{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T18:16:37Z","timestamp":1770228997130,"version":"3.49.0"},"reference-count":70,"publisher":"Public Library of Science (PLoS)","issue":"9","license":[{"start":{"date-parts":[[2025,9,11]],"date-time":"2025-09-11T00:00:00Z","timestamp":1757548800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001713","name":"European and Developing Countries Clinical Trials Partnership","doi-asserted-by":"publisher","award":["RIA2020EF-3042"],"award-info":[{"award-number":["RIA2020EF-3042"]}],"id":[{"id":"10.13039\/501100001713","id-type":"DOI","asserted-by":"publisher"}]},{"name":"National Institute for Health and Care Research Global Health Research Professorship","award":["NIHR300791"],"award-info":[{"award-number":["NIHR300791"]}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:sec id=\"sec001\">\n<jats:title>Introduction<\/jats:title>\n<jats:p>COVID-19 was less severe in Sub-Saharan Africa (SSA) compared with Europe and North America. It is unclear whether these differences could be explained immunologically. Here we determined levels of <jats:italic><jats:italic>ex vivo<\/jats:italic><\/jats:italic> SARS-CoV-2 peptide-specific IFN-\u03b3 producing cells, and plasma cytokines and chemokines over the first month of COVID-19 diagnosis among Kenyan COVID-19 patients from urban and rural areas.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec002\">\n<jats:title>Methods<\/jats:title>\n<jats:p>Between June 2020 and August 2022, we recruited and longitudinally monitored 188 COVID-19 patients from two regions in Kenya, Nairobi (urban, n\u2009=\u2009152) and Kilifi (rural, n\u2009=\u200936), with varying disease severity \u2013 severe, mild\/moderate, and asymptomatic. IFN-\u03b3 secreting cells were enumerated at 0-, 7-, 14- and 28-days post diagnosis by an <jats:italic><jats:italic>ex vivo<\/jats:italic><\/jats:italic> enzyme-linked immunospot (ELISpot) assay following <jats:italic><jats:italic>in vitro<\/jats:italic><\/jats:italic> stimulation of peripheral blood mononuclear cells (PBMCs) with overlapping peptides from several SARS-CoV-2 proteins. A multiplexed binding assay was used to measure levels of 22 plasma cytokines and chemokines.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec003\">\n<jats:title>Results<\/jats:title>\n<jats:p>Higher frequencies of IFN-\u03b3-secreting cells against SARS-CoV-2 spike peptides were observed on the day of diagnosis among asymptomatic compared to patients with severe COVID-19. Higher concentrations of 17 of the 22 cytokines and chemokines measured were positively associated with severe disease, particularly interleukin (IL)-8, IL-18 and IL-1ra (p\u2009&lt;\u20090.0001), while a lower concentration of SDF-1\u03b1 was associated with severe disease (p\u2009&lt;\u20090.0001). Concentrations of 8 and 16 cytokines and chemokines including IL-18 were higher among Nairobi asymptomatic and mild patients compared to their respective Kilifi counterparts. Conversely, concentrations for SDF-1\u03b1 were higher in rural Kilifi compared to Nairobi (p\u2009=\u20090.012).<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec004\">\n<jats:title>Conclusion<\/jats:title>\n<jats:p>In Kenya, as seen elsewhere, pro-inflammatory cytokines and chemokines were associated with severe COVID-19, while an early IFN-\u03b3 cellular response to overlapping SARS-CoV-2 spike peptides was associated with reduced risk of disease. Living in urban Nairobi (compared with rural Kilifi) was associated with increased levels of pro-inflammatory cytokines and chemokines.