title: Simultaneous quantitative analysis of the expression of CD64 and CD35 on neutrophils as markers to differentiate between bacterial and viral infections in patients with rheumatoid arthritis.
abstract: OBJECTIVE
  The expression level of CD64 on neutrophils can be used to differentiate between an infection and a disease flare in rheumatoid arthritis (RA) patients. However, the CD64 expression is elevated by both bacteria and viruses, so it cannot be used to distinguish the type of infection. We herein investigated the results of a simultaneous quantitative analysis of the expression of CD64 and CD35 on neutrophils to determine whether these molecules can be used to distinguish between bacterial and viral infections in RA patients.
  
  
  METHODS
  We collected blood from 22 RA patients with pathogen-proven infections (15 bacterial and 7 viral infections). Blood samples were stained with QuantiBRITE CD64PE/CD45PerCP and CD35PE, and the mean fluorescence intensities were assessed by a flow cytometer. The mean numbers of molecules were calculated using QuantiBrite PE beads.
  
  
  RESULTS
  We calculated the ratio of CD64 to the CD35 level (CD35/CD64), and used a cut-off value of 2.8 for the CD35/CD64 ratio. At this value, the sensitivity for diagnosing a bacterial infection was 87%, and the specificity was 86%.
  
  
  CONCLUSIONS
  Simultaneous quantitative analysis of CD64 and CD35 expression on neutrophils might be useful to distinguish between bacterial and viral infections in RA patients.
authors.affiliation: Department of Internal Medicine, Center for Rheumatic Diseases, Dohgo Spa Hospital, 21-21 Otsu Dohgo-Himezuka, Matsuyama, Ehime 790-0858, Japan. bachblau_since2001@yahoo.co.jp
authors.forename: Sho
authors.initials: S
authors.lastname: Mokuda
authors.forename: Osamu
authors.initials: O
authors.lastname: Doi
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takasugi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000276:immunology / Q000473:pathology*; D001424:Bacterial Infections / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000276:immunology*; D011237:Predictive Value of Tests; D017463:Receptors, Complement 3b / Q000097:blood*; D017452:Receptors, IgG / Q000097:blood*; D014777:Virus Diseases / Q000150:complications / Q000175:diagnosis* / Q000276:immunology
chemical_list: D015415:Biomarkers; C509991:CR1 protein, human; D017463:Receptors, Complement 3b; D017452:Receptors, IgG