muramidase and Leishmaniasis

The available evidence suggests that protective immunity to Leishmania is achieved by priming the CD4(+) Th1 response. Therefore, we utilised a reverse genetics strategy to generate influenza A viruses to deliver an immunogenic Leishmania peptide. The single, immunodominant Leishmania-specific LACK(158-173) CD4(+) peptide was engineered into the neuraminidase stalk of H1N1 and H3N2 influenza A viruses. These recombinant viruses were used to vaccinate susceptible BALB/c mice to determine whether the resultant LACK(158-173)-specific CD4(+) T cell responses protected against live L. major infection. We show that vaccination with influenza-LACK(158-173) triggers LACK(158-173)-specific Th1-biased CD4(+) T cell responses within an appropriate cytokine milieu (IFN-γ, IL-12), essential for the magnitude and quality of the Th1 response. A single intraperitoneal exposure (non-replicative route of immunisation) to recombinant influenza delivers immunogenic peptides, leading to a marked reduction (2-4 log) in parasite burden, albeit without reduction in lesion size. This correlated with increased numbers of IFN-γ-producing CD4(+) T cells in vaccinated mice compared to controls. Importantly, the subsequent prime-boost approach with a serologically distinct strain of influenza (H1N1->H3N2) expressing LACK(158-173) led to a marked reduction in both lesion size and parasite burdens in vaccination trials. This protection correlated with high levels of IFN-γ producing cells in the spleen, which were maintained for 6 weeks post-challenge indicating the longevity of this protective effector response. Thus, these experiments show that Leishmania-derived peptides delivered in the context of recombinant influenza viruses are immunogenic in vivo, and warrant investigation of similar vaccine strategies to generate parasite-specific immunity.

Topics: Animals; Antigens, Protozoan; CD4-Positive T-Lymphocytes; Cytokines; Genetic Vectors; Immunity, Cellular; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H3N2 Subtype; Interferon-gamma; Leishmania; Leishmaniasis; Leishmaniasis Vaccines; Mice; Mice, Inbred BALB C; Muramidase; Protozoan Proteins; Vaccination; Vaccines, DNA

This study was conducted to investigate the immune status of Psammomys obesus (P. obesus) most implicated as a reservoir host of zoonotic cutaneous leishmaniasis (ZCL) in the Al-Ahsa area, Saudi Arabia. Based on the presence of amastigotes in the characteristic lesions and, rodents were divided into two groups. G1 was apparently healthy 10 rodents and G2 were infected 10 ones. Reduced leukocyte count, percentage lymphocyte and lysozome activity occurred in infected rodents compared to control ones. The infection significantly reduced the macrophage phagocytic activity reflected by two fold reduction in intravascular carbon clearance compared to control rodents. The results showed that ZCL produced an immunosuppressant effects in P. obesus.

Topics: Animals; Case-Control Studies; Disease Reservoirs; Gerbillinae; Immunocompromised Host; Leishmaniasis; Leukocyte Count; Lymphocyte Count; Muramidase; Rodent Diseases; Saudi Arabia

The purpose of the present study is to investigate the status of the reticuloendothelial system (RES) phagocytic function in relation to Leishmania major infection in highly susceptible BALB/c mice. The RES phagocytosis was monitored by: intravascular clearance of carbon colloid; tissue distribution 99mTechnetium labelled sulphur colloid in RES organs; and serum lysozyme enzyme level. The kinetics of RES phagocytosis during L. major infection was also studied at 0, 3, 5, 7 and 8 weeks post-infection. The results revealed that L. major parasite significantly (p less than 0.001) inhibited macrophage phagocytic function. The maximum phagocyte depression was noticed at 7 weeks following infection. The macrophage phagocytic suppression was also associated with a reduction in liver and spleen uptake of 99mTc and decrease in serum lysozyme level.

Topics: Animals; Immune Tolerance; Kinetics; Leishmania tropica; Leishmaniasis; Macrophages; Male; Mice; Mice, Inbred BALB C; Mononuclear Phagocyte System; Muramidase; Phagocytosis

The distribution and numbers of IgG-, IgA-, IgM-, and lysozyme-positive cells were investigated by the immunoperoxidase method in paraffin-sections of 13 cases of chronic cutaneous leishmaniasis of low parasite load from Saudi Arabia. The majority of the peroxidase-positive plasma cells contained IgG, whereas the numbers of IgA+ and IgM+ plasma cells were not so numerous. Small groups of squamous epithelial cells showed immunoreactivity for IgG and IgA. Similar positive staining was observed extracellularly in the oedematous upper dermis, in the endothelial cells, and in the perivascular space. The activated macrophages showed strong and diffuse peroxidase staining for lysozyme, whereas epithelioid cells and multinucleated giant cells were negative or had finely granular and considerably weaker staining. It is suggested that humoral immunity also participates in the elimination of the parasites and an immunologically induced necrosis might be responsible for the ulceration of the skin in cutaneous leishmaniasis. It is also assumed that the lysozyme immunoreactivity can be a marker of the activation state of the macrophages.

