title: Evaluation of serological tests detecting Chlamydophila pneumoniae-specific immunoglobulin M antibody.
abstract: OBJECTIVE
  To evaluate a newly developed enzyme-linked immunosorbent assay (ELISA) (Hitazyme C. pneumoniae) detecting Chlamydophila pneumoniae-specific immunoglobulin M (IgM) antibody, we compared the assay with culturing, immunoblotting and the microimmunofluorescence (MIF) test.
  
  
  METHODS
  Two hundred five patients with stable chronic lung diseases without acute respiratory tract infections (ARTIs) and 116 healthy volunteers without ARTIs were enrolled in this study. Nasopharyngeal swab specimens and sera were obtained from all subjects for isolation and serological testing of C. pneumoniae.
  
  
  RESULTS
  C. pneumoniae IgM-positive results were observed in 16.5% of patients with stable chronic lung diseases and in 8.6% of asymptomatic healthy subjects. However, there were no positive cases with cell culture, immunoblot or MIF test. In addition, no cases with a significant increase in IgA or IgG antibody titer for the ELISA kit and MIF test between paired sera were observed in the followed-up groups. IgM-positive cases were more frequent among patients with chronic obstructive pulmonary disease (p=0.1566), collagen disease-associated interstitial lung disease (p<0.0001) and cryptogenic organizing pneumonia (p=0.0199) than among the healthy subjects.
  
  
  CONCLUSIONS
  Our results indicate that IgM-positive results with the ELISA kit do not always reflect acute C. pneumoniae infections. Further studies are needed, to determine an appropriate cut-off level and the possible causes of the false-positive results in the ELISA kit, such as other underlying conditions.
authors.affiliation: Division of Respiratory Diseases, Department of Medicine, Kawasaki Medical School, Okayama.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Miyashita
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Obase
authors.forename: Minoru
authors.initials: M
authors.lastname: Fukuda
authors.forename: Hisashi
authors.initials: H
authors.lastname: Shoji
authors.forename: Keiji
authors.initials: K
authors.lastname: Mouri
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yagi
authors.forename: Koichiro
authors.initials: K
authors.lastname: Yoshida
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Ouchi
authors.forename: Mikio
authors.initials: M
authors.lastname: Oka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood* / Q000276:immunology; D001327:Autoimmune Diseases / Q000276:immunology; D002478:Cells, Cultured / Q000382:microbiology; D023521:Chlamydophila Infections / Q000175:diagnosis* / Q000276:immunology; D016993:Chlamydophila pneumoniae / Q000254:growth & development / Q000276:immunology* / Q000302:isolation & purification; D003095:Collagen Diseases / Q000276:immunology; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D005189:False Positive Reactions; D005260:Female; D005455:Fluorescent Antibody Technique; D005500:Follow-Up Studies; D006801:Humans; D015151:Immunoblotting; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood* / Q000276:immunology; D008171:Lung Diseases / Q000276:immunology*; D017563:Lung Diseases, Interstitial / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009305:Nasopharynx / Q000382:microbiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M