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Diouf I, Rodriguez Fonseca B, Caminade C, Thiaw WM, Deme A, Morse AP, Ndione JA, Gaye AT, Diaw A, Ndiaye MKN. Climate Variability and Malaria over West Africa. Am J Trop Med Hyg 2020; 102:1037-1047. [PMID: 32189612 PMCID: PMC7204584 DOI: 10.4269/ajtmh.19-0062] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 02/01/2020] [Indexed: 01/24/2023] Open
Abstract
Malaria is a major public health problem in West Africa. Previous studies have shown that climate variability significantly affects malaria transmission. The lack of continuous observed weather station data and the absence of surveillance data for malaria over long periods have led to the use of reanalysis data to drive malaria models. In this study, we use the Liverpool Malaria Model (LMM) to simulate spatiotemporal variability of malaria in West Africa using daily rainfall and temperature from the following: Twentieth Century Reanalysis (20th CR), National Center for Environmental Prediction (NCEP), European Centre for Medium-Range Weather Forecasts (ECMWF) Atmospheric Reanalysis of the Twentieth Century (ERA20C), and interim ECMWF Re-Analysis (ERA-Interim). Malaria case data from the national surveillance program in Senegal are used for model validation between 2001 and 2016. The warm temperatures found over the Sahelian fringe of West Africa can lead to high malaria transmission during wet years. The rainfall season peaks in July to September over West Africa and Senegal, and the malaria season lasts from September to November, about 1-2 months after the rainfall peak. The long-term trends exhibit interannual and decadal variabilities. The LMM shows acceptable performance in simulating the spatial distribution of malaria incidence. However, some discrepancies are found. These results are useful for decision-makers who plan public health and control measures in affected West African countries. The study would have substantial implications for directing malaria surveillance activities and health policy. In addition, this malaria modeling framework could lead to the development of an early warning system for malaria in West Africa.
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Affiliation(s)
- Ibrahima Diouf
- NOAA Center for Weather and Climate Prediction, College Park, Maryland
- Laboratoire de Physique de L’Atmosphère et de L’Océan-Siméon Fongang, Ecole Supérieure Polytechnique de L’Université Cheikh Anta Diop, Dakar, Sénégal
| | - Belén Rodriguez Fonseca
- Department of Geophysics and Meteorology, Universidad Complutense de Madrid, Madrid, Spain
- Instituto de Geociencias IGEO, CSIC-UCM, Agencia Estatal del Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Cyril Caminade
- Department of Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
- National Institute for Health Research [M1] (NIHR), Health Protection Research Unit in Emerging and Zoonotic Infections, Liverpool, United Kingdom
| | - Wassila M. Thiaw
- NOAA Center for Weather and Climate Prediction, College Park, Maryland
| | - Abdoulaye Deme
- Unité de Formation et de Recherche de Sciences Appliquées et de Technologie, Université Gaston Berger, Saint Louis, Sénégal
| | - Andrew P. Morse
- National Institute for Health Research [M1] (NIHR), Health Protection Research Unit in Emerging and Zoonotic Infections, Liverpool, United Kingdom
- Department of Geography and Planning, School of Environmental Sciences, University of Liverpool, Liverpool, United Kingdom
| | | | - Amadou Thierno Gaye
- Laboratoire de Physique de L’Atmosphère et de L’Océan-Siméon Fongang, Ecole Supérieure Polytechnique de L’Université Cheikh Anta Diop, Dakar, Sénégal
| | - Anta Diaw
- General Direction of Public Health, Ministry of Health and Social Action, Dakar, Senegal
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Joseph H, Tan QY, Mazhari R, Eriksson EM, Schofield L. Vaccine-Induced Carbohydrate-Specific Memory B Cells Reactivate During Rodent Malaria Infection. Front Immunol 2019; 10:1840. [PMID: 31447848 PMCID: PMC6696980 DOI: 10.3389/fimmu.2019.01840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 07/22/2019] [Indexed: 11/13/2022] Open
Abstract
A long-standing challenge in malaria is the limited understanding of B cell immunity, previously hampered by lack of tools to phenotype rare antigen-specific cells. Our aim was to develop a method for identifying carbohydrate-specific B cells within lymphocyte populations and to determine whether a candidate vaccine generated functional memory B cells (MBCs) that reactivated upon challenge with Plasmodium (pRBCs). To this end, a new flow cytometric probe was validated and used to determine the kinetics of B cell activation against the candidate vaccine glycosylphosphatidylinositol conjugated to Keyhole Limpet Haemocyanin (GPI-KLH). Additionally, immunized C57BL/6 mice were rested (10 weeks) and challenged with pRBCs or GPI-KLH to assess memory B cell recall against foreign antigen. We found that GPI-specific B cells were detectable in GPI-KLH vaccinated mice, but not in Plasmodium-infected mice. Additionally, in previously vaccinated mice GPI-specific IgG1 MBCs were reactivated against both pRBCs and synthetic GPI-KLH, which resulted in increased serum levels of anti-GPI IgG in both challenge approaches. Collectively our findings contribute to the understanding of B cell immunity in malaria and have important clinical implications for inclusion of carbohydrate conjugates in malaria vaccines.