<\/jats:p>\n<\/jats:sec>","DOI":"10.1371\/journal.pone.0316967","type":"journal-article","created":{"date-parts":[[2025,9,11]],"date-time":"2025-09-11T17:28:56Z","timestamp":1757611736000},"page":"e0316967","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":2,"title":["Induction of an early IFN-\u03b3 cellular response and high plasma levels of SDF-1\u03b1 are inversely associated with COVID-19 severity and residence in rural areas in Kenyan patients"],"prefix":"10.1371","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9293-0181","authenticated-orcid":true,"given":"Perpetual","family":"Wanjiku","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Benedict","family":"Orindi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"John","family":"Kimotho","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shahin","family":"Sayed","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1729-5012","authenticated-orcid":true,"given":"Reena","family":"Shah","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mansoor","family":"Saleh","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jedidah","family":"Mwacharo","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Christopher","family":"Maronga","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Viviane","family":"Olouch","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ann","family":"Karanu","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jasmit","family":"Shah","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zaitun","family":"Nneka","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lynette Isabella","family":"Ochola-Oyier","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Abdirahman I.","family":"Abdi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Susanna","family":"Dunachie","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Philip","family":"Bejon","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eunice W.","family":"Nduati","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Francis M.","family":"Ndungu","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2025,9,11]]},"reference":[{"issue":"8","key":"pone.0316967.ref001","doi-asserted-by":"crossref","DOI":"10.1016\/S2214-109X(22)00233-9","article-title":"COVID-19 in the 47 countries of the WHO African region: a modelling analysis of past trends and future patterns","volume":"10","author":"JW Cabore","year":"2022","journal-title":"Lancet Glob Health"},{"issue":"0","key":"pone.0316967.ref002","article-title":"Rethinking the evidence on COVID-19 in Africa","volume":"0","author":"P Bejon","year":"2025","journal-title":"Lancet Infect Dis"},{"issue":"6524","key":"pone.0316967.ref003","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1126\/science.abf8832","article-title":"The puzzle of the COVID-19 pandemic in Africa","volume":"371","author":"JM Maeda","year":"2021","journal-title":"Science"},{"issue":"3","key":"pone.0316967.ref004","doi-asserted-by":"crossref","first-page":"799","DOI":"10.1007\/s41748-021-00234-5","article-title":"A geographical analysis of the African COVID-19 paradox: putting the poverty-as-a-vaccine hypothesis to the test","volume":"5","author":"T Osayomi","year":"2021","journal-title":"Earth Syst Environ"},{"issue":"5","key":"pone.0316967.ref005","article-title":"The relatively young and rural population may limit the spread and severity of COVID-19 in Africa: a modelling study","volume":"5","author":"BZ Diop","year":"2020","journal-title":"BMJ Glob Health"},{"issue":"16","key":"pone.0316967.ref006","doi-asserted-by":"crossref","first-page":"8638","DOI":"10.3390\/ijerph18168638","article-title":"What Could Explain the Lower COVID-19 Burden in Africa despite Considerable Circulation of the SARS-CoV-2 Virus?","volume":"18","author":"RG Wamai","year":"2021","journal-title":"Int J Environ Res Public Health"},{"issue":"4","key":"pone.0316967.ref007","doi-asserted-by":"crossref","DOI":"10.1016\/S2666-5247(22)00295-6","article-title":"Peptide microarray IgM and IgG screening of pre-SARS-CoV-2 human serum samples