title: Effects of severe acute respiratory syndrome (SARS) coronavirus infection on peripheral blood lymphocytes and their subsets.
abstract: BACKGROUND
  Severe acute respiratory syndrome (SARS) caused large outbreaks of atypical pneumonia in 2003, with the largest localized outbreak occurring in Beijing, China. Lymphopenia was prominent amongst the laboratory abnormalities reported in acute SARS.
  
  
  METHODS
  The effect of SARS on peripheral blood lymphocytes and their subsets was examined in 271 SARS coronavirus-infected individuals.
  
  
  RESULTS
  There was a significant decrease in the CD45+, CD3+, CD4+, CD8+, CD19+ and CD16+/56+ cell counts over the five weeks of the SARS illness although CD4+/CD8+ ratios did not change significantly. The lymphopenia was prolonged, reaching a nadir during days 7-9 in the second week of illness before returning towards normal after five weeks, with the lowest mean CD4+ cell count of 317 cellsx10(6)/L at day 7, and CD8+ cell count of 239 cellsx10(6)/L at day 8. Patients with more severe clinical illness, or patients who died, had significantly more profound CD4+ and CD8+ lymphopenia.
  
  
  CONCLUSIONS
  Lymphopenia is a prominent part of SARS-CoV infection and lymphocyte counts may be useful in predicting the severity and clinical outcomes. Possible reasons for the SARS-associated lymphopenia may be direct infection of lymphocytes by SARS-CoV, lymphocyte sequestration in the lung or cytokine-mediated lymphocyte trafficking. There may also be immune-mediated lymphocyte destruction, bone marrow or thymus suppression, or apoptosis.
authors.affiliation: Capital University of Medical Sciences Affiliated Beijing YouAn Hospital, Beijing 100054, PR China. zhongpinghe@yahoo.com
authors.forename: Zhongping
authors.initials: Z
authors.lastname: He
authors.forename: Chunhui
authors.initials: C
authors.lastname: Zhao
authors.forename: Qingming
authors.initials: Q
authors.lastname: Dong
authors.forename: Hui
authors.initials: H
authors.lastname: Zhuang
authors.forename: Shujing
authors.initials: S
authors.lastname: Song
authors.forename: Guoai
authors.initials: G
authors.lastname: Peng
authors.forename: Dominic E
authors.initials: DE
authors.lastname: Dwyer
mesh_terms: D000293:Adolescent; D000328:Adult; D018941:Antigens, CD19 / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D015704:CD4 Antigens / Q000378:metabolism; D016516:CD4-CD8 Ratio; D016827:CD8 Antigens / Q000378:metabolism; D005260:Female; D006801:Humans; D017493:Leukocyte Common Antigens / Q000378:metabolism; D008213:Lymphocyte Activation; D018655:Lymphocyte Count; D016131:Lymphocyte Subsets / Q000276:immunology*; D008231:Lymphopenia; D008297:Male; D008875:Middle Aged; D017452:Receptors, IgG / Q000378:metabolism; D045473:Severe acute respiratory syndrome-related coronavirus / Q000472:pathogenicity*; D045169:Severe Acute Respiratory Syndrome / Q000276:immunology* / Q000503:physiopathology*
chemical_list: D018941:Antigens, CD19; D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D017452:Receptors, IgG; D017493:Leukocyte Common Antigens