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Affiliation(s)
- Hayley Joseph
- Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Qiao Ye Tan
- Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Ramin Mazhari
- Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Emily M Eriksson
- Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Louis Schofield
- Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, Australia.,Australian Institute of Tropical Health and Medicine, James Cook University, Townsville, QLD, Australia
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3
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Siau A, Huang X, Loh HP, Zhang N, Meng W, Sze SK, Renia L, Preiser P. Immunomic Identification of Malaria Antigens Associated With Protection in Mice. Mol Cell Proteomics 2019; 18:837-853. [PMID: 30718293 DOI: 10.1074/mcp.ra118.000997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 01/22/2019] [Indexed: 11/06/2022] Open
Abstract
Efforts to develop vaccines against malaria represent a major research target. The observations that 1) sterile protection can be obtained when the host is exposed to live parasites and 2) the immunity against blood stage parasite is principally mediated by protective antibodies suggest that a protective vaccine is feasible. However, only a small number of proteins have been investigated so far and most of the Plasmodium proteome has yet to be explored. To date, only few immunodominant antigens have emerged for testing in clinical trials but no formulation has led to substantial protection in humans. The nature of parasite molecules associated with protection remains elusive. Here, immunomic screening of mice immune sera with different protection efficiencies against the whole parasite proteome allowed us to identify a large repertoire of antigens validated by screening a library expressing antigens. The calculation of weighted scores reflecting the likelihood of protection of each antigen using five predictive criteria derived from immunomic and proteomic data sets, highlighted a priority list of protective antigens. Altogether, the approach sheds light on conserved antigens across Plasmodium that are amenable to targeting by the host immune system upon merozoite invasion and blood stage development. Most of these antigens have preliminary protection data but have not been widely considered as candidate for vaccine trials, opening new perspectives that overcome the limited choice of immunodominant, poorly protective vaccines currently being the focus of malaria vaccine researches.
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Affiliation(s)
- Anthony Siau
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;.
| | - Ximei Huang
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;; From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Han Ping Loh
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;; From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Neng Zhang
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Wei Meng
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Siu Kwan Sze
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Laurent Renia
- §Singapore Immunology Network (SIgN), A*STAR, Biopolis, Singapore
| | - Peter Preiser
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;.
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Abstract
Parasites of the genus Plasmodium have a complex life cycle. They alternate between their final mosquito host and their intermediate hosts. The parasite can be either extra- or intracellular, depending on the stage of development. By modifying their shape, motility, and metabolic requirements, the parasite adapts to the different environments in their different hosts. The parasite has evolved to escape the multiple immune mechanisms in the host that try to block parasite development at the different stages of their development. In this article, we describe the mechanisms reported thus far that allow the Plasmodium parasite to evade innate and adaptive immune responses.
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Affiliation(s)
- Laurent Rénia
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Yun Shan Goh
- Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Singapore
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5
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Peng K, Goh YS, Siau A, Franetich JF, Chia WN, Ong ASM, Malleret B, Wu YY, Snounou G, Hermsen CC, Adams JH, Mazier D, Preiser PR, Sauerwein RW, Grüner AC, Rénia L. Breadth of humoral response and antigenic targets of sporozoite-inhibitory antibodies associated with sterile protection induced by controlled human malaria infection. Cell Microbiol 2016; 18:1739-1750. [PMID: 27130708 DOI: 10.1111/cmi.12608] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 03/30/2016] [Accepted: 04/01/2016] [Indexed: 11/28/2022]
Abstract
The development of an effective malaria vaccine has remained elusive even until today. This is because of our incomplete understanding of the immune mechanisms that confer and/or correlate with protection. Human volunteers have been protected experimentally from a subsequent challenge by immunization with Plasmodium falciparum sporozoites under drug cover. Here, we demonstrate that sera from the protected individuals contain neutralizing antibodies against the pre-erythrocytic stage. To identify the antigen(s) recognized by these antibodies, a newly developed library of P. falciparum antigens was screened with the neutralizing sera. Antibodies from protected individuals recognized a broad antigenic repertoire of which three antigens, PfMAEBL, PfTRAP and PfSEA1 were recognized by most protected individuals. As a proof of principle, we demonstrated that anti-PfMAEBL antibodies block liver stage development in human hepatocytes. Thus, these antigens identified are promising targets for vaccine development against malaria.
