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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The performance of an antigen of L. major-like promastigotes for the serological diagnosis of mucocutaneous leishmaniasis in the IgG-immunofluorescent test was compared to that of an antigen of L.braziliensis braziliensis. Each antigen was used to test two hundred and twenty-four sera of etiologies such as mucocutaneous leishmaniasis, deep mycoses, toxoplasmosis, malaria. Chagas' disease, visceral leishmaniasis, anti-nuclear factor, schistosomiasis, rheumatoid factor and normal controls. Agreement between responses to each antigen was high: 77.2% of leishmaniases sera agreed on a positive or a negative result to both antigens and 91.1% of control sera. Cross reactivity was restricted to Chagas' disease sera, visceral leishmaniasis, anti-nuclear factor and paracoccidioidomycosis. The quantitative response of leishmaniasis and Chagas' disease sera to both antigens was evaluated by a linear regression; although the y-intercept and the slope were different for each antigen, neither was better than the other in the disclosure of anti-Leishmania antibodies. In the case of Chagas' disease sera the L.major-like antigen was better than L.b.braziliensis' to disclose cross-reacting antibodies.
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PMID:Comparison on the performance of Leishmania major-like and Leishmania braziliensis braziliensis as antigen for New World leishmaniasis IgG-immunofluorescence test. 184 82

Monoclonal IgM rheumatoid factor-like anti-globulins were produced by in vitro stimulation of naive BALB/c spleen cells with lipopolysaccharide, and by hyperimmunization of mice with merozoites of Plasmodium falciparum, followed by fusion of the spleen cells to mouse myelomas. In vitro, these anti-globulins augmented the inhibitory effects of P. falciparum-specific polyclonal mouse sera and monoclonal IgG1 and IgG2b antibodies by binding to Fc fragments of IgG molecules attached to blood-stage parasites. In some instances, the presence of anti-globulins correlated with an increase in the number of schizonts which failed to disperse merozoites. In other cases, parasitaemia remained low in the absence of the schizont inhibition phenomenon, suggesting that anti-globulins contribute to host cell protection not only by agglutinating merozoites, but also by increasing the density of the antibody coat surrounding the parasites, thus interfering with parasite receptor-erythrocyte ligand interactions. The anti-globulins were not inhibitory when added to parasite cultures containing IgG not specific for P. falciparum. These results may help explain the function of IgM anti-globulins found at elevated serum levels in some patients with malaria or other chronic infectious diseases.
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PMID:Monoclonal IgM rheumatoid factor-like anti-globulins enhance the inhibitory effects of Plasmodium falciparum-specific monoclonal antibodies in vitro. 226 12

In a study of connective tissue and infectious disease sera, we have demonstrated IgM and IgG anti-cardiolipin activity, in a solid phase radioimmunoassay, in systemic lupus erythematosus (SLE), rheumatoid arthritis, syphilis and in acute malaria caused by four different species of Plasmodium. The highest values were noted in SLE (IgM anti-cardiolipin P less than 0.005, IgG anti-cardiolipin P less than 0.01), but there was no correlation with anti-dsDNA, rheumatoid factor or VDRL titres in any disease group. Anti-cardiolipin binding was significantly associated with the lupus anticoagulant, thrombocytopenia, spontaneous abortions and thromboses in the SLE patients. Ten SLE sera from this thrombotic subset and 10 syphilitic sera with similar anti-cardiolipin activity, were tested against four phospholipid antigens and showed significantly different anti-phosphatidyl ethanolamine/anti-phosphatidyl serine binding ratios (P less than 0.001). These differences in phospholipid epitope specificity could explain the specificity of the VDRL antigen in syphilis serology, and we discuss a putative role for anti-phosphatidyl serine in the thrombotic diathesis of SLE.
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PMID:Anti-phospholipid antibodies in syphilis and a thrombotic subset of SLE: distinct profiles of epitope specificity. 257 56

