title: Antibiotic use during infancy promotes a shift in the T(H)1/T(H)2 balance toward T(H)2-dominant immunity in mice.
abstract: BACKGROUND
  Recent epidemiologic studies indicate that antibiotic use in infancy may be associated with an increased risk of development of atopy; however, its precise mechanism remains to be elucidated.
  
  
  OBJECTIVE
  The purpose of this study is to clarify whether one such antibiotic, kanamycin, affects the T(H)1/T(H)2 balance.
  
  
  METHODS
  BALB/c mice at 3 and 52 weeks of age were orally administered 600 mg/d kanamycin sulfate for 7 consecutive days. Blood samples were collected on weeks 0, 10, 18, and 26 after the cessation of kanamycin treatment, and the effect of the kanamycin treatment on the T(H)1/T(H)2 balance was evaluated on the basis of both the in vivo antibody levels and the in vitro splenocyte cytokine secretion pattern.
  
  
  RESULTS
  The administration of kanamycin increased the serum levels of total IgG1 and IgE while decreasing the serum IgG2a levels. Moreover, when spleen cells were stimulated with immobilized anti-CD3 antibody in vitro, such kanamycin treatment enhanced the in vitro IL-4 secretion while reducing the in vitro IFN-gamma secretion. The basal IL-12 p70 secretion levels of splenic dendritic cells in the kanamycin-treated mice were lower than those in the control mice, although no significant difference was seen in IL-12 p40 levels between either group of mice.
  
  
  CONCLUSIONS
  These results suggested that antibiotic use during infancy may indeed quantitatively disturb, qualitatively disturb, or both the intestinal microflora and thereby prevent postnatal T(H)1 cell maturation, thus resulting in a T(H)2-polarized immune deviation.
authors.affiliation: Department of Psychosomatic Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Oyama
authors.forename: N
authors.initials: N
authors.lastname: Sudo
authors.forename: H
authors.initials: H
authors.lastname: Sogawa
authors.forename: C
authors.initials: C
authors.lastname: Kubo
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D000906:Antibodies / Q000097:blood; D016207:Cytokines / Q000096:biosynthesis; D003713:Dendritic Cells / Q000378:metabolism; D003864:Depression, Chemical; D007109:Immunity / Q000187:drug effects; D018664:Interleukin-12 / Q000096:biosynthesis; D007612:Kanamycin / Q000627:therapeutic use*; D018655:Lymphocyte Count; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010581:Peyer's Patches / Q000166:cytology; D013154:Spleen / Q000166:cytology / Q000378:metabolism; D018417:Th1 Cells / Q000187:drug effects* / Q000502:physiology*; D018418:Th2 Cells / Q000187:drug effects* / Q000276:immunology*
chemical_list: D000900:Anti-Bacterial Agents; D000906:Antibodies; D016207:Cytokines; D018664:Interleukin-12; D007612:Kanamycin