title: An in vitro method to investigate the microbicidal potential of human macrophages for use in psychosomatic research.
abstract: OBJECTIVE
  Psychological states relate to changes in circulating immune cells, but associations with immune cells in peripheral tissues such as macrophages have hardly been investigated. Here, we aimed to implement and validate a method for measuring the microbicidal potential of ex vivo isolated human monocyte-derived macrophages (HMDMs) as an indicator of macrophage activation.
  
  
  METHODS
  The method was implemented and validated for two blood sampling procedures (short-term cannula insertion versus long-term catheter insertion) in 79 participants (34 women, 45 men) aged between 18 and 75 years. The method principle is based on the reduction of 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-dis-ulfophenyl)-2H-tetrazolium, monosodium salt (WST-1) by superoxide anions, the first in a series of pathogen-killing reactive oxygen species produced by phorbol myristate acetate-activated HMDM. Cytochrome c reduction and current generation were measured as reference methods for validation purposes. We further evaluated whether depressive symptom severity (Beck Depression Inventory) and chronic stress (Chronic Stress Screening Scale) were associated with macrophage microbicidal potential.
  
  
  RESULTS
  The assay induced superoxide anion responses by HMDM in all participants. Assay results depended on blood sampling procedure (cannula versus catheter insertion). Interassay variability as a measure for assay reliability was 10.92% or less. WST-1 reduction scores correlated strongly with results obtained by reference methods (cytochrome c: r = 0.57, p = .026; current generation: r values ≥ 0.47, p values <.033) and with psychological factors (depressive symptom severity: r = 0.35 [cannula insertion] versus r = -0.54 [catheter insertion]; chronic stress: r = 0.36 [cannula insertion]; p values ≤ .047).
  
  
  CONCLUSIONS
  Our findings suggest that the implemented in vitro method investigates microbicidal potential of HMDM in a manner that is valid and sensitive to psychological measures.
authors.affiliation: Department of Psychology, Biological and Health Psychology, University of Bern, Alpeneggstrasse 22, 3012 Bern, Switzerland. petra.wirtz@psy.unibe.ch.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Kuebler
authors.forename: Ulrike
authors.initials: U
authors.lastname: Ehlert
authors.forename: Claudia
authors.initials: C
authors.lastname: Zuccarella
authors.forename: Miho
authors.initials: M
authors.lastname: Sakai
authors.forename: Andreas
authors.initials: A
authors.lastname: Stemmer
authors.forename: Petra H
authors.initials: PH
authors.lastname: Wirtz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002406:Catheterization, Peripheral / Q000379:methods; D002460:Cell Line; D002908:Chronic Disease; D003863:Depression / Q000276:immunology*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011569:Psychiatric Status Rating Scales; D011611:Psychosomatic Medicine; D017382:Reactive Oxygen Species / Q000097:blood; D015203:Reproducibility of Results; D012107:Research Design; D012720:Severity of Illness Index; D013048:Specimen Handling / Q000379:methods; D013315:Stress, Psychological / Q000276:immunology*; D013481:Superoxides / Q000097:blood; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013778:Tetrazolium Salts; D055815:Young Adult
chemical_list: C110656:2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium; D007202:Indicators and Reagents; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013481:Superoxides; D013755:Tetradecanoylphorbol Acetate
keywords: chronic stress; depressive mood; human macrophages; in vitro method; microbicidal potential; reactive oxygen species