Serum from 98 Thai adults infected with Plasmodium falciparum were examined for the presence of autoantibodies. Malarial containing antibodies sera were also revealed positive for anti-nuclear antibodies with fluorescence speckled pattern, anti-smooth muscle antibodies, anti-mitochondria antibodies and rheumatoid factor. There was no detectable antibody to double stranded DNA. There was a significant relationship between high titre of malarial antibody and high frequency of speckled pattern of anti-nuclear factor or anti-nuclear antibodies. By the ELISA technique determination of serum antibodies against an extractable nuclear antigen (ENA) in patients with P. falciparum infection gave 43.8% (43 of 98) positive result. In addition, sera contained malarial antibodies gave positive antibodies to ENA in 50% (49 of 98) by tanned red cell haemagglutination. Among the positive sera with antibodies to ENA, they showed the presence of antibodies to both ribonucleoprotein RNAase sensitive (RNP) and ribonucleoprotein RNAase resistance (Sm). Also both of antibodies exhibited positive staining of speckled pattern of antinuclear factor. This observation indicated that malaria infection induces autoantibodies which were predominantly anti-nuclear antibodies.
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PMID:Autoantibodies in sera of Thai patients with Plasmodium falciparum infection. 638 70

Supernatants from Plasmodium falciparum cultures containing soluble parasite material were mitogenic for normal human peripheral blood mononuclear cells (MNC) in vitro. This was evidenced by blast transformation and significant incorporation of 3H-thymidine and confirms earlier reports of the mitogenic potential of malaria parasites. Lymphocyte activation by these malaria derived products was polyclonal as demonstrated by increased secretion of IgA, IgG and IgM by the stimulated cells. Using rat tissues and Hep-2 cells as substrates, autoantibody activity was found in the IgM fraction of the secreted immunoglobulin. Speckled anti-nuclear (ANA) antibody, anti-globulins (rheumatoid factor) and anti-intermediate filament antibodies were produced by the stimulated lymphocytes. No significant immunoglobulin secretion with autoantibody specificity was found in control cultures in which normal MNC were incubated with supernatants from non-parasitized red cell cultures. The data supports the suggestion that polyclonal lymphocyte activation by parasite derived products occurs in vivo and, in addition, provides an explanation for the presence of autoantibodies in the serum of malaria patients.
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PMID:Stimulation of autoantibody production in normal blood lymphocytes by malaria culture supernatants. 639 Mar 2

Rheumatoid factor is of limited value in the diagnosis of rheumatoid arthritis (RA) in West Africa. Consequent upon previous findings, we have studied the role of the absence of antibodies to malaria and human immunodeficiency virus (HIV) as well as the presence of the hepatitis B surface antigen (HBsAg) as diagnostic markers of rheumatoid arthritis in West Africa. We have found a significant association (p < 0.001) between RA and titre of HBsAg, but only between RA and malaria (p < 0.05) when sera with low malaria antibodies were studied. No correlation between either HBsAg or malaria and rheumatoid factor was found and no RA patient was either HIV-1 or HIV-2 positive.
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PMID:The absence of antibodies to malaria and human immunodeficiency virus, and the presence of hepatitis B surface antigen as diagnostic markers of rheumatoid arthritis. 812 6

MRL-lpr/lpr mice spontaneously develop an autoimmune disease resembling systemic lupus erythematosus and rheumatoid arthritis. One of the unique serological abnormalities in this strain is remarkably high concentrations of cryoglobulins. Analysis of immunoglobulin components in their cryoglobulins has shown selective enrichment of a particular IgG subclass, IgG3. As IgG3 enrichment is also found in two other cryoglobulins, which are induced after injection with bacterial lipopolysaccharides or infection with malaria, IgG3 apparently represents a major source of murine cryoglobulins. Studies on murine IgG3 monoclonal antibodies (mAbs) have clearly shown that murine IgG3 have the unique physiochemical property to self associate through non-specific IgG3 Fc-Fc interaction, and that most of them can generate monoclonal cryoglobulins. Most strikingly, IgG3 monoclonal cryoglobulins with rheumatoid factor (RF) activity induce extensive pathological manifestations: skin vascular purpura and glomerulonephritis with 'wire loop' lesions. Although the cryoglobulin activity of IgG3 RF mAb is solely responsible for the generation of glomerular lesions (both RF and cryoglobulin activities are necessary for skin vascular lesions), the absence of nephritogenic activity by some IgG3 cryoglobulins supports the idea that qualitative features of cryoglobulins are critical to determine their pathogenic activity. The demonstration of a positive correlation between the production of IgG3 cryoglobulins and the development of lupus nephritis in MRL-lpr/lpr mice further substantiates the pathological importance of cryogenic autoantibodies. On the other hand, it should be emphasised that non-cryogenerating IgG3 autoantibodies may not be harmful, but even protective, as a result of their interaction with pathogenic IgG3 cryoglobulins. Finally, the development of an experimental model of cryoglobulinaemia associated with vascular and glomerular disease certainly represents an invaluable opportunity to study the molecular mechanisms responsible for the generation of cryoglobulins and their associated tissue lesions, and also to assess various therapeutic approaches. Our demonstration that anti-idiotypic mAb can prevent the pathogenic effects of the cryoprecipitable IgG3 RF mAb suggests strongly that such a therapeutic approach might be successful in similar diseases in man.
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PMID:IgG3 cryoglobulins in autoimmune MRL-lpr/lpr mice: immunopathogenesis, therapeutic approaches and relevance to similar human diseases. 848 Oct 59