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Affiliation(s)
- Kaitian Peng
- Laboratory of Pathogen Immunobiology, Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore
| | - Yun Shan Goh
- Laboratory of Pathogen Immunobiology, Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore
| | - Anthony Siau
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Jean-François Franetich
- Centre d'Immunologie et de Maladies Infectieuses (CIMI) - Paris, Institut National de la Santé et de la Recherche Médicale (Inserm) U1135 - Centre National de la Recherche Scientifique (CNRS) ERL 8255, F-75013, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, UPMC UMRS CR7, F-75005, Paris, France
| | - Wan Ni Chia
- Laboratory of Pathogen Immunobiology, Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore.,Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Alice Soh Meoy Ong
- Laboratory of Pathogen Immunobiology, Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore
| | - Benoit Malleret
- Laboratory of Pathogen Immunobiology, Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore
| | - Ying Ying Wu
- Laboratory of Pathogen Immunobiology, Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore
| | - Georges Snounou
- Centre d'Immunologie et de Maladies Infectieuses (CIMI) - Paris, Institut National de la Santé et de la Recherche Médicale (Inserm) U1135 - Centre National de la Recherche Scientifique (CNRS) ERL 8255, F-75013, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, UPMC UMRS CR7, F-75005, Paris, France
| | - Cornelus C Hermsen
- Department of Medical Microbiology, Radboud University, Nijmegen Medical Center, Nijmegen, Netherlands
| | - John H Adams
- Department of Global Health, College of Public Health, University of South Florida, Tampa, USA
| | - Dominique Mazier
- Centre d'Immunologie et de Maladies Infectieuses (CIMI) - Paris, Institut National de la Santé et de la Recherche Médicale (Inserm) U1135 - Centre National de la Recherche Scientifique (CNRS) ERL 8255, F-75013, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, UPMC UMRS CR7, F-75005, Paris, France.,AP HP, Centre Hospitalo-Universitaire Pitié-Salpêtrière, F-75013, Paris, France
| | - Peter R Preiser
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Robert W Sauerwein
- Department of Medical Microbiology, Radboud University, Nijmegen Medical Center, Nijmegen, Netherlands
| | - Anne-Charlotte Grüner
- Laboratory of Pathogen Immunobiology, Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore
| | - Laurent Rénia
- Laboratory of Pathogen Immunobiology, Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore.,Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Baird JK, Barcus MJ, Elyazar IRF, Bangs MJ, Maguire JD, Fryauff DJ, Richie TL, Kalalo W. Onset of clinical immunity toPlasmodium falciparumamong Javanese migrants to Indonesian Papua. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2013; 97:557-64. [PMID: 14511553 DOI: 10.1179/000349803225001472] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Onset of clinical immunity to Plasmodium falciparum occurred among Javanese migrants to Indonesian Papua. Surveillance of the 243 migrants investigated began on the day of their arrival in Indonesian Papua and continued for 33 months. Asexual parasitaemia without fever constituted objective evidence of clinical immunity. Compared with first infection, the odds ratio (OR) for not having fever at the fourth infection within 24 months was 3.2 [95% confidence interval (CI)=1.03-10.2; P=0.02]. The corresponding OR with fewer infections within 24 months was not distinguishable from 1.0. The level of the fourth parasitaemia within 24 months (N=58) was classified as 'high' or 'low' in relation to the median count at first infection (840 parasites/microl; N=187). Fourth parasitaemias that were low-but not those that were high (OR=1.8; CI=0.6-5.4; P=0.35)-were associated with dramatic protection from fever (OR=31; CI=3.5-1348; P=0.0001). Among the adult subjects, the risk of fever with low parasitaemia was significantly higher at the first infection than at the fourth (OR=12.6; CI=1.7-530; P=0.005), indicating the development of clinical immunity. A similar but less marked pattern appeared among the children investigated (OR=6.5; CI=0.8-285; P=0.06).
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Affiliation(s)
- J K Baird
- United States Naval Medical Research Unit No.2, American Embassy Jakarta, FPO AP 96520-8132, USA.
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7
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Kantele A, Siikamäki H, Hannila-Handelberg T, Laitinen K, Rombo L. Plasmodium falciparum--malaria in pregnant African immigrants often goes unrecognized. J Travel Med 2012; 19:380-2. [PMID: 23379709 DOI: 10.1111/j.1708-8305.2012.00651.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report four cases of asymptomatic Plasmodium falciparum malaria in pregnant African women. They had immigrated to Finland 3 to 13 months earlier. The disease was revealed only by anemia. The diagnosis relied on blood smear which showed a parasitemia <0.2% in three cases. Medical personnel should be informed about the possibility of afebrile forms of malaria in pregnant women even months after immigration. Very low levels of parasitemia may call for a more sensitive diagnostic approach such as polymerase chain reaction.
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Affiliation(s)
- Anu Kantele
- Division of Infectious Diseases, Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland.
