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 protective association between the human leukocyte antigen HLA-B53 and severe malaria was investigated by sequencing of peptides eluted from this molecule followed by screening of candidate epitopes from pre-erythrocytic-stage antigens of Plasmodium falciparum in biochemical and cellular assays. Among malaria-immune Africans, HLA-B53-restricted cytotoxic T lymphocytes recognized a conserved nonamer peptide from liver-stage-specific antigen-1 (LSA-1), but no HLA-B53-restricted epitopes were identified in other antigens. These findings indicate a possible molecular basis for this HLA-disease association and support the candidacy of liver-stage-specific antigen-1 as a malaria vaccine component.
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PMID:Molecular analysis of the association of HLA-B53 and resistance to severe malaria. 136 Jan 49

Patho-physiology of malaria is often presented with very old, rudimentary and not scientifically proved explanations. In fact, the mechanisms involved in malaria and mainly in cerebral malaria are very complex and, until now, partly unknown. Four hypotheses (sludging, modifications or blood-brain barrier permeability, mechanical or immunological phenomena) have to be considered. Several cytokines and mainly TNF seem to play the major role but other parameters are also essential in relation with Plasmodium (strain characteristics) or with the patient (HLA groups, immunological response). All technologies (immunology, iso-enzymology, molecular biology) bring new and important informations but, at the same time, make the issue ever more complex. Nevertheless, patho-physiology remains one of the most interesting aspects of malaria, both from a fundamental and a practical point of view, as fighting against this disease will probably become easier when we understand its mechanisms better.
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PMID:[Pathophysiology of malaria. The current issue]. 132 52

The pathophysiology of the anaemia of falciparum malaria is both complex and multifactorial, and results in a condition which is a major cause of mortality and morbidity in patients, especially children and pregnant women, living in malarial endemic areas. The importance of anaemia as a cause of death in malaria may well be underestimated because of difficulty in diagnosis, especially where parasitaemia may be low and the clinical picture may be confused with other causes of anaemia. Two clinical presentations predominate: severe acute malaria in which anaemia supervenes, and severe anaemia in patients in whom there have been repeated attacks of malaria. The major mechanisms are those of red cell destruction and decreased red cell production. Potential causes of haemolysis include loss of infected cells by rupture or phagocytosis, removal of uninfected cells due to antibody sensitization or other physicochemical membrane changes, and increased reticuloendothelial activity, particularly in organs such as the spleen. Decreased production results from marrow hypoplasia seen in acute infections, and dyserythropoiesis, a morphological appearance, which in functional terms results in ineffective erythropoiesis. The role of parvovirus B19 as a possible cause of bone marrow aplasia in a few cases is postulated. Finally, there is now evidence which points to genetic factors, HLA associated, which may protect against the development of malarial anaemia and which has become common in areas endemic for malaria.
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PMID:Anaemia of Plasmodium falciparum malaria. 151 Nov 78

In this study we examined the association of a promiscuous malaria T cell epitope, CS.T3, to different HLA-DR alleles. A large series of singly substituted or truncated variants of CS.T3 was prepared and tested for the ability to be recognised in association with, or to bind to, three distinct HLA-DR alleles (DR1, DRw11, and DRw14(w6)) and three natural variants of HLA-DRw11. We found that although association with the different DR molecules mapped to identical or closely overlapping regions of the peptide, distinct substitutions could drastically influence the capacity of the peptide to interact with one but not another of the three DR molecules tested. Based on analysis of the distribution of residues recognized by T cell clones restricted to the different DR alleles, we suggest that the peptide CS.T3 is not bound, at least for the three DR examined, as an alpha-helix. In addition we tested three subtypes of DRw11 as APC for the CS.T3 analogues and observed that the peptide is most likely bound in the same conformation to the three natural variants of the DRw11 molecule.
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PMID:Analysis of the permissive association of a malaria T cell epitope with DR molecules. 170 96

Using a complete series of overlapping peptides, we have identified the T cell epitopes of a malaria vaccine candidate, the circumsporozoite (CS) protein, that are recognized by sporozoite-exposed residents of a non-endemic country. This protein and subunits from it are being considered as malaria sporozoite vaccine candidates, as CS-specific antibodies and cytotoxic T lymphocytes have been shown to have a role in protection. The rationale for developing an antibody-based vaccine is that in Plasmodium falciparum the immunodominant B cell epitope of the protein, (Asn-Ala-Asn-Pro)n [(NANP)n], is invariant. However, the ideal vaccine must contain CS protein-derived T cell antigenic epitopes to allow natural boosting of the antibody response following sporozoite exposure. Here, we show that major differences occur between the CS-specific T cell responses of non-endemic Caucasians and an endemic African population. HLA differences between the populations are, in part, responsible. Subunit malaria vaccines for one population may be ineffective in a different population.
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PMID:Major population differences in T cell response to a malaria sporozoite vaccine candidate. 170 20