The immunological specificites of two human rheumatoid factor-reactive IgG monoclonal antibodies derived from unstimulated rheumatoid synovial lymphocytes have been analysed. A malaria antigen-reactive IgG monoclonal antibody from an immune donor served as a control. Purified IgG monoclonal antibody from one IgG-RF hybridoma (L1), but not from the other IgG-RF hybridoma (D1) or the anti-malaria monoclonal antibody, exhibited dose-dependent binding to multiple self and non-self antigens such as ds-DNA, cytochrome-c, bovine thyroglobulin, transferrin, cellulose and lipopolysaccharide and therefore was considered polyreactive. The immunological specificity was confirmed by inhibition experiments using the same soluble antigens as inhibitors. The polyreactivity of the IgG-RF MoAb was markedly inhibited by absorption with glycoproteins such as thyroglobulin, a commonly used target for xenoreactive natural antibodies, and cytochrome-c, indicating that the monoclonal antibody is reactive with epitopes expressed on these ligands. Since some naturally occurring antibodies are carbohydrate specific, the authors tested the IgG-RF MoAb for possible carbohydrate specificity. Absorption with certain polysaccharides containing only one or two different sugar moieties did not inhibit the binding reactivities to any of the tested antigens. Polyreactivity of the monoclonal antibody, unlike most xenoreactive natural antibodies, was not caused by reactivity with (gal alpha 1-3gal) as indicated by the remaining binding reactivity after alpha-galactosidase treatment of the antigen. Removal of the N-linked glycosylation sites within the Fc portion of target IgG markedly reduced the antibody binding. The findings suggest that the carbohydrate content of the antigen is necessary for binding of the polyreactive IgG-RF MoAb. Reactivity to carbohydrate antigens may readily explain the so-called multispecificity of certain antibodies.
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PMID:Binding specificities of a polyreactive and a monoreactive human monoclonal IgG rheumatoid factor: role of oligosaccharides. 894 98

Recently introduced rapid nonmicroscopic immunocapture assays for the diagnosis of malaria infection are being evaluated for their sensitivity and specificity in various epidemiological settings. A Plasmodium falciparum histidine-rich protein 2 (PfHRP-2)-based assay (ICT) and a Plasmodium-specific lactate dehydrogenase test (OptiMAL) were evaluated for their specificities in different groups of patients who tested negative for malaria infection by microscopy. The patients were selected from different disease groups: rheumatoid arthritis, hepatitis C, toxoplasmosis, schistosomiasis, and hydatid disease. One hundred thirty-three of the 225 patients were positive for rheumatoid factor. Thirty-five of the 133 (26%) rheumatoid factor-positive patients gave a false-positive reaction with the ICT assay, but only 4 of these gave false-positive reactions with the OptiMAL test. Thirty-three of the 35 false-positive specimens became negative when repeat tested with the ICT assay after absorbing out the rheumatoid factor activity. Our study shows that the PfHRP-2-based ICT assay gave a false-positive reaction in 26% of the patients who had rheumatoid factors, but were negative for malaria by microscopy.
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PMID:Plasmodium falciparum histidine-rich protein 2-based immunocapture diagnostic assay for malaria: cross-reactivity with rheumatoid factors. 1069 18

A range of serological tests, including rapid plasma reagin (RPR), Widal test, enzyme-linked immunosorbent assay (ELISA) for human immunodeficiency virus (HIV)-1 and -2, direct Coombs' test (DCT), and rheumatoid factor (RF) were performed in a well-characterised cohort of 100 patients with acute malaria (Plasmodium vivax infection: 31 patients; P. falciparum infection: 69 patients). Twenty-five healthy volunteers from a similar area were used as controls. Three patients from the severe P. falciparum group died, the remainder of the patients recovered completely. A large proportion of these patients showed false-positive serological reactions during the acute stage of infection, which became negative on re-testing, four weeks after recovery. In tropical countries such as India, where malaria is endemic, results of serological tests should be interpreted with caution in a patient with pyrexia of unknown origin (PUO).
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PMID:False-positive serological tests in acute malaria. 1128 19


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