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8
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Pratt-Riccio LR, Bianco-Junior C, Totino PRR, Perce-Da-Silva DDS, Silva LA, Riccio EKP, Ennes-Vidal V, Neves-Ferreira AGC, Perales J, Rocha SLGD, Dias-Da-Silva F, Ferreira-da-Cruz MDF, Daniel-Ribeiro CT, Oliveira-Ferreira JD, Theisen M, Carvalho LJDM, Banic DM. Antibodies against the Plasmodium falciparum glutamate-rich protein from naturally exposed individuals living in a Brazilian malaria-endemic area can inhibit in vitro parasite growth. Mem Inst Oswaldo Cruz 2011; 106 Suppl 1:34-43. [DOI: 10.1590/s0074-02762011000900005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 06/01/2011] [Indexed: 11/22/2022] Open
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Atieli HE, Zhou G, Afrane Y, Lee MC, Mwanzo I, Githeko AK, Yan G. Insecticide-treated net (ITN) ownership, usage, and malaria transmission in the highlands of western Kenya. Parasit Vectors 2011; 4:113. [PMID: 21682919 PMCID: PMC3135563 DOI: 10.1186/1756-3305-4-113] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 06/18/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-treated bed nets (ITNs) are known to be highly effective in reducing malaria morbidity and mortality. However, usage varies among households, and such variations in actual usage may seriously limit the potential impact of nets and cause spatial heterogeneity on malaria transmission. This study examined ITN ownership and underlying factors for among-household variation in use, and malaria transmission in two highland regions of western Kenya. METHODS Cross-sectional surveys were conducted on ITN ownership (possession), compliance (actual usage among those who own ITNs), and malaria infections in occupants of randomly sampled houses in the dry and the rainy seasons of 2009. RESULTS Despite ITN ownership reaching more than 71%, compliance was low at 56.3%. The compliance rate was significantly higher during the rainy season compared with the dry season (62% vs. 49.6%). Both malaria parasite prevalence (11.8% vs. 5.1%) and vector densities (1.0 vs.0.4 female/house/night) were significantly higher during the rainy season than during the dry season. Other important factors affecting the use of ITNs include: a household education level of at least primary school level, significantly high numbers of nuisance mosquitoes, and low indoor temperatures. Malaria prevalence in the rainy season was about 30% lower in ITN users than in non-ITN users, but this percentage was not significantly different during the dry season. CONCLUSION In malaria hypo-mesoendemic highland regions of western Kenya, the gap between ITNownership and usage is generally high with greater usage recorded during the high transmission season. Because of the low compliance among those who own ITNs, there is a need to sensitize households on sustained use of ITNs in order to optimize their role as a malaria control tool.
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Affiliation(s)
- Harrysone E Atieli
- Climate and Human Health Research Unit, Centre for Global Health Research, Kenya Medical Research Institute, PO Box 1578-40100, Kisumu, Kenya.
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10
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Parity and placental infection affect antibody responses against Plasmodium falciparum during pregnancy. Infect Immun 2011; 79:1654-9. [PMID: 21300778 DOI: 10.1128/iai.01000-10] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Women are at higher risk of Plasmodium falciparum infection when pregnant. The decreasing risk of malaria with subsequent pregnancies is attributed to parity-dependent acquisition of antibodies against placental parasites expressing variant surface antigens, VAR2CSA, that mediate placental sequestration through adhesion to chondroitin sulfate A (CSA). However, modulation of immunity during pregnancy may also contribute to increase the risk of malaria. We compared antibody responses among 30 Mozambican primigravidae and 60 multigravidae at delivery, 40 men, and 40 children. IgG levels were measured against the surface antigens of erythrocytes infected with P. falciparum isolated from 12 pregnant women (4 placental and 8 peripheral blood isolates) and 26 nonpregnant hosts. We also measured IgG levels against merozoite recombinant antigens and total IgG. Placental P. falciparum infection was associated with increased levels of total IgG as well as IgG levels against merozoite antigens and parasite isolates from pregnant and nonpregnant hosts. We therefore stratified comparisons of antibody levels by placental infection. Compared to multigravidae, uninfected primigravidae had lower total IgG as well as lower levels of IgGs against peripheral blood isolates from both pregnant and nonpregnant hosts. These differences were not explained by use of bed nets, season at delivery, neighborhood of residence, or age. Compared to men, infected primigravidae had higher levels of IgGs against isolates from pregnant women and CSA-binding lines but not against other isolates, supporting the concept of a pregnancy-specific development of immunity to these parasite variants. Results of this study show that parity and placental infection can modulate immune responses during pregnancy against malaria parasites.
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Muniz-Junqueira MI, Tosta CE. Stages of in vitro phagocytosis of Plasmodium falciparum-infected erythrocytes by human monocytes. Rev Soc Bras Med Trop 2009; 42:103-6. [DOI: 10.1590/s0037-86822009000200001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Accepted: 11/27/2008] [Indexed: 11/21/2022] Open
Abstract
Monocytes/macrophages play a critical role in the defense mechanisms against malaria parasites, and are the main cells responsible for the elimination of malaria parasites from the blood circulation. We carried out a microscope-aided evaluation of the stages of in vitro phagocytosis of Plasmodium falciparum-infected erythrocytes, by human monocytes. These cells were obtained from healthy adult individuals by means of centrifugation through a cushion of Percoll density medium and were incubated with erythrocytes infected with Plasmodium falciparum that had previously been incubated with a pool of anti-plasmodial immune serum. We described the stages of phagocytosis, starting from adherence of infected erythrocytes to the phagocyte membrane and ending with their destruction within the phagolisosomes of the monocytes. We observed that the different erythrocytic forms of the parasite were ingested by monocytes, and that the process of phagocytosis may be completed in around 30 minutes. Furthermore, we showed that phagocytosis may occur continuously, such that different phases of the process were observed in the same phagocyte.
