title: Cellular immunity is activated and a TH-2 response is associated with early wheezing in infants after bronchiolitis.
abstract: OBJECTIVE
  To determine whether abnormalities of cellular immunity are present and linked to early wheezing after bronchiolitis.
  
  
  METHODS
  We prospectively studied 26 infants hospitalized for a first episode of bronchiolitis and without any prior immune, cardiac, or respiratory disease. Blood was obtained at the time of enrollment and 5 months later for the assessment of the total cellular and differential counts, CD4+ (helper) and CD8+ (suppressor/cytotoxic) lymphocytes, and the activation markers CD23 (low-affinity immunoglobulin E receptor) and CD25 (interleukin-2 (IL-2) receptor). The cytokines interferon gamma (T-helper (TH) type-1 cytokine) and IL-4 (TH-2) were measured in plasma and in vitro after stimulation with IL-2 or with the house-dust mite (Dermatophagoides farinae) antigen. A daily log of episodes of wheezing was kept by parents after discharge.
  
  
  RESULTS
  We found an increase in blood eosinophils, an increased percentage of CD4+, CD25+, and CD23+ lymphocytes in subjects at 5 months compared with the time of bronchiolitis and with healthy subjects of the same age (p < 0.05). Plasma IL-4 levels, although not different from those of healthy subjects, also increased significantly. Peripheral blood lymphocytes from infants who wheezed produced more IL-4 in vitro, 5 months after bronchiolitis, in response to D. farinae antigen. In babies who wheezed, a positive correlation was found between the total number of days that wheezing occurred and the blood eosinophil count. Babies who wheezed more often (> 20 days) had more peripheral blood basophils and eosinophils, and peripheral blood lymphocytes obtained from these subjects at the time of bronchiolitis produced less interferon gamma on stimulation with IL-2.
  
  
  CONCLUSIONS
  Bronchiolitis is followed by activation of cellular immunity, and early wheezing in infants is associated with a TH-2 response.
authors.affiliation: Sainte-Justine, Research Center, University of Montreal, Quebec, Canada.
authors.forename: P M
authors.initials: PM
authors.lastname: Renzi
authors.forename: J P
authors.initials: JP
authors.lastname: Turgeon
authors.forename: J P
authors.initials: JP
authors.lastname: Yang
authors.forename: S P
authors.initials: SP
authors.lastname: Drblik
authors.forename: J E
authors.initials: JE
authors.lastname: Marcotte
authors.forename: L
authors.initials: L
authors.lastname: Pedneault
authors.forename: S
authors.initials: S
authors.lastname: Spier
mesh_terms: D000208:Acute Disease; D000485:Allergens / Q000276:immunology; D000818:Animals; D001990:Bronchiolitis, Viral / Q000097:blood / Q000150:complications / Q000276:immunology*; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007223:Infant; D007371:Interferon-gamma / Q000378:metabolism; D015847:Interleukin-4 / Q000097:blood*; D007958:Leukocyte Count; D008213:Lymphocyte Activation; D016131:Lymphocyte Subsets; D008297:Male; D008925:Mites; D011446:Prospective Studies; D012135:Respiratory Sounds / Q000209:etiology*; D006377:T-Lymphocytes, Helper-Inducer / Q000378:metabolism*
chemical_list: D000485:Allergens; D015847:Interleukin-4; D007073:Immunoglobulin E; D007371:Interferon-gamma