title: Allergic diseases and asthma in relation to serum immunoglobulins and salivary immunoglobulin A in pre-school children: a follow-up community-based study.
abstract: BACKGROUND
  We have previously reported an association between low IgA and allergic manifestations in early childhood (0-2 years) and have now followed our cohort for an additional 2 years.
  
  
  OBJECTIVE
  To evaluate in a longitudinal community-based cohort study the association between maturation of Ig production and allergic manifestations in the first 4 years of life.
  
  
  METHODS
  A cohort of 161 randomly selected children was followed from birth to the age of 42-48 months and evaluated at 18-23 months (EV1; n = 179) and again at the age of 42-48 months (EV2; n = 161). Diagnoses were made with the help of a clinical questionnaire, physical examination and skin prick tests (SPTs) to 10 common allergens. Serum immunoglobulins were measured at EV1 and EV2, and salivary IgA (sal-IgA) at EV2.
  
  
  RESULTS
  Serum IgA, IgE, IgG1, IgG2 and IgG4 increased from 2 to 4 years of age (P < 0.001) and their levels showed close correlations (P < or = 0.01 for most comparisons). Children with one or more positive SPTs had lower serum IgA (P = 0.004) and IgG4 (P = 0.05) at EV2 than those who did not respond, and children who developed allergic rhinitis between EV1 and EV2 had low sal-IgA (P = 0.006) and IgG3 (P < 0.05) at EV2. Atopic eczema was associated with low sal-IgA at EV2, and children who developed eczema between EV1 and EV2 had significantly lower sal-IgA than those who recovered after EV1 (P = 0.02).
  
  
  CONCLUSIONS
  Allergic manifestations in predisposed children may be influenced by the rate of maturation of immunological components that counteract sensitization or inhibit effector mechanisms of allergy.
authors.affiliation: Department of Immunology, Institute of Laboratory Medicine, Landspítali University Hospital, Reykjavík, Iceland. bjornlud@landspitali.is
authors.forename: B R
authors.initials: BR
authors.lastname: Lúdvíksson
authors.forename: G J
authors.initials: GJ
authors.lastname: Arason
authors.forename: O
authors.initials: O
authors.lastname: Thorarensen
authors.forename: B
authors.initials: B
authors.lastname: Ardal
authors.forename: H
authors.initials: H
authors.lastname: Valdimarsson
mesh_terms: D001249:Asthma / Q000276:immunology*; D002675:Child, Preschool; D003876:Dermatitis, Atopic / Q000276:immunology; D005500:Follow-Up Studies; D006801:Humans; D006967:Hypersensitivity / Q000097:blood*; D007070:Immunoglobulin A / Q000032:analysis* / Q000097:blood; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007231:Infant, Newborn; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology; D012463:Saliva / Q000276:immunology*; D012882:Skin Tests; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007073:Immunoglobulin E