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Differences in human antibody reactivity to Plasmodium falciparum variant surface antigens are dependent on age and malaria transmission intensity in northeastern Tanzania. Infect Immun 2008; 76:2706-14. [PMID: 18250179 DOI: 10.1128/iai.01401-06] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum variant surface antigens (VSA) are involved in the pathogenesis of malaria. Immunoglobulin G (IgG) with specificity for VSA (anti-VSA IgG) is therefore considered important for acquired immunity. To better understand the nature and dynamics of variant-specific IgG responses at population level, we conducted an immunoepidemiological study in nearby communities in northeastern Tanzania, situated at different altitudes and therefore exposed to different levels of P. falciparum transmission intensity. Samples of plasma and infected red blood cells (IRBC) were collected from 759 individuals aged 0 to 19 years. Plasma levels of IgG with specificity for VSA expressed by a panel of different parasite isolates were measured by flow cytometry, while the ability of plasma to inhibit IRBC adhesion to CD36 was examined in cellular assays. The level and repertoire of the heterologous anti-VSA IgG response developed dramatically in individuals at 1 to 2 years of age in the high-transmission area, reaching a maximum level at around 10 years of age; only a modest further increase was observed among older children and adults. In contrast, at lower levels of malaria transmission, anti-VSA IgG levels were lower and the repertoire was more narrow, and similar age- and transmission-dependent differences were observed with regard to the ability of the plasma samples to inhibit adhesion of IRBC to CD36. These differences indicate a strong and dynamic relationship between malaria exposure and functional characteristics of the variant-specific antibody response, which is likely to be important for protection against malaria.
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Abstract
Human immunodeficiency virus (HIV) and Plasmodium parasites are pathogens that induce significant perturbation and activation of the immune system. Due to their geographical overlap, there have been concerns that co-infection with the two pathogens may be a factor in the modification of their development, and in the severity and rate of disease progression that they induce. In this article, we have reviewed some of the studies that have addressed this topic and we have tried to provide immunological mechanisms to explain these potential interactions.
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Affiliation(s)
- L Rénia
- Institut Cochin, Département d'Immunologie, 75014 Paris, France.
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14
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Dunyo S, Milligan P, Edwards T, Sutherland C, Targett G, Pinder M. Gametocytaemia after drug treatment of asymptomatic Plasmodium falciparum. PLOS CLINICAL TRIALS 2006; 1:e20. [PMID: 17013431 PMCID: PMC1851719 DOI: 10.1371/journal.pctr.0010020] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Accepted: 07/06/2006] [Indexed: 11/18/2022]
Abstract
OBJECTIVES Treatment of Plasmodium falciparum malaria with sulfadoxine-pyrimethamine (SP) is followed by a sharp rise in the prevalence and density of gametocytes. We did a randomized trial to determine the effect of treatment of asymptomatic infections with SP or SP plus one dose of artesunate (SP+AS) on gametocyte carriage. DESIGN The study was a three-arm open-label randomized trial. We randomized asymptomatic carriers of P. falciparum to receive antimalarial treatment or placebo, and recorded the prevalence and density of gametocytes over the next 2 mo. SETTING The trial was conducted during the dry (low malaria transmission) season in four rural villages in Gambia. PARTICIPANTS Participants were adults and children aged over 6 mo with asexual P. falciparum infection and confirmed free of clinical symptoms of malaria over a 2-d screening period. INTERVENTIONS Participants were randomized to receive a single dose of SP or SP+AS or placebo. OUTCOME MEASURES The outcome measures were the presence of gametocytes 7 and 56 d after treatment, and the duration and density of gametocytaemia over 2 mo. RESULTS In total, 372 asymptomatic carriers were randomized. Gametocyte prevalence on day 7 was 10.5% in the placebo group, 11.2% in the SP group (risk difference to placebo 0.7%, 95% confidence interval -7.4% to 8.7%, p = 0.87), and 7.1% in the SP+AS group (risk difference to placebo 4.1%, 95% confidence interval -3.3% to 12%, p = 0.28). By day 56, gametocyte prevalence was 13% in the placebo group and 2% in both drug-treated groups. Gametocyte carriage (the area under the curve of gametocyte density versus time), was reduced by 71% in the SP group, and by 74% in the SP+AS group, compared to placebo. Gametocyte carriage varied with age and was greater among children under 15 than among adults. CONCLUSIONS Treatment of asymptomatic carriers of P. falciparum with SP does not increase gametocyte carriage or density. Effective treatment of asexual parasitaemia in the dry season reduces gametocyte carriage to very low levels after 4 wk.
