title: Antibody responses of Chlamydophila pneumoniae pneumonia: Why is the diagnosis of C. pneumoniae pneumonia difficult?
abstract: The ELNAS Plate Chlamydophila pneumoniae commercial test kit for the detection of anti-C. pneumoniae-specific immunoglobulin M (IgM), IgA and IgG antibodies has become available in Japan recently. To determine the optimum serum collection point for the ELNAS plate in the diagnosis of C. pneumoniae pneumonia, we analyzed the kinetics of the antibody response in patients with laboratory-confirmed C. pneumoniae pneumonia. We enrolled five C. pneumoniae pneumonia cases and collected sera from patients for several months. The kinetics of the IgM and IgG antibody responses were similar among the five patients. Significant increases in IgM and IgG antibody titer between paired sera were observed in all patients. IgM antibodies appeared approximately 2-3 weeks after the onset of illness, reached a peak after 4-5 weeks, and were generally undetectable after 3-5 months. IgG antibodies developed slowly for the first 30 days and reached a plateau approximately 3-4 months after the onset of illness. The kinetics of IgA antibody responses were different among the five patients, and significant increases in IgA antibody titer between paired sera were observed in only two patients. Although the sample size was small, the best serum collection time seemed to be approximately 3-6 weeks after onset of illness when using a single serum sample for the detection of IgM antibodies. Paired sera samples should be obtained at least 4 weeks apart. IgA antibody analysis using ELNAS may not be a useful marker for acute C. pneumoniae pneumonia.
authors.affiliation: Department of Internal Medicine I, Kawasaki Medical School, Okayama, Japan. Electronic address: nao@med.kawasaki-m.ac.jp.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Miyashita
authors.affiliation: Department of Internal Medicine I, Kawasaki Medical School, Okayama, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kawai
authors.affiliation: Department of Pediatrics, Kawasaki Medical School, Okayama, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Pediatrics, Kawasaki Medical School, Okayama, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Akaike
authors.affiliation: Department of Pediatrics, Kawasaki Medical School, Okayama, Japan.
authors.forename: Hideto
authors.initials: H
authors.lastname: Teranishi
authors.affiliation: Department of Pediatrics, Kawasaki Medical School, Okayama, Japan.
authors.forename: Tokio
authors.initials: T
authors.lastname: Wakabayashi
authors.affiliation: Department of Pediatrics, Kawasaki Medical School, Okayama, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
authors.affiliation: Department of Pediatrics, Kawasaki Medical School, Okayama, Japan.
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Ouchi
authors.affiliation: Department of Internal Medicine I, Kawasaki Medical School, Okayama, Japan.
authors.forename: Niro
authors.initials: N
authors.lastname: Okimoto
mesh_terms: D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood*; D023521:Chlamydophila Infections / Q000175:diagnosis* / Q000276:immunology* / Q000382:microbiology; D016993:Chlamydophila pneumoniae / Q000276:immunology*; D005260:Female; D006801:Humans; D007136:Immunoglobulins / Q000097:blood; D007564:Japan; D008297:Male; D018410:Pneumonia, Bacterial / Q000175:diagnosis* / Q000276:immunology* / Q000382:microbiology; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D007136:Immunoglobulins
keywords: Antibody response; Chlamydophila pneumoniae; ELNAS plate; Immunoglobulin A; Immunoglobulin G; Immunoglobulin M