title: CD4+/CD8+ T lymphocytes imbalance in children with severe 2009 pandemic influenza A (H1N1) pneumonia.
abstract: OBJECTIVE
  This study was conducted to investigate the immune responses of children with moderate and severe novel influenza A virus (H1N1) pneumonia, and to compare their clinical and immunological findings with those of control subjects.
  
  
  METHODS
  Thirty-two admitted patients with H1N1 pneumonia were enrolled in the study. The clinical profiles, humoral and cell-mediated immune responses of the 16 H1N1 pneumonia patients who were admitted to the pediatric intensive care unit (severe pneumonia group), 16 H1N1 pneumonia patients admitted to the pediatric general ward (moderate pneumonia group) and 13 control subjects (control group) were measured.
  
  
  RESULTS
  Total lymphocyte counts were significantly lower in patients with H1N1 pneumonia than in the control group (P=0.02). The number of CD4+ T lymphocytes was significantly lower in the severe pneumonia group (411.5±253.5/µL) than in the moderate pneumonia (644.9±291.1/µL, P=0.04) and control (902.5±461.2/µL, P=0.01) groups. However, the number of CD8+ T lymphocytes was significantly higher in the severe pneumonia group (684.2±420.8/µL) than in the moderate pneumonia (319.7±176.6/µL, P=0.02) and control (407.2±309.3/µL, P=0.03) groups. The CD4+/CD8+ T lymphocytes ratio was significantly lower in the severe pneumonia group (0.86±0.24) than in the moderate pneumonia (1.57±0.41, P=0.01) and control (1.61±0.49, P=0.01) groups. The serum levels of IgG, IgM and IgE were significantly higher in the severe pneumonia group than in the 2 other groups.
  
  
  CONCLUSIONS
  The results of this study suggest that increased humoral immune responses and the differences in the CD4+ and CD8+ T lymphocyte profiles, and imbalance of their ratios may be related to the severity of H1N1 pneumonia in children.
authors.affiliation: Department of Pediatrics, Korea University Anam Hospital, Seoul, Korea.
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Kim
authors.forename: Siegfried
authors.initials: S
authors.lastname: Bauer
authors.forename: Kyong Suk
authors.initials: KS
authors.lastname: La
authors.forename: Kee Hyoung
authors.initials: KH
authors.lastname: Lee
authors.forename: Ji Tae
authors.initials: JT
authors.lastname: Choung
authors.forename: Kyoung Ho
authors.initials: KH
authors.lastname: Roh
authors.forename: Chang Kyu
authors.initials: CK
authors.lastname: Lee
authors.forename: Young
authors.initials: Y
authors.lastname: Yoo