Topics: Adolescent; Adult; Child; Child, Preschool; Chronic Disease; Female; Humans; Immunoenzyme Techniques; Immunoglobulin A; Immunoglobulin G; Immunoglobulin M; Immunoglobulins; Leishmaniasis; Macrophages; Male; Muramidase; Plasma Cells; Saudi Arabia

The relationship between the destruction of Leishmania, the recruitment of monocytes and macrophage activity in the lesions of cutaneous leishmaniasis (CL) was studied in 53 biopsies representing the phases of evolution of the infection. Lysozyme, amastigotes and their degradation products were located by their specific antibodies. A rising level of monocyte influx was found to correlate with the degradation and solubilization of antigen, a falling level with final clearance. Differences in the results supported the previous concept of macrophage activation and macrophage lysis as alternative mechanisms for the elimination of Leishmania. Macrophage activation appeared to coincide with re-phagocytosis of externalized antigenic products of different type and origin. Macrophage lysis was a fully effective mechanism only when the antigen was contained within a focalized granuloma before mass lysis. Failing this, degradation and clearance of antigen were incomplete, and residues were sequestered on the periphery of the lesion where they bound to collagen and epidermis with consequential tissue damage. Antigen was demonstrated on the surface of lightly parasitized macrophages but not heavily infected ones. Other cells bound antigen without ingesting it, a process which might allow antigen presentation though it would also favour survival of parasites within the cell.

Topics: Antigens, Protozoan; Cell Movement; Granuloma; Humans; Leishmania; Leishmaniasis; Macrophage Activation; Monocytes; Muramidase

Twenty biopsies of lesions of cutaneous leishmaniasis were classified according to the mechanism of parasite elimination, on the basis of macrophage activation (five cases) or macrophage lysis (15 cases). The immunoperoxidase technique was used to demonstrate free Leishmania antigen, immunoglobulins, complement, lysozyme, C-reactive protein, beta-lipoprotein, alpha 1-antitrypsin, alpha 2-macroglobulin, plasminogen and factor VIII, which were quantitated and comparatively assessed. The fall in the parasite load during the course of the infection was associated with rising levels of IgG, IgM and IgE, and of the complement components of the classical pathway. Macrophage lysis supervened when there was an approximate equivalence of antigen and antibody, and was associated with the deposition of immune complex components. Lysis of the acute focal type (C response) was accompanied by a massive liberation of free Leishmania antigen, followed by a fall indicative of parasite elimination. The lysis of small numbers of macrophages scattered diffusely in the lesion, which was slow to reach completion (B response), was less effective and immunologically closer to the non-lytic (A) response. A terminal fall of the immunological factors other than the globulins, suggestive of resolution, was observed mainly in the C response. Lymphocytes may be important in macrophage activation associated with the macrophage A response and in the later stage of the B and C responses. However immunologically induced host-cell lysis is more important than macrophage activation for the elimination of Leishmania in the acute stage of most skin lesions. It is associated with, and may be caused by, the formation in situ of immune complexes of Leishmania antigen and antibody at an appropriate ratio.

Topics: Antigen-Antibody Complex; Antigens; Complement System Proteins; Humans; Immunoenzyme Techniques; Immunoglobulins; Leishmania; Leishmaniasis; Muramidase; Necrosis; Skin

Leishmania organisms are obligate intracellular parasites of mammalian mononuclear phagocytes in vivo. In order to study the interactions of these parasites and mononuclear phagocytes, we have used a model of infection of Leishmania major in human monocytes in vitro. The presence of intracellular parasites did not alter the normal secretion of lysozyme or result in increased secretion of prostaglandin E2 (PGE2) or superoxide anion by the monocytes. Addition of concanavalin A (Con A), which binds to a specific membrane receptor, zymosan particles or endotoxin to infected monocyte monolayers, resulted in the expected increase in PGE2 secretion. In addition, the production of superoxide by infected monocytes treated with phorbol myristate acetate was not different from control uninfected cultures. Despite this evidence of biochemical activation, neither endotoxin, zymosan nor Con A had any parasiticidal effect on the intracellular parasites. In contrast, Con A-induced lymphokines from human mononuclear cells resulted in an increased killing of the intracellular amastigotes. These studies have shown that the induction of leishmaniacidal capacity of human monocytes is dependent on the type of stimulus used to induce activation.

Topics: Cells, Cultured; Concanavalin A; Dinoprostone; Endotoxins; Humans; Leishmania; Leishmaniasis; Lymphokines; Macrophage Activation; Monocytes; Muramidase; Prostaglandins E; Zymosan

Topics: Animals; Cell Membrane; Humans; Leishmaniasis; Macrophage Activation; Macrophages; Muramidase; Oxygen; Phagocytosis; Pulmonary Alveoli; Respiration

European green lizards, Lacerta viridis, produced relatively thermostable, dithiothreitol-sensitive, non-precipitating, agglutinins and complement-fixing antibodies (CFA) to Leishmania agamae administered subcutaneously (SC), intraperitoneally (IP) or orally (OR). Antibodies were also detected by the immobilization test (IMM) and by enzyme-linked immunosorbent assay (ELISA). The most sensitive method for the detection of stimulated immunoglobulins was ELISA. Antibodies were detected as early as 3 days post-infection with ELISA and between 5 and 7 for CFA, direct agglutination (DA) and indirect haemagglutination (IHA). In the case of IMM, the times of first detection varied from 14 to 28 days. Maximum CFA (2(-8)), DA (2(-8)), IHA (2(-11)) and ELISA (2(-16)) titres were reached from 42 to 49 days with significantly higher values occurring in the OR and IP groups. With IMM, maxima occurred after 5 or 6 weeks. Following exposure, two- to five-fold significant increases in serum lysozyme levels were demonstrated but the concentrations in sera following SC, IP or OR routes of antigen administration were not significantly different when the groups were compared with each other. The highest lysozyme values (approximately 12.3 - 12.5 micrograms ml(-1)) were found in the SC and OR groups when compared to the IP (7.40 micrograms ml(-1)).

Topics: Agglutinins; Animals; Antibodies; Complement Fixation Tests; Dithiothreitol; Enzyme-Linked Immunosorbent Assay; Hot Temperature; Leishmania; Leishmaniasis; Lizards; Muramidase; Precipitins