title: Immune response to measles vaccine in Peruvian children.
abstract: OBJECTIVE
  To evaluate the immune response in Peruvian children following measles vaccination.
  
  
  METHODS
  Fifty-five Peruvian children received Schwarz measles vaccine (about 10(3) plaque forming units) at about 9 months of age. Blood samples were taken before vaccination, then twice after vaccination: one sample at between 1 and 4 weeks after vaccination and the final sample 3 months post vaccination for evaluation of immune cell phenotype and lymphoproliferative responses to measles and non-measles antigens. Measles-specific antibodies were measured by plaque reduction neutralization.
  
  
  RESULTS
  The humoral response developed rapidly after vaccination; only 4 of the 55 children (7%) had plaque reduction neutralization titres <200 mlU/ml 3 months after vaccination. However, only 8 out of 35 children tested (23%) had lymphoproliferative responses to measles antigens 3-4 weeks after vaccination. Children with poor lymphoproliferative responses to measles antigens had readily detectable lymphoproliferative responses to other antigens. Flow cytometric analysis of peripheral blood mononuclear cells revealed diffuse immune system activation at the time of vaccination in most children. The capacity to mount a lymphoproliferative response to measles antigens was associated with expression of CD45RO on CD4+ T-cells.
  
  
  CONCLUSIONS
  The 55 Peruvian children had excellent antibody responses after measles vaccination, but only 23% (8 out of 35) generated detectable lymphoproliferative responses to measles antigens (compared with 55-67% in children in the industrialized world). This difference may contribute to the less than uniform success of measles vaccination programmes in the developing world.
authors.affiliation: McGil University Department of Parasitology, Montreal, Quebec, Canada.
authors.forename: N L
authors.initials: NL
authors.lastname: Bautista-López
authors.forename: A
authors.initials: A
authors.lastname: Vaisberg
authors.forename: R
authors.initials: R
authors.lastname: Kanashiro
authors.forename: H
authors.initials: H
authors.lastname: Hernández
authors.forename: B J
authors.initials: BJ
authors.lastname: Ward
mesh_terms: D000914:Antibodies, Viral / Q000096:biosynthesis / Q000097:blood*; D000917:Antibody Formation / Q000187:drug effects / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007223:Infant; D008213:Lymphocyte Activation; D008297:Male; D008458:Measles Vaccine / Q000276:immunology*; D008459:Measles virus / Q000276:immunology; D009000:Monocytes / Q000166:cytology / Q000276:immunology*; D009500:Neutralization Tests; D010568:Peru; D010641:Phenotype
chemical_list: D000914:Antibodies, Viral; D008458:Measles Vaccine