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Affiliation(s)
- Samuel Dunyo
- Medical Research Council Laboratories, Banjul, Gambia
| | - Paul Milligan
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Tansy Edwards
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Colin Sutherland
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Geoffrey Targett
- London School of Hygiene and Tropical Medicine, London, United Kingdom
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15
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Basri H, Fryauff DJ, Barcus MJ, Bangs MJ, Ayomi E, Marwoto H, Elyazar IRF, Richie TL, Baird JK. Malaria in a cohort of Javanese migrants to Indonesian Papua. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2003; 97:543-56. [PMID: 14511552 DOI: 10.1179/000349803225001454] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The epidemiology of infection by Plasmodium falciparum and P. vivax was investigated among Javanese migrants to an endemic region of Papua, Indonesia. A cohort of 243 migrants from Java was followed for malaria in a new settlement village in the endemic Armopa area of north-eastern Papua, beginning on the day each migrant arrived in the village. The subjects were monitored during home visits (three/week) and by the twice-monthly production of bloodsmears that were checked for malarial parasites. At the end of 33 months, 159 (65%) of the subjects remained under follow-up. The prevalence of parasitaemia in the village declined from 16% among those already living there when the study began in August 1996, to 5% when the study finished in June 1999. Over this period, 596 infections by P. falciparum and 723 by P. vivax occurred in the cohort, 22 and 27 of the subjects each experiencing at least six infections by P. falciparum and P. vivax, respectively. The incidence of malarial infection was higher during the first and second years post-migration (3.2 and 2.7 infections/person-year) than during the third (1.2 infections/person-year). Although the geometric mean parasite counts for P. falciparum increased over time (1209, 1478, and 1830 parasites/microl in the first, second and third years, respectively), the corresponding values for P. vivax (497, 535 and 490 parasites/microl) showed no such trend. Only one of the nine subjects who developed severe malaria (requiring intravenous quinine therapy) was a child, giving an odds ratio for a case of severe malaria being in an adult of 6.1 (P=0.08).
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16
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17
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Urban BC, Mwangi T, Ross A, Kinyanjui S, Mosobo M, Kai O, Lowe B, Marsh K, Roberts DJ. Peripheral blood dendritic cells in children with acute Plasmodium falciparum malaria. Blood 2001; 98:2859-61. [PMID: 11675362 DOI: 10.1182/blood.v98.9.2859] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The importance of dendritic cells (DCs) for the initiation and regulation of immune responses not only to foreign organisms but also to the self has raised considerable interest in the qualitative and quantitative analysis of these cells in various human diseases. Plasmodium falciparum malaria is characterized by the poor induction of long-lasting protective immune responses. This study, therefore, investigated the percentage of peripheral blood DCs as lineage marker-negative and HLA-DR(+) or CD83(+) cells in healthy children and in children suffering from acute malaria in Kilifi, Kenya. Comparable percentages of CD83(+) DCs were found in peripheral blood of healthy children and children with malaria. However, the percentage of HLA-DR(+) peripheral blood DCs was significantly reduced in children with malaria. The results suggest that a proportion of peripheral blood DCs may be functionally impaired due to the low expression of HLA-DR on their surface.
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Affiliation(s)
- B C Urban
- Weatherall Institute of Molecular Medicine, Nuffield Department of Clinical Medicine, and National Blood Service, John Radcliffe Hospital, University of Oxford, United Kingdom.
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18
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Piper KP, Hayward RE, Cox MJ, Day KP. Malaria transmission and naturally acquired immunity to PfEMP-1. Infect Immun 1999; 67:6369-74. [PMID: 10569752 PMCID: PMC97044 DOI: 10.1128/iai.67.12.6369-6374.1999] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Why there are so few gametocytes (the transmission stage of malaria) in the blood of humans infected with Plasmodium spp. is intriguing. This may be due either to reproductive restraint by the parasite or to unidentified gametocyte-specific immune-mediated clearance mechanisms. We propose another mechanism, a cross-stage immunity to Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP-1). This molecule is expressed on the surface of the erythrocyte infected with either trophozoite or early gametocyte parasites. Immunoglobulin G antibodies to PfEMP-1, expressed on both life cycle stages, were measured in residents from an area where malaria is endemic, Papua New Guinea. Anti-PfEMP-1 prevalence increased with age, mirroring the decline in both the prevalence and the density of asexual and transmission stages in erythrocytes. These data led us to propose that immunity to PfEMP-1 may influence malaria transmission by regulation of the production of gametocytes. This regulation may be achieved in two ways: (i) by controlling asexual proliferation and density and (ii) by affecting gametocyte maturation.
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Affiliation(s)
- K P Piper
- Wellcome Trust Centre for the Epidemiology of Infectious Disease, Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom.
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19
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Gupta S, Snow RW, Donnelly CA, Marsh K, Newbold C. Immunity to non-cerebral severe malaria is acquired after one or two infections. Nat Med 1999; 5:340-3. [PMID: 10086393 DOI: 10.1038/6560] [Citation(s) in RCA: 290] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In areas of stable transmission, clinical immunity to mild malaria is acquired slowly, so it is not usually effective until early adolescence. Life-threatening disease is, however, restricted to a much younger age group, indicating that resistance to the severe clinical consequences of infection is acquired more quickly. Understanding how rapidly immunity develops to severe malaria is essential, as severe malaria should be the primary target of intervention strategies, and predicting the result of interventions that reduce host exposure will require consideration of these dynamics. Severe disease in childhood is less frequent in areas where transmission is the greatest. One explanation for this is that infants experience increased exposure to infection while they are protected from disease, possibly by maternal antibody. They therefore emerge from this period of clinical protection with considerably more immunity than those who experience lower transmission intensities. Here we use this data, assuming a period of clinical protection, to estimate the number of prior infections needed to reduce the risk of severe disease to negligible levels. Contrary to expectations, one or two successful infective bites seem to be all that is necessary across a broad range of transmission intensities.