from Zimbabwe for reactivity with peptides from all seven human coronaviruses: a cross-sectional study","volume":"4","author":"J Ashworth","year":"2023","journal-title":"Lancet Microbe"},{"issue":"7833","key":"pone.0316967.ref008","doi-asserted-by":"crossref","first-page":"270","DOI":"10.1038\/s41586-020-2598-9","article-title":"SARS-CoV-2-reactive T cells in healthy donors and patients with COVID-19","volume":"587","author":"J Braun","year":"2020","journal-title":"Nature"},{"issue":"7821","key":"pone.0316967.ref009","doi-asserted-by":"crossref","first-page":"457","DOI":"10.1038\/s41586-020-2550-z","article-title":"SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls","volume":"584","author":"N Le Bert","year":"2020","journal-title":"Nature"},{"issue":"7","key":"pone.0316967.ref010","doi-asserted-by":"crossref","first-page":"1489","DOI":"10.1016\/j.cell.2020.05.015","article-title":"Targets of T Cell Responses to SARS-CoV-2 Coronavirus in Humans with COVID-19 Disease and Unexposed Individuals","volume":"181","author":"A Grifoni","year":"2020","journal-title":"Cell"},{"issue":"48","key":"pone.0316967.ref011","doi-asserted-by":"crossref","DOI":"10.1126\/sciimmunol.abd2071","article-title":"Phenotype and kinetics of SARS-CoV-2-specific T cells in COVID-19 patients with acute respiratory distress syndrome","volume":"5","author":"D Weiskopf","year":"2020","journal-title":"Sci Immunol"},{"issue":"6512","key":"pone.0316967.ref012","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1126\/science.abd3871","article-title":"Selective and cross-reactive SARS-CoV-2 T cell epitopes in unexposed humans","volume":"370","author":"J Mateus","year":"2020","journal-title":"Science"},{"key":"pone.0316967.ref013","doi-asserted-by":"crossref","first-page":"106695","DOI":"10.1016\/j.envint.2021.106695","article-title":"SARS-CoV-2 and helminth co-infections, and environmental pollution exposure: An epidemiological and immunological perspective","volume":"156","author":"P Naidoo","year":"2021","journal-title":"Environ Int"},{"issue":"1","key":"pone.0316967.ref014","doi-asserted-by":"crossref","first-page":"975","DOI":"10.1186\/s12879-021-06701-8","article-title":"The association between malaria prevalence and COVID-19 mortality","volume":"21","author":"MU Anyanwu","year":"2021","journal-title":"BMC Infect Dis"},{"issue":"2","key":"pone.0316967.ref015","doi-asserted-by":"crossref","first-page":"100942","DOI":"10.1016\/j.lanmic.2024.07.005","article-title":"Immune responses to SARS-CoV-2 in sub-Saharan Africa and western Europe: a retrospective, population-based, cross-sectional study","volume":"6","author":"M Mbow","year":"2025","journal-title":"Lancet Microbe"},{"issue":"3","key":"pone.0316967.ref016","first-page":"382","article-title":"Virus-cell interactions: impact on cytokine production, immune evasion and tumor growth","volume":"12","author":"TH Mogensen","year":"2001","journal-title":"Eur Cytokine Netw"},{"issue":"1","key":"pone.0316967.ref017","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1128\/MMBR.65.1.131-150.2001","article-title":"Molecular pathways in virus-induced cytokine production","volume":"65","author":"TH Mogensen","year":"2001","journal-title":"Microbiol Mol Biol Rev"},{"issue":"6","key":"pone.0316967.ref018","doi-asserted-by":"crossref","first-page":"607","DOI":"10.1016\/j.jinf.2020.03.037","article-title":"The pathogenesis and treatment of the `Cytokine Storm\u2019 in COVID-19","volume":"80","author":"Q Ye","year":"2020","journal-title":"J Infect"},{"issue":"10223","key":"pone.0316967.ref019","doi-asserted-by":"crossref","first-page":"497","DOI":"10.1016\/S0140-6736(20)30183-5","article-title":"Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China","volume":"395","author":"C