinin (PHA), Concanavalin A (ConA), and pokeweed mitogen (PWM) was determined for owl monkeys (Aotus trivirgatus) experimentally infected with the Vietnam-Oak Knoll (FVO) and the Uganda-Palo Alto (FUP) strains of Plasmodium falciparum. PBL from Panamanian Aotus monkeys with less than 25% FVO infection responded normally to mitogen stimulation; however, increased parasitemia of 25--50% resulted in a significant suppression of ConA responsiveness. Colombian Aotus monkeys infected with the PUF strain also developed a suppression to ConA stimulation but with a lower parasitemia (10--25%). When the parasitemia became greater than 50% in these animals, PHA, ConA, and PWM responses were significantly decreased in cultures of PBL. Spleen cells from all acutely infected Aotus monkeys were suppressed to PHA and ConA, but not PWM stimulation. Changes in mitogen responsiveness of experimentally infected Aotus monkeys are similar to those reported for humans with acute falciparum malaria.
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PMID:Effect of falciparum malaria infection on the in vitro mitogen responses of spleen and peripheral blood lymphocytes from owl monkeys. 9 58

Spleen macrophages from Plasmodium berghei-infected mice are more efficient in the ingestion of parasitized reticulocytes than spleen macrophages obtained from normal animals. Other indications of spleen macrophage activation detected during malarial infection are enhanced macrophage spreading and increased phagocytosis of opsonized and nonopsonized sheep erythrocytes (E). Peritoneal macrophages are not activated to a significant degree. The appearance of antibodies directed against Forssman antigen, but not to other erythrocyte antigens, is also a feature of this infection and explains the ingestion of unsensitized E by spleen macrophages of the diseased animals. The recognition and ingestion of parasitized reticulocytes by infected mice in mediated by cold-agglutinin type immunoglobulins that appear during P. berghei infection and can be blocked by the Fc-binding protein A from Staphylococcus aureus. In advanced stages of the disease, the serum of infected animals inhibits phagocytosis, probably because of the high level of circulating immune complexes. Thus, the clearance of malaria parasites is regulated by several elements of the immune system, in addition to levels of specific antimerozoite antibodies, including the amount of antibodies bound to reticulocytes, the presence of circulating immune complexes, and the degree of macrophage stimulation.
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PMID:Immune phagocytosis in murine malaria. 44 88

In order to study the kinetics and composition of the polyclonal B-cell activation associated to malaria infection, antigen-specific and non-specific B-cell responses were evaluated in the spleens of mice infected with Plasmodium yoelii 17XL or injected with lysed erythrocytes or plasma from P. yoelii infected mice or with P. falciparum culture supernatants. Spleen/body weight ratio, numbers of nucleated spleen cells and Immunoglobulin-containing and Immunoglobulin-secreting cells increased progressively during the course of infection, in parallel to the parasitaemia. A different pattern of kinetics was observed when anti-sheep red blood cell and anti-trinitrophenylated-sheep red blood cell plaque forming cells response were studied: maximum values were observed at early stages of infection, whereas the number of total Immunoglobulin-containing and Immunoglobulin-secreting cells were not yet altered. Conversely, at the end of infection, when these latter values reached their maximum, the anti-sheep red blood cell and anti-trinitrophenylated-sheep red blood cell specific responses were normal or even infranormal. In mice injected with Plasmodium-derived material, a higher increase in antigen-specific PFC was observed, as compared to the increase of Immunoglobulin-containing and Immunoglobulin-secreting cell numbers. This suggested a "preferential" (antigen-plus mitogen-induced) stimulation of antigen-specific cells rather than a generalized non-specific (mitogen-induced) triggering of B-lymphocytes. On the basis of these and previous results, it is suggested that the polyclonal B-cell activation that takes place during the course of infection appears as a result of successive waves of antigen-specific B-cell activation.
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PMID:Kinetics of antigen specific and non-specific polyclonal B-cell responses during lethal Plasmodium yoelii malaria. 128 89

That a normal spleen can rupture spontaneously has long been a point of debate. A definitive case is reported here in an attempt to resolve the issue in its favour. Spleen involved in tropical diseases like malaria, infectious mononucleosis and typhoid fever is prone to rupture spontaneously as well as in cases follow minor trauma. In contrast, normal spleen ruptures almost always following severe trauma, such as road accidents or fall from significant heights. Though cases of spontaneous rupture of normal spleens have appeared off and on in the past, doubt has always surrounded the very existence of such an entity. We are reporting a definitive case of spontaneous rupture of normal spleen. This is only the second case of its kind since 1958 and the first ever from the Indian subcontinent.
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PMID:Spontaneous rupture of normal spleen: an enigma recalled. 141 60

