title: Switched memory B cells maintain specific memory independently of serum antibodies: the hepatitis B example.
abstract: The immunogenicity of a vaccine is conventionally measured through the level of serum Abs early after immunization, but to ensure protection specific Abs should be maintained long after primary vaccination. For hepatitis B, protective levels often decline over time, but breakthrough infections do not seem to occur. The aim of this study was to demonstrate whether, after hepatitis B vaccination, B-cell memory persists even when serum Abs decline. We compared the frequency of anti-hepatitis-specific memory B cells that remain in the blood of 99 children five years after priming with Infanrix -hexa (GlaxoSmithKline) (n=34) or with Hexavac (Sanofi Pasteur MSD) (n=65). These two vaccines differ in their ability to generate protective levels of IgG. Children with serum Abs under the protective level, <10 mIU/mL, received a booster dose of hepatitis B vaccine, and memory B cells and serum Abs were measured 2 wk later. We found that specific memory B cells had a similar frequency in all children independently of primary vaccine. Booster injection resulted in the increase of memory B cell frequencies (from 11.3 in 10(6) cells to 28.2 in 10(6) cells, p<0.01) and serum Abs (geometric mean concentration, GMC from 2.9 to 284 mIU/mL), demonstrating that circulating memory B cells effectively respond to Ag challenge even when specific Abs fall under the protective threshold.
authors.affiliation: Research Center Ospedale Pediatrico Bambino Gesù, IRCSS, Laboratory of Flow-Cytometry and B Cell Development, Rome, Italy.
authors.forename: M Manuela
authors.initials: MM
authors.lastname: Rosado
authors.forename: Marco
authors.initials: M
authors.lastname: Scarsella
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Pandolfi
authors.forename: Simona
authors.initials: S
authors.lastname: Cascioli
authors.forename: Ezio
authors.initials: E
authors.lastname: Giorda
authors.forename: Paola
authors.initials: P
authors.lastname: Chionne
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Madonne
authors.forename: Francesco
authors.initials: F
authors.lastname: Gesualdo
authors.forename: Mariateresa
authors.initials: M
authors.lastname: Romano
authors.forename: Clara M
authors.initials: CM
authors.lastname: Ausiello
authors.forename: Maria
authors.initials: M
authors.lastname: Rapicetta
authors.forename: Alessandro R
authors.initials: AR
authors.lastname: Zanetti
authors.forename: Alberto
authors.initials: A
authors.lastname: Tozzi
authors.forename: Rita
authors.initials: R
authors.lastname: Carsetti
mesh_terms: D016175:B-Lymphocyte Subsets / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D002452:Cell Count; D002648:Child; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000008:administration & dosage; D005260:Female; D018073:Haemophilus Vaccines / Q000008:administration & dosage; D006509:Hepatitis B / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D006510:Hepatitis B Antibodies / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics; D017325:Hepatitis B Vaccines / Q000008:administration & dosage; D006515:Hepatitis B virus / Q000276:immunology*; D006801:Humans; D007115:Immunization Schedule; D007156:Immunologic Memory / Q000187:drug effects / Q000276:immunology; D008297:Male; D011054:Poliovirus Vaccine, Inactivated / Q000008:administration & dosage; D017778:Vaccines, Combined / Q000008:administration & dosage
chemical_list: D015721:Diphtheria-Tetanus-Pertussis Vaccine; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines; D018073:Haemophilus Vaccines; D006510:Hepatitis B Antibodies; D017325:Hepatitis B Vaccines; C426944:Hexavac; D011054:Poliovirus Vaccine, Inactivated; D017778:Vaccines, Combined