Huang","year":"2020","journal-title":"Lancet"},{"issue":"5","key":"pone.0316967.ref020","doi-asserted-by":"crossref","first-page":"746","DOI":"10.1093\/infdis\/jiaa363","article-title":"Serum cytokine and chemokine profile in relation to the severity of coronavirus disease 2019 in China","volume":"222","author":"Y Chi","year":"2020","journal-title":"J Infect Dis"},{"issue":"15","key":"pone.0316967.ref021","doi-asserted-by":"crossref","first-page":"762","DOI":"10.1093\/cid\/ciaa248","article-title":"Dysregulation of Immune Response in Patients With Coronavirus 2019 (COVID-19) in Wuhan, China","volume":"71","author":"C Qin","year":"2020","journal-title":"Clin Infect Dis Off Publ Infect Dis Soc Am"},{"key":"pone.0316967.ref022","doi-asserted-by":"crossref","DOI":"10.1177\/03946320231163681","article-title":"Patterns of cytokine and chemokine expression in peripheral blood of patients with COVID-19 associated with disease severity","volume":"37","author":"I Trifonova","year":"2023","journal-title":"Int J Immunopathol Pharmacol"},{"issue":"15","key":"pone.0316967.ref023","doi-asserted-by":"crossref","first-page":"12272","DOI":"10.3390\/ijms241512272","article-title":"Cytokine kinetics during progression of COVID-19 in Rwanda patients: could IL-9\/IFN\u03b3 ratio predict disease severity?","volume":"24","author":"EL Ndoricyimpaye","year":"2023","journal-title":"Int J Mol Sci"},{"key":"pone.0316967.ref024","article-title":"Longitudinal Cytokine Profile in Patients With Mild to Critical COVID-19","author":"L Ling","year":"2021","journal-title":"Front Immunol"},{"key":"pone.0316967.ref025","doi-asserted-by":"crossref","first-page":"102763","DOI":"10.1016\/j.ebiom.2020.102763","article-title":"Longitudinal characteristics of lymphocyte responses and cytokine profiles in the peripheral blood of SARS-CoV-2 infected patients","volume":"55","author":"J Liu","year":"2020","journal-title":"EBioMedicine"},{"issue":"57","key":"pone.0316967.ref026","doi-asserted-by":"crossref","DOI":"10.1126\/sciimmunol.abg9873","article-title":"Inflammatory profiles across the spectrum of disease reveal a distinct role for GM-CSF in severe COVID-19","volume":"6","author":"RS Thwaites","year":"2021","journal-title":"Sci Immunol"},{"key":"pone.0316967.ref027","doi-asserted-by":"crossref","first-page":"104799","DOI":"10.1016\/j.micpath.2021.104799","article-title":"The pro-inflammatory cytokines in COVID-19 pathogenesis: What goes wrong?","volume":"153","author":"D Darif","year":"2021","journal-title":"Microb Pathog"},{"issue":"7","key":"pone.0316967.ref028","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0288557","article-title":"Kinetics of specific anti-SARS-CoV-2 IgM, IgA, and IgG responses during the first 12 months after SARS-CoV-2 infection: A prospective longitudinal study","volume":"18","author":"H Amellal","year":"2023","journal-title":"PLoS One"},{"key":"pone.0316967.ref029","doi-asserted-by":"crossref","first-page":"350","DOI":"10.12688\/wellcomeopenres.19414.1","article-title":"Kinetics of naturally induced binding and neutralising anti-SARS-CoV-2 antibody levels and potencies among SARS-CoV-2 infected Kenyans with diverse grades of COVID-19 severity: an observational study","volume":"8","author":"J Kimotho","year":"2023","journal-title":"Wellcome Open Res"},{"issue":"4","key":"pone.0316967.ref030","doi-asserted-by":"crossref","first-page":"861","DOI":"10.1016\/j.cell.2021.01.007","article-title":"Adaptive immunity to SARS-CoV-2 and COVID-19","volume":"184","author":"A Sette","year":"2021","journal-title":"Cell"},{"key":"pone.0316967.ref031","doi-asserted-by":"crossref","first-page":"156917","DOI":"10.1016\/j.cyto.2025.156917","article-title":"Cytokine immune profiles among COVID 19 patients with different disease severities seeking treatment at Moi teaching and referral hospital, Kenya","volume":"190","author":"JC