title: Prospective evaluation of Streptococcus pneumoniae serum antibodies in patients with primary immunodeficiency on regular intravenous immunoglobulin treatment.
abstract: BACKGROUND
  This is a prospective study that assessed pneumococcal antibody levels in PID patients under intravenous immunoglobulin (IVIG) treatment using different brands.
  
  
  METHODS
  Twenty-one patients receiving regular IVIG every 28 days were invited to participate: 12 with common variable immunodeficiency, six with X-linked agammaglobulinaemia and three with hyper-IgM syndrome. One blood sample was collected from each patient just prior to IVIG administration at a three-month time interval during one year. A questionnaire was filled in with patient's demographic data and history of infections during the study period. Streptococcus pneumoniae antibodies against six serotypes (1, 5, 6B, 9V, 14 and 19F) were assessed by ELISA both in patients' serum (trough levels) and in IVIG samples.
  
  
  RESULTS
  Median total IgG trough serum levels were 7.91g/L (range, 4.59-12.20). All patients had antibody levels above 0.35μg/mL to the six serotypes on all four measurements. However, only 28.6% of patients had pneumococcal antibodies for the six analysed serotypes above 1.3μg/mL on all four evaluations during the one-year period. No correlation was found between IgG trough levels and pneumococcal specific antibodies. Eighteen of the 21 patients (85.7%) had infections at some point during the 12-month follow-up, 62/64 (96.9%) clinically classified in respiratory tract infections, four of which were pneumonia.
  
  
  CONCLUSIONS
  Pneumococcal antibodies are present in a high range of concentrations in sera from PID patients and also in IVIG preparations. Even maintaining a recommended IgG trough level, these patients can be susceptible to these bacteria and that may contribute to recurrent respiratory infections.
authors.affiliation: Division of Pediatric Infectious Diseases, Department of Pediatrics, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: R M
authors.initials: RM
authors.lastname: Simão-Gurge
authors.affiliation: Division of Allergy Clinical Immunology and Rheumatology, Department of