title: Preterm infants' T cell responses to inactivated poliovirus vaccine.
abstract: BACKGROUND
  The antigen-specific T cell responses of preterm infants to immunization are not well understood. The aim of the present study was to compare the T cell responses of preterm infants after inactivated poliovirus vaccination with those of term infants.
  
  
  METHODS
  We prospectively enrolled 2-month-old preterm (gestational age, 33 weeks) and term (gestational age, 37 weeks) infants to receive 3 doses of diphtheria-tetanus toxoids-acellular pertussis-hepatitis B virus-inactivated poliovirus vaccine. Whole blood and peripheral blood mononuclear cells (PBMCs) were stimulated with poliovirus vaccine, and memory T cell activation was analyzed by flow cytometry and lymphoproliferation, respectively. Levels of poliovirus neutralizing antibodies were measured in serum.
  
  
  RESULTS
  We enrolled 33 preterm and 50 term infants. Preterm infants had fewer circulating CD4(+)CD45RO(+) memory (P = .005) and CD4(+)CD69(+)IFN-gamma(+) cells activated by staphylococcus enterotoxin B at 2 (P = .015) and 7 (P = .05) months of age. After immunization, preterm and term infants had comparable frequencies of poliovirus-specific CD4(+)CD45RO(+)CD69(+)IFN-gamma(+) memory T cells (P = .79). PBMCs from preterm infants had diminished poliovirus-specific lymphoproliferation (P<.001). Although all infants developed seroprotective poliovirus antibody titers, serotype 1 titers were lower among preterm infants (P = .03).
  
  
  CONCLUSIONS
  Preterm infants develop poliovirus-specific T cell responses that are comparable to those of term infants. However, they demonstrate nonspecific and poliovirus-specific functional T cell limitations, suggesting that investigations into whether T cell differences remain as preterm infants mature are warranted.
authors.affiliation: Kaiser Permanente Vaccine Study Center, Oakland, California 94612, USA. Nicola.Klein@kp.org
authors.forename: Nicola P
authors.initials: NP
authors.lastname: Klein
authors.forename: Hayley A
authors.initials: HA
authors.lastname: Gans
authors.forename: Phillip
authors.initials: P
authors.lastname: Sung
authors.forename: Linda L
authors.initials: LL
authors.lastname: Yasukawa
authors.forename: Joanie
authors.initials: J
authors.lastname: Johnson
authors.forename: Andrey
authors.initials: A
authors.lastname: Sarafanov
authors.forename: Konstantin
authors.initials: K
authors.lastname: Chumakov
authors.forename: John
authors.initials: J
authors.lastname: Hansen
authors.forename: Steven
authors.initials: S
authors.lastname: Black
authors.forename: Cornelia L
authors.initials: CL
authors.lastname: Dekker
mesh_terms: D000914:Antibodies, Viral / Q000097:blood; D016022:Case-Control Studies; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007111:Immunity, Cellular; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000276:immunology*; D008297:Male; D009000:Monocytes / Q000276:immunology; D011054:Poliovirus Vaccine, Inactivated / Q000276:immunology*; D011446:Prospective Studies; D013601:T-Lymphocytes / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D011054:Poliovirus Vaccine, Inactivated; D018074:Vaccines, Conjugate