Sang","year":"2025","journal-title":"Cytokine"},{"issue":"13","key":"pone.0316967.ref032","doi-asserted-by":"crossref","DOI":"10.1172\/JCI170011","article-title":"Prevalence and functional profile of SARS-CoV-2 T cells in asymptomatic Kenyan adults","volume":"133","author":"T Samandari","year":"2023","journal-title":"J Clin Invest"},{"issue":"6570","key":"pone.0316967.ref033","doi-asserted-by":"crossref","first-page":"989","DOI":"10.1126\/science.abk0414","article-title":"COVID-19 transmission dynamics underlying epidemic waves in Kenya","volume":"374","author":"SPC Brand","year":"2021","journal-title":"Science"},{"key":"pone.0316967.ref034","unstructured":"NIH. COVID-19 Treatment Guidelines. Available from: https:\/\/www.covid19treatmentguidelines.nih.gov\/overview\/clinical-spectrum\/. 2021."},{"issue":"1","key":"pone.0316967.ref035","doi-asserted-by":"crossref","DOI":"10.1016\/S2666-5247(21)00275-5","article-title":"T-cell and antibody responses to first BNT162b2 vaccine dose in previously infected and SARS-CoV-2-naive UK health-care workers: a multicentre prospective cohort study","volume":"3","author":"A Angyal","year":"2022","journal-title":"Lancet Microbe"},{"key":"pone.0316967.ref036","author":"Merck KGaA","year":"2022"},{"key":"pone.0316967.ref037","doi-asserted-by":"crossref","DOI":"10.1017\/CBO9780511790942","volume-title":"Data analysis using regression and multilevel\/hierarchical models","author":"A Gelman","year":"2006"},{"key":"pone.0316967.ref038","volume-title":"Statistical analysis with missing data","author":"RJA Little","year":"2019"},{"key":"pone.0316967.ref039","unstructured":"R C, Team. R: A language and environment for statistical computing. Available from: https:\/\/www.R-project.org\/. 2023."},{"key":"pone.0316967.ref040","unstructured":"Kassambara A, Mundt F. Factoextra: Extract and visualize the results of multivariate data analyses. Available from: https:\/\/CRAN.R-project.org\/package=factoextra. 2020."},{"key":"pone.0316967.ref041","unstructured":"Kolde R. pheatmap: Pretty heatmaps. Available from: https:\/\/cran.r-project.org\/web\/packages\/pheatmap\/index.html. 2019."},{"key":"pone.0316967.ref042","doi-asserted-by":"crossref","DOI":"10.1007\/978-3-319-24277-4","author":"H Wickham","year":"2016","journal-title":"ggplot2. Springer International Publishing"},{"key":"pone.0316967.ref043","unstructured":"Graph p a d prism programming team. Graph pad prism. Available from: https:\/\/www.graphpad.com\/features. 2023."},{"issue":"6","key":"pone.0316967.ref044","doi-asserted-by":"crossref","first-page":"108728","DOI":"10.1016\/j.celrep.2021.108728","article-title":"Early induction of functional SARS-CoV-2-specific T cells associates with rapid viral clearance and mild disease in COVID-19 patients","volume":"34","author":"AT Tan","year":"2021","journal-title":"Cell Rep"},{"key":"pone.0316967.ref045","article-title":"Impaired SARS-CoV-2 specific T-cell response in patients with severe COVID-19","author":"LW R\u00fcmke","year":"2023","journal-title":"Front Immunol"},{"issue":"2","key":"pone.0316967.ref046","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0281444","article-title":"Severe and mild-moderate SARS-CoV-2 vaccinated patients show different frequencies of IFN\u03b3-releasing cells: An exploratory study","volume":"18","author":"E Garofalo","year":"2023","journal-title":"PLoS One"},{"issue":"1","key":"pone.0316967.ref047","doi-asserted-by":"crossref","first-page":"612","DOI":"10.1186\/s12879-024-09490-y","article-title":"T cell-mediated Immune response and correlates of inflammation and their relationship with COVID-19 clinical severity: not an intuitive guess","volume":"24","author":"NM Pena","year":"2024","journal-title":"BMC Infect Dis"},{"key":"pone.0316967.ref048","article-title":"Dynamic SARS-CoV-2-specific immunity in critically