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Affiliation(s)
- S Gupta
- Wellcome Trust Centre for Epidemiology of Infectious Disease, Department of Zoology, University of Oxford, UK
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20
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Slutsker L, Taylor TE, Wirima JJ, Steketee RW. In-hospital morbidity and mortality due to malaria-associated severe anaemia in two areas of Malawi with different patterns of malaria infection. Trans R Soc Trop Med Hyg 1994; 88:548-51. [PMID: 7992335 DOI: 10.1016/0035-9203(94)90157-0] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We examined the relative contribution of malaria-associated severe anaemia (parasitaemia and haematocrit < or = 15%) to malaria-related morbidity and mortality among children admitted at 2 hospitals in areas with different seasonal patterns of malaria infection in Malawi. The prevalence of malaria-associated severe anaemia was 8.5% among admissions at the hospital in an area with sustained, year-round infection (Mangochi District Hospital [MDH]), compared to 5.2% at the hospital in an area with a fluctuating pattern of infection (Queen Elizabeth Central Hospital [QECH]). Infants at MDH were nearly twice as likely to have malaria-associated severe anaemia as were those at QECH. Parasite density on admission was not related to the risk of severe anaemia at MDH, but it was at QECH. A similar proportion of all deaths was attributed to malaria at MDH (17.5%) and QECH (20.4%). However, malaria-associated severe anaemia accounted for 54% of malaria-related deaths at MDH compared to only 32% at QECH. Malaria-associated severe anaemia contributed significantly to morbidity and mortality at both sites, but its impact was more marked in the area with a sustained pattern of infection. These findings suggest that seasonal fluctuations in malaria infection may contribute to differences in patterns of malaria disease.
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Affiliation(s)
- L Slutsker
- Malaria Branch, Centers for Disease Control, Atlanta, GA 30333
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21
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Zevering Y, Khamboonruang C, Good MF. Natural amino acid polymorphisms of the circumsporozoite protein of Plasmodium falciparum abrogate specific human CD4+ T cell responsiveness. Eur J Immunol 1994; 24:1418-25. [PMID: 7911423 DOI: 10.1002/eji.1830240627] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Sequence polymorphism has been reported for virtually all malaria antigens and, in the case of the circumsporozoite (CS) protein, this variation is in the form of point mutations concentrated primarily in several regions recognized by T cells. The factors responsible for the variation are unknown. We studied the T cell responses to all known variants in malaria-exposed Thais. Memory CD4+ T cells responded to variants of a polymorphic immunodominant region (denoted Th2R), and CD4+ T cell clones specific for one Thai Th2R variant were generated. There was minimal cross-reactivity to any of the naturally occurring variants, including the other Thai variant, and competition studies performed with the clones using analog peptides demonstrated that all the substitutions of the polymorphic residues modulate either the binding of the peptide to major histocompatibility complex (MHC) molecules or the recognition by the T cell receptor of the peptide-MHC complex. Our data suggest that CD4+ T cells may be able to select parasites expressing variant sequences and have implications for development of a CS-based vaccine.
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Affiliation(s)
- Y Zevering
- Molecular Immunology Laboratory, Queensland Institute of Medical Research, Brisbane, QLD, Australia
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Mshana RN, Boulandi J, Mayombo J, Mendome G. In vitro lymphoproliferative responses to malaria antigens: a prospective study of residents of a holoendemic area with perennial malaria transmission. Parasite Immunol 1993; 15:35-45. [PMID: 8094548 DOI: 10.1111/j.1365-3024.1993.tb00570.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A longitudinal, prospective study to examine the relationship between the outcome of infection with Plasmodium falciparum parasites and in vitro T-cell proliferative responses to a P. falciparum schizont extract (PfSE) was conducted in a village in south-eastern Gabon, an area where malaria is holoendemic and transmission is intense and perennial. The donor's age was found to have a strong independent influence on all malariometric indices. At the community level, the in vitro lymphoproliferative response to PfSE was bimodal with 30% of the villagers studied showing persistently low responses. The frequency of low or high responders within the study population did not show any consistent relationship with the community parasite rates or the number of either patent parasitaemic episodes or clinical malarial attacks per individual. At the individual donor level, the response was negatively correlated with P. falciparum parasite density in those donors who were parasitaemic at the time of sampling. High in vitro lymphoproliferative responses to PfSE were predictive of resistance to clinical malaria. The PfSE-induced in vitro lymphoproliferative response was dependent on antigen presenting cells, CD4+ T-cells and UCHL-1+ cells.
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Affiliation(s)
- R N Mshana
- Department of Immunoparasitology, International Centre for Medical Research (CIRMF), Franceville, The Gabon
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24
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Früh K, Doumbo O, Müller HM, Koita O, McBride J, Crisanti A, Touré Y, Bujard H. Human antibody response to the major merozoite surface antigen of Plasmodium falciparum is strain specific and short-lived. Infect Immun 1991; 59:1319-24. [PMID: 2004813 PMCID: PMC257845 DOI: 10.1128/iai.59.4.1319-1324.1991] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The precursor of the major merozoite antigen of Plasmodium falciparum, gp190, is considered a candidate for inclusion in a malaria vaccine. This protein, which consists of conserved, dimorphic, and polymorphic sequences, is very immunogenic in humans. In a longitudinal study carried out with 94 inhabitants of a rural community in Mali, West Africa, we show that in this endemic area naturally acquired gp190-specific antibodies are predominantly directed against the dimorphic parts of one of the main alleles of gp190. The presence of antibodies against these dimorphic regions correlates with the prevalence of the corresponding antigen in the infecting parasite population. Moreover, qualitative as well as quantitative differences were found in the time course of the humoral immune response to the dimorphic regions in adults and children, who differ in their susceptibility to malaria infection.
