title: Memory B-Cell Pools Predict the Immune Response to Pneumococcal Conjugate Vaccine in Immunocompromised Children.
abstract: BACKGROUND
  The immune responses to pneumococcal conjugate vaccine (PCV) are low in immunocompromised hosts. The effect of memory B cells on the immune response to PCV remains elusive.
  
  
  METHODS
  In this prospective study, 53 children who received 7-valent PCV were enrolled. Antipneumococcal immunoglobulin G (IgG) levels and opsonization index (OI) titers, along with lymphocyte subsets, were investigated in immunocompromised and immunocompetent hosts. Immunocompromised patients comprised 8 hematopoietic stem cell transplant recipients (group A) and 9 immunosuppressive therapy recipients (group B), and controls consisted of 14 children aged >1 year (group C) and 22 infants (group D).
  
  
  RESULTS
  Serotype-specific IgG concentrations and OIs in group A were lower than those in group C. These did not differ among groups B, C, and D. The rates of achieving immunity (defined as an IgG level of 1.0 µg/mL and an OI of 8) in group A were also lower than in group C. Despite the sustained numbers of total T cells and B cells, CD27(+) B-cell and CD4(+) T-cell counts in group A were lower than those in group C. In group B, the immunoglobulin D-expressing CD27(-) B-cell count was only lower than that in group C.
  
  
  CONCLUSIONS
  Circulating numbers of CD27(+) B cells, rather than CD4(+) T cells, may predict the effective PCV responses in immunocompromised children.
authors.affiliation: Department of Pediatrics Department of Pediatrics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hoshina
authors.affiliation: Department of Pediatrics Department of Pediatrics, Yamaguchi University Graduate School of Medicine, Ube.
authors.forename: Shouichi
authors.initials: S
authors.lastname: Ohga
authors.affiliation: Department of Pediatrics.
authors.forename: Junko
authors.initials: J
authors.lastname: Fujiyoshi
authors.affiliation: Department of Pediatrics.
authors.forename: Etsuro
authors.initials: E
authors.lastname: Nanishi
authors.affiliation: Department of Pediatrics.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Takimoto
authors.affiliation: Department of Pediatrics.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Kanno
authors.affiliation: Department of Pediatrics.
authors.forename: Hisanori
authors.initials: H
authors.lastname: Nishio
authors.affiliation: Department of Bacteriology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Saito
authors.affiliation: International Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Akeda
authors.affiliation: International Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University Infectious Disease Surveillance Center, National Institute of Infectious Disease, Tokyo, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Oishi
authors.affiliation: Department of Pediatrics Fukuoka Children's Hospital for Medical Center.
authors.forename: Toshiro
authors.initials: T
authors.lastname: Hara
mesh_terms: D000293:Adolescent; D000907:Antibodies, Bacterial / Q000097:blood; D001402:B-Lymphocytes / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes; D002648:Child; D002675:Child, Preschool; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000276:immunology*; D006801:Humans; D016867:Immunocompromised Host; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D011008:Pneumococcal Infections / Q000517:prevention & control*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000378:metabolism
chemical_list: D000907:Antibodies, Bacterial; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D007074:Immunoglobulin G; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7
keywords: 7-valent pneumococcal conjugate vaccine; after hematopoietic stem cell transplantation; antipneumococcal immunoglobulin G antibody; memory B cell; opsonophagocytic activity