ill patients with hypertension","author":"Q Zeng","year":"2020","journal-title":"Front Immunol"},{"issue":"3","key":"pone.0316967.ref049","doi-asserted-by":"crossref","first-page":"109414","DOI":"10.1016\/j.celrep.2021.109414","article-title":"Distinctive features of SARS-CoV-2-specific T cells predict recovery from severe COVID-19","volume":"36","author":"J Neidleman","year":"2021","journal-title":"Cell Rep"},{"issue":"5","key":"pone.0316967.ref050","doi-asserted-by":"crossref","first-page":"3463","DOI":"10.4049\/jimmunol.0802812","article-title":"Monocyte chemoattractant protein-1 (MCP-1), not MCP-3, is the primary chemokine required for monocyte recruitment in mouse peritonitis induced with thioglycollate or zymosan A","volume":"183","author":"M Takahashi","year":"2009","journal-title":"J Immunol"},{"issue":"5106","key":"pone.0316967.ref051","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1126\/science.7682337","article-title":"Preferential migration of activated CD4 and CD8 T cells in response to MIP-1\u03b1 and MIP-1\u03b2","volume":"260","author":"DD Taub","year":"1993","journal-title":"Science"},{"issue":"1","key":"pone.0316967.ref052","doi-asserted-by":"crossref","first-page":"21697","DOI":"10.1038\/s41598-020-78710-7","article-title":"Increased interleukin-6 and macrophage chemoattractant protein-1 are associated with respiratory failure in COVID-19","volume":"10","author":"M J\u00f8ntvedt J\u00f8rgensen","year":"2020","journal-title":"Sci Rep"},{"issue":"1","key":"pone.0316967.ref053","first-page":"1","article-title":"Temporal profiling of plasma cytokines, chemokines and growth factors from mild, severe and fatal COVID-19 patients","volume":"5","author":"ZS Xu","year":"2020","journal-title":"Signal Transduct Target Ther"},{"issue":"10","key":"pone.0316967.ref054","doi-asserted-by":"crossref","first-page":"5010","DOI":"10.4049\/jimmunol.164.10.5010","article-title":"Cutting edge: stromal cell-derived factor-1 is a costimulator for CD4+ T cell activation","volume":"164","author":"T Nanki","year":"2000","journal-title":"J Immunol"},{"key":"pone.0316967.ref055","doi-asserted-by":"crossref","unstructured":"Aiuti A, Webb IJ, Bleul C, Springer T, Gutierrez-Ramos JC. The chemokine SDF-1 is a chemoattractant for human CD34+ hematopoietic progenitor cells and provides a new mechanism to explain the mobilization of CD34+ progenitors to peripheral blood. 1997.","DOI":"10.1084\/jem.185.1.111"},{"issue":"3","key":"pone.0316967.ref056","doi-asserted-by":"crossref","first-page":"1101","DOI":"10.1084\/jem.184.3.1101","article-title":"A highly efficacious lymphocyte chemoattractant, stromal cell-derived factor 1 (SDF-1)","volume":"184","author":"CC Bleul","year":"1996","journal-title":"J Exp Med"},{"key":"pone.0316967.ref057","doi-asserted-by":"crossref","first-page":"702","DOI":"10.1186\/s12879-023-08691-1","article-title":"Genetic clues to COVID-19 severity: exploring the stromal cell-derived factor-1\/CXCL12 rs2839693 polymorphism in adult Egyptians","volume":"23","author":"OH Korayem","year":"2023","journal-title":"BMC Infect Dis"},{"issue":"7962","key":"pone.0316967.ref058","doi-asserted-by":"crossref","first-page":"764","DOI":"10.1038\/s41586-023-06034-3","article-title":"GWAS and meta-analysis identifies 49 genetic variants underlying critical COVID-19","volume":"617","author":"E Pairo-Castineira","year":"2023","journal-title":"Nature"},{"key":"pone.0316967.ref059","article-title":"Characterisation of the pro-inflammatory cytokine signature in severe COVID-19","author":"HC Hawerkamp","year":"2023","journal-title":"Front Immunol"},{"issue":"6","key":"pone.0316967.ref060","doi-asserted-by":"crossref","first-page":"257","DOI":"10.1089\/jir.2023.0029","article-title":"COVID-19 Severity Shifts the Cytokine Milieu Toward a Proinflammatory State in