title: Long-term T-cell-mediated immunologic memory to hepatitis B vaccine in young adults following neonatal vaccination.
abstract: BACKGROUND
  The long-term duration of cell-mediated immunity induced by neonatal hepatitis B virus (HBV) vaccination is unknown.
  
  
  OBJECTIVE
  Study was designed to determine the cellular immunity memory status among young adults twenty years after infantile HB immunization.
  
  
  METHODS
  Study subjects were party selected from a recent seroepidemiologic study in young adults, who had been vaccinated against HBV twenty years earlier. Just before and ten to 14 days after one dose of HBV vaccine booster injection, blood samples were obtained and sera concentration of cytokines (interleukin 2 and interferon) was measured. More than twofold increase after boosting was considered positive immune response. With regard to the serum level of antibody against HBV surface antigen (HBsAb) before boosting, the subjects were divided into four groups as follow: GI, HBsAb titer < 2; GII, titer 2 to 9.9; GIII, titer 10 to 99; and GIV, titers ≥ 100 IU/L. Mean concentration level (MCL) of each cytokines for each group at preboosting and postboosting and the proportion of responders in each groups were determined. Paired descriptive statistical analysis method (t test) was used to compare the MCL of each cytokines in each and between groups and the frequency of responders in each group.
  
  
  RESULTS
  Before boosting, among 176 boosted individuals, 75 (42.6%) had HBsAb 10 IU/L and were considered seroprotected. Among 101 serosusceptible persons, more than 80% of boosted individuals showed more than twofold increase in cytokines concentration, which meant positive HBsAg-specific cell-mediated immunity. MCL of both cytokines after boosting in GIV were decreased more than twofold, possibly because of recent natural boosting.
  
  
  CONCLUSIONS
  Findings showed that neonatal HBV immunization was efficacious in inducing long-term immunity and cell-mediated immune memory for up to two decades, and booster vaccination are not required. Further monitoring of vaccinated subjects for HBV infections are recommended.
authors.affiliation: Department of Pathology, Shariaty Hospital, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Hiva
authors.initials: H
authors.lastname: Saffar
authors.affiliation: Department of Pediatric Infectious Diseases Ward, Boali-Sina Hospital and Antimicrobial Resistant Nosocomial Infection Research Center, Mazandaran University of Medical Sciences, Sari, IR Iran.
authors.forename: Mohammed Jafar
authors.initials: MJ
authors.lastname: Saffar
authors.affiliation: Molecular and Cell-Biology Research Center, School of Medicine, Mazandaran University of Medical Sciences, Sari, IR Iran.
authors.forename: Abolghasem
authors.initials: A
authors.lastname: Ajami
authors.affiliation: Department of Biostatistics, Mazandaran University of Medical Sciences, Sari, IR Iran.
authors.forename: Ali Reza
authors.initials: AR
authors.lastname: Khalilian
authors.affiliation: Department of Pathology, Shariaty Hospital, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Kian
authors.initials: K
authors.lastname: Shams-Esfandabad
authors.affiliation: Molecular and Cell-Biology Research Center, School of Medicine, Mazandaran University of Medical Sciences, Sari, IR Iran.
authors.forename: Araz Mohammad
authors.initials: AM
authors.lastname: Mirabi
keywords: Booster Vaccination; Cell-Mediated Immunity; Hepatitis B Vaccine