Although there are important obstacles to malaria vaccine development, we believe they might be overcome by a strategy of searching for conserved regions of a vaccine candidate that are recognized in association with many different HLA molecules and, if necessary, deliberately modifying the conserved sequences to improve their immunogenicity for T cells. This approach is illustrated by work on the circumsporozoite (CS) protein of Plasmodium falciparum, which covers the surface of the malaria sporozoite and is the best characterized of current vaccine candidates.
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PMID:An invariant, "universal" T-cell epitope in the P. falciparum circumsporozoite protein. 170 37

We have examined immune responses to a cultured Plasmodium falciparum gametocyte lysate and to an affinity-purified preparation of the 48/45-kDa gamete surface Ag in a group of 30 malaria immune individuals and in 24 Europeans with no previous exposure to malaria. Cellular responses were assessed in vitro by lymphoproliferation and production of IFN-gamma; antigamete antibodies were detected by immunofluorescence, Western blotting, and competitive ELISA. Cells from all the malaria immune donors responded to the gametocyte lysate in both assays while cells from nonimmune donors gave only weak proliferative responses. Antigamete antibodies were detected in the serum of all the immune donors but not in serum from nonimmunes. Nonimmune donors were completely unresponsive to the purified 48/45-kDa surface Ag while cells from 40% of immune donors responded by either proliferation or IFN-gamma production. Only 3 of 30 immune donors had detectable antibodies to the 48/45-kDa Ag. Class II HLA type was determined for 27 of the immune donors but no relationship between HLA-DR or -DQ and responsiveness to the 48/45-kDa Ag was discerned. The possible reasons for limited recognition of this gamete surface Ag are discussed.
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PMID:Cellular and humoral immune responses to Plasmodium falciparum gametocyte antigens in malaria-immune individuals. Limited response to the 48/45-kilodalton surface antigen does not appear to be due to MHC restriction. 211 74

Malaria is an important public health problem in developing countries. The production of a good vaccine needs a better knowledge of different mechanisms which control the immune system. Results from donors show a higher frequency of antigens HLA: A2, B35, CW4, CW6, DRW52, DQW1 and DQW3. The lymphoproliferation in vitro of mononuclear cells, T cells and CD4+ and CD8+ subsets T cells with merozoite extracts is not so clear to establish a correlation between HLA phenotypes and T cells response.
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PMID:[Research on malaria vaccine]. 213 5

Some enlarged spleens do not seem to be related with known pathogenetic mechanisms (passive congestion, functional workload, malignant infiltration and inflammatory or storage disorders). Non-tropical idiopathic splenomegaly (Dacie's syndrome) is a form of hypersplenism of unknown origin that evolves into a non-Hodgkin lymphoma, after a variable interval, in 20% of the patients. Tropical idiopathic splenomegaly (or hyperreactive malarial splenomegaly) develops when a chronic malarial challenge triggers an abnormal immunological response consisting in decreased suppressor T lymphocytes and increased amounts of circulating immunoglobulin M and immunocomplexes, which are cleared by the splenic macrophages. This peculiar response to malaria seems to be linked to particular HLA antigens. Other confusing splenomegalies are seen in Felty's syndrome, in populations subjected to recurrent infections, and in some families. Overlapping findings and diseases suggest chronic antigenic stimulation as a common feature, with diverse responses depending on the host. A small percentage (probably less than 3%) of normal individuals has minimal splenomegaly without any clinical significance.
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PMID:[Dacie syndrome and other splenomegalies without apparent cause]. 226 48

In the case of the malaria CS protein we have shown that there is at least one T cell determinant which is able to bind to and be recognized by most human MHC class II molecules, while for the 190L polypeptide, derived from a conserved region of the p190 merozoite surface protein, we have identified several epitopes recognized by T cell clones in association with different HLA-class II isotypes and alleles. In addition, binding analysis of these epitopes indicated that most of the peptides are able to bind to multiple allelic forms of class II molecules. Although there are important obstacles to malaria vaccine development we believe that, in the light of these results, unresponsiveness in humans, caused by MHC restriction, might not be a major constraint in development of a subunit vaccine.
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PMID:Malaria antigens and MHC restriction. 228 57


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