Egyptian Patients: A Cross-Sectional Study","volume":"43","author":"ML Salem","year":"2023","journal-title":"J Interferon Cytokine Res"},{"issue":"1","key":"pone.0316967.ref061","doi-asserted-by":"crossref","first-page":"14209","DOI":"10.1038\/s41598-025-98505-y","article-title":"Cytokine profiles dynamics in COVID-19 patients: a longitudinal analysis of disease severity and outcomes","volume":"15","author":"S Ghaffarpour","year":"2025","journal-title":"Sci Rep"},{"issue":"5","key":"pone.0316967.ref062","doi-asserted-by":"crossref","first-page":"559","DOI":"10.1002\/jlb.56.5.559","article-title":"Essential involvement of interleukin-8 (IL-8) in acute inflammation","volume":"56","author":"A Harada","year":"1994","journal-title":"J Leukoc Biol"},{"key":"pone.0316967.ref063","article-title":"Interleukin-18 and IL-18 Binding Protein","author":"C Dinarello","year":"2013","journal-title":"Front Immunol"},{"key":"pone.0316967.ref064","article-title":"Evidence for the biological modulation of IL-1 activity: The role of IL-1Ra","author":"JM Dayer","year":"2001","journal-title":"Clin Exp Rheumatol"},{"issue":"3","key":"pone.0316967.ref065","doi-asserted-by":"crossref","DOI":"10.1128\/CMR.00299-20","article-title":"Critical determinants of cytokine storm and type I interferon response in COVID-19 pathogenesis","volume":"34","author":"S Ramasamy","year":"2021","journal-title":"Clin Microbiol Rev"},{"issue":"12","key":"pone.0316967.ref066","doi-asserted-by":"crossref","first-page":"3020","DOI":"10.3201\/eid2712.211465","article-title":"SARS-CoV-2 Seroprevalence in a Rural and Urban Household Cohort during First and Second Waves of Infections, South Africa, July 2020\u2013March 2021","volume":"27","author":"J Kleynhans","year":"2021","journal-title":"Emerg Infect Dis"},{"key":"pone.0316967.ref067","doi-asserted-by":"crossref","first-page":"100880","DOI":"10.1016\/j.eclinm.2021.100880","article-title":"Prevalence of SARS-CoV-2 in urban and rural Ethiopia: randomized household serosurveys reveal level of spread during the first wave of the pandemic","volume":"35","author":"S Abdella","year":"2021","journal-title":"EClinicalMedicine"},{"issue":"4","key":"pone.0316967.ref068","doi-asserted-by":"crossref","first-page":"569","DOI":"10.1111\/imm.12335","article-title":"Changes in immunological profile as a function of urbanization and lifestyle","volume":"143","author":"M Mbow","year":"2014","journal-title":"Immunology"},{"issue":"1","key":"pone.0316967.ref069","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1186\/s40413-015-0071-2","article-title":"Effects of environment on human cytokine responses during childhood in the tropics: role of urban versus rural residence","volume":"8","author":"PJ Cooper","year":"2015","journal-title":"World Allergy Organ J"},{"key":"pone.0316967.ref070","doi-asserted-by":"crossref","first-page":"102132","DOI":"10.1016\/j.parint.2020.102132","article-title":"Urban-rural differences in immune responses to mycobacterial and tetanus vaccine antigens in a tropical setting: A role for helminths?","volume":"78","author":"J Kabagenyi","year":"2020","journal-title":"Parasitol Int"}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0316967","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,9,11]],"date-time":"2025-09-11T17:29:09Z","timestamp":1757611749000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0316967"}},"subtitle":[],"editor":[{"given":"Ewurama Dedea Ampadu","family":"Owusu","sequence":"first","affiliation":[],"role":[{"role":"editor","vocabulary":"crossref"}]}],"short-title":[],"issued":{"date-parts":[[2025,9,11]]},"references-count":70,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2025,9,11]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0316967","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,9,11]]}}}