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Affiliation(s)
- K Früh
- Zentrum für Molekulare Biologie, Heidelberg, Federal Republic of Germany
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25
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Eze MO. Avoidance, and inactivation of reactive oxygen species: novel microbial immune evasion strategies. Med Hypotheses 1991; 34:252-5. [PMID: 2062259 DOI: 10.1016/0306-9877(91)90219-o] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A prominent aspect of host cell-mediated immune (CMI) reactions leading to the clearance of infections is the production of one or more reactive oxygen species (ROS) such as superoxide (O2-), hydrogen peroxide (H2O2), hydroxyl radical (OH.), and hypohalite (e.g., OC1-). These ROS are usually produced by phagocytes. A number of chemotherapeutic agents also produce ROS in the process of their curative mechanisms. In a variety of infections, these ROS constitute a formidable arsenal in the clearance of the infection. In some cases, the excess ROS could also cause tissue damage. Evidence is herewith presented that pathogenic intracellular microorganisms, in order to enhance their survival as well as effective virulence within the host, have evolved novel strategies in the nature of avoidance, or inhibition of ROS production by phagocytes, or neutralization of already produced ROS. It is advocated that more in depth studies be undertaken in these respects in order to be able to exploit these phenomena in the production of more efficacious chemotherapeutic agents and anti-pathogen vaccines.
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Affiliation(s)
- M O Eze
- Department of Biochemistry, University of Nigeria, Nsukka
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26
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Nodiff EA, Chatterjee S, Musallam HA. Antimalarial activity of the 8-aminoquinolines. PROGRESS IN MEDICINAL CHEMISTRY 1991; 28:1-40. [PMID: 1843545 DOI: 10.1016/s0079-6468(08)70362-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- E A Nodiff
- Franklin Research Center, Arvin Calspan Corporation, Norristown, PA 19403
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27
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Schneweis S, Maier WA, Seitz HM. Haemolysis of infected erythrocytes--a trigger for formation of Plasmodium falciparum gametocytes? Parasitol Res 1991; 77:458-60. [PMID: 1891456 DOI: 10.1007/bf00931646] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- S Schneweis
- Institut für Medizinische Parasitologie, Bonn-Venusberg, Federal Republic of Germany
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28
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Lienhardt C, Ghebray R, Candolfi E, Kien T, Hedlin G. Malaria in refugee camps in eastern Sudan: a sero-epidemiological approach. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 1990; 84:215-22. [PMID: 2222023 DOI: 10.1080/00034983.1990.11812460] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A study of the endemicity of malaria was carried out in two refugee camps in Sudan, and the advantages and disadvantages of treating either all febrile cases or only confirmed cases of malaria were considered. Based on the information obtained during the survey, guidelines for the treatment of malaria in such refugee camps are proposed.
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29
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Elueze EI, Osisanya JO, Edafiogho IO. Sensitivity to chloroquine in vivo and in vitro of Plasmodium falciparum in Sokoto, Nigeria. Trans R Soc Trop Med Hyg 1990; 84:45. [PMID: 2189245 DOI: 10.1016/0035-9203(90)90375-o] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- E I Elueze
- College of Health Sciences, Usmanu Danfodiyo University, Sokoto, Nigeria
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30
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Kremsner PG, Feldmeier H, Zotter GM, Jansen-Rosseck R, Graninger W, Rocha RM, Bienzle U. Immunological alterations in uncomplicated Plasmodium falciparum malaria. Relationship between parasitaemia and indicators of macrophage activation. Acta Trop 1989; 46:351-9. [PMID: 2575870 DOI: 10.1016/0001-706x(89)90047-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Numerical alterations of circulating lymphocytes were investigated in 37 Brazilian patients with uncomplicated Plasmodium falciparum malaria and in a group of 15 healthy controls. The number of CD4+ T helper/inducer cells was significantly lower in patients than controls, whereas absolute numbers of CD8+ suppressor/cytotoxic T cells did not differ between the groups. TNF and neopterin levels were markedly increased in the plasma of patients and remained slightly elevated after chemotherapy with clindamycin. Neopterin, but not TNF levels, were significantly correlated with parasitaemia. TNF was inversely related to monocyte counts. Interferon gamma could not be detected in the plasma of control subjects and was observed in only one patient. We conclude that in uncomplicated falciparum malaria the distribution of phenotypes of circulating lymphocytes are altered slightly and that the high plasma levels of TNF and neopterin indicate excessive release of these molecules by activated macrophages and the activation of cellular immune mechanisms during the infection.
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Affiliation(s)
- P G Kremsner
- Landesinstitut für Tropenmedizin, Berlin, Germany
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