This study investigates the suppressive effect of testosterone (Te) on the self-healing of Plasmodium chabaudi malaria in female mice of the strain C57BL/10, and, in particular, the possible role of spleen cells in mediating this Te effect. Our data show the following. (i) About 80% of B10 mice infected with 10(6) P. chabaudi-infected erythrocytes are capable of self-healing the infections. This capability is progressively impaired and finally abrogated after pretreating the B10 mice with Te for 3 weeks. (ii) The spleen is Te responsive. This becomes evident in a reduction of total spleen cells from 1.05 x 10(8) to 0.54 x 10(8) on average after Te treatment for 3 weeks. Moreover, Te treatment causes an increase in the relative proportion of CD8+ cells by about 4% and a decrease of Ig+ cells by about 4.5%, as revealed by flow cytometry. (iii) Spleen cells mediate the suppressive Te effect as revealed by adoptive transfer experiments. The percentage of self-healing mice dramatically decreases to about 8% when they receive, just prior to infection, nucleated spleen cells isolated from mice treated with Te for 3 weeks. This suppressive effect can be transferred by T cells in particular but also by non-T cells, though to a lesser extent. (iv) The adoptively transferred cells mediate their suppressive effect on self-healing only if the recipient mice receive Te during infection. Our data suggest that spleen cells become functionally changed by the Te treatment for 3 weeks. Particularly T cells, but also non-T cells, gain P. chabaudi-specific suppressive activities, and the cells require a Te-induced factor(s) to mediate these activities.
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PMID:Testosterone-induced abrogation of self-healing of Plasmodium chabaudi malaria in B10 mice: mediation by spleen cells. 193 7

The malaria parasite, Plasmodium yoelii 17X, causes a self-limited, nonlethal infection characterized, in the blood stage, by preferential invasion of reticulocytes. Previous studies have suggested that immunity to the blood stage infection may be related to enhanced levels of class I MHC Ag on the parasitized reticulocyte surface and can be adoptively transferred to immunodeficient mice by immune CD8+ T cells in the absence of CD4+ T cells. To further examine the mechanisms of CD8+ T cell involvement in immunity to blood stage P. yoelii infection, we performed in vivo CD8 depletion and adoptive transfer experiments. Depletion of CD8+ T cells during primary blood stage infection in BALB/c mice did not diminish the ability of the mice to resolve their infections. Spleen cells from immune BALB/c and C57BL/10 mice were transferred to BALB/c-nu/nu and C57BL/10-nu/nu mice, respectively. The recipient mice were CD4 depleted in vivo to kill any transferred CD4+ T cells. The mice failed to control the infection. Populations of CD4-, CD8+ T cells were transferred from immune CBA/CaJ donors to in vivo CD4-depleted CBA/CaJ recipients. The mice were unable to control the infection. Although immune unfractionated spleen cells transferred rapid protection in all three mouse strains and immune CD4+ T cells transferred immunity in the two mouse strains studied, CD8+ T cells by themselves were neither protective nor did they enhance immunity.
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PMID:Adoptive transfer of CD8+ T cells from immune animals does not transfer immunity to blood stage Plasmodium yoelii malaria. 196 71

The role of gamma interferon (IFN-gamma), a pluripotent lymphokine capable of activating macrophages, in acquired immunity to blood-stage malaria was investigated. C57BL-derived, lipopolysaccharide-resistant C57BL/10ScN mice, which were found to be resistant to intraperitoneal (i.p.) infection with 10(6) Plasmodium chabaudi AS parasitized erythrocytes, were treated with monoclonal anti-IFN-gamma antibody (MAb). Two MAbs were used: R4-6A2, a rat anti-mouse, neutralizing immunoglobulin G1, which was prepared against natural murine IFN-gamma, and DB-1, a murine anti-rat immunoglobulin G1 prepared against recombinant rat IFN-gamma, which can neutralize the murine molecule as well as the rat molecule. C57BL/10ScNH mice were injected i.p. with 200 micrograms of R4-6A2 1 day before infection and every 3 days through day 21. Control mice were treated with normal rat serum. In separate experiments, DB-1 (1.0 mg per week for 4 weeks) was administered i.p. to C57BL/10ScNH mice beginning on the day of infection; control mice were untreated. Control and MAb-treated mice were infected i.p. with 10(6) P. chabaudi AS parasitized erythrocytes, and the course and outcome of infection were determined. Control mice exhibited a course of infection that was characterized by a peak parasitemia between 30 and 40% parasitized erythrocytes and elimination of the parasite by 4 weeks. MAb-treated mice exhibited a significantly greater parasitemia 1 to 2 days before the peak parasitemia as well as a significantly greater peak parasitemia but also completely cleared the infection by 4 weeks. Thus, these results suggest that treatment with anti-IFN-gamma MAb impairs but does not completely abrogate host resistance to P. chabaudi AS. We also examined the kinetics of IFN-gamma production by spleen cells cultured in vitro with malaria antigen or concanavalin A. Spleen cells were recovered from individual C57BL/6 mice at various times after i.p. infection with 10(6) P. chabaudi AS parasitized erythrocytes. The amount of IFN-gamma produced was quantitated by enzyme-linked immunosorbent assay. In each case, the peak of IFN-gamma production occurred just before the peak parasitemia, followed by a decrease to little or no IFN-gamma production through 42 days postinfection. There was thus a parallel between the kinetics of production of IFN-gamma in vitro by spleen cells from infected animals and the requirement in vivo for the endogenous molecule just before and at the time of peak parasitemia. In conclusion, these results suggest that IFN-gamma-dependent and -independent mechanisms contribute to host resistance to P. chabaudi AS.
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PMID:Role of endogenous gamma interferon in host response to infection with blood-stage Plasmodium chabaudi AS. 211 42

Levels of mature lymphocytes, granulocytes, macrophages, platelets, their progenitor cells, and cytokines were monitored in the blood, marrow, and spleen during fatal or nonfatal murine malarial infections. In all four malaria models, before anemia developed, there was a lymphopenia, a rapid lymphocyte depletion in the marrow with a compensating rise in spleen lymphocytes, thrombocytopenia with increased megakaryocytic progenitor cell numbers, and monocyte increases in the bone marrow and later the spleen. The development of anemia was associated with a monocytosis and neutropenia, an increase in granulomonocytic progenitor cells in the spleen, and a reduction of spleen lymphocytes. Spleen granulocytes, monocytes, and their progenitor cells increased two- to threefold more in nonfatal than in fatal malaria and the spleen lymphocyte pool became severely depleted in fatal malaria. The data suggest that a defective effector cell response was of importance for the fatal outcome of the disease. Other than an early rise in serum macrophage colony stimulating factor levels in fatal infections, changes in levels of the regulators of these effector cells did not correlate well with the outcome of the infection.
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PMID:Changes in hemopoietic and regulator levels in mice during fatal or nonfatal malarial infections. II. Nonerythroid populations. 214 42

When mice are immunized with radiation-attenuated sporozoites they are solidly protected against sporozoite challenge by an immune response that has been shown to require CD8+ lymphocytes in several strains of mice. The target of this CD8+ T-cell-dependent immunity has not been established. Immune BALB/c mice were shown to develop malaria-specific, CD8+ T-cell-dependent inflammatory infiltrates in their livers after challenge with Plasmodium berghei sporozoites. Spleen cells from immune BALB/c and C57BL/6 mice eliminated hepatocytes infected with the liver stage of P. berghei in vitro. The activity against infected hepatocytes is not inhibited by antibodies to interferon-gamma and is not present in culture supernatants. It is genetically restricted, an indication that malaria antigens on the hepatocyte surface are recognized by immune T-effector cells. Further subunit pre-erythrocytic stage malaria vaccine development will require identification of the antigens recognized by these T cells and a method of immunization that induces such immunity.
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PMID:T lymphocytes from mice immunized with irradiated sporozoites eliminate malaria from hepatocytes. 215 Dec 70

The target of the CD8+ T cell-dependent immunity that protects mice immunized with irradiation-attenuated malaria sporozoites has not been established. Immune BALB/c mice were shown to develop malaria-specific, CD8+ T cell-dependent inflammatory infiltrates in their livers after challenge with Plasmodium berghei sporozoites. Spleen cells from immune BALB/c and C57BL/6 mice eliminated hepatocytes infected with the liver stage of P. berghei in vitro. The activity against infected hepatocytes is not inhibited by antibodies to interferon-gamma and is not present in culture supernatants. It is genetically restricted, an indication that malaria antigens on the hepatocyte surface are recognized by immune T effector cells. Subunit vaccine development will require identification of the antigens recognized by these T cells and a method of immunization that induces such immunity.
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PMID:Sporozoite vaccine induces genetically restricted T cell elimination of malaria from hepatocytes. 252 77


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