title: Recurrent respiratory infections, specific antibody deficiencies, and memory B cells.
abstract: OBJECTIVE
  To investigate the immunological phenotypes detected in children with recurrent upper and lower respiratory infections that have normal total immunoglobulin concentrations.
  
  
  METHODS
  A cohort of over 60 children with recurrent respiration infections was evaluated for specific antibody deficiencies (SAD) and for memory B-cell abnormalities. A control group of children without recurrent infections was also evaluated. Evaluation included a detailed history of immunizations with pneumococcal vaccines; determination of IgM, IgG, IgA, and IgE concentrations; measurement of anti-pneumococcal polysaccharide antibody levels by ELISA and expression of CD27, IgD, and IgM on peripheral CD19(+)B cells by flow cytometry to determine the proportions of naive, IgM-memory B cells, and class-switched memory B cells.
  
  
  RESULTS
  Patients were classified as having a SAD to either pure polysaccharides (PPV-SAD) or to conjugate polysaccharides (PCV-SAD) based on the number of polysaccharides to which they developed an adequate antibody response. A normal response to only 2 or fewer of 7 PCV or PPV serotypes was considered as evidence of SAD. Forty-one patients without SAD and 26 with SAD were identified. IgM-memory B cells were low in 3 of 41 patients without SAD; in 3 of 5 PPV-SAD patients; and in 10 of 21 PCV-SAD patients. Class-switched memory B cells were low in 19 of 41 patients without SAD; in all 5 patients with PPV-SAD; and in 11 of 21PCV-SAD patients.
  
  
  CONCLUSIONS
  Patients with recurrent infection with or without SAD may have low IgM- and/or class-switched memory B cells. Ongoing research aims to determine the prognostic implications of these differences in patients with SAD.
authors.affiliation: Department of Pediatrics, Allergy/Immunology Division, Louisiana State University Health Sciences Center, Jeffrey Modell Diagnostic Center for Primary Immunodeficiencies and Children's Hospital, 200 Henry Clay Avenue, New Orleans, LA 70118, USA. lleiva@lsuhsc.edu
authors.forename: Lily E
authors.initials: LE
authors.lastname: Leiva
authors.forename: Hanh
authors.initials: H
authors.lastname: Monjure
authors.forename: Ricardo U
authors.initials: RU
authors.lastname: Sorensen
mesh_terms: D000293:Adolescent; D016175:B-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004406:Dysgammaglobulinemia / Q000276:immunology*; D006801:Humans; D017578:Immunoglobulin Class Switching; D007074:Immunoglobulin G / Q000276:immunology; D007156:Immunologic Memory; D011018:Pneumonia, Pneumococcal / Q000276:immunology; D012141:Respiratory Tract Infections / Q000276:immunology*; D055815:Young Adult
chemical_list: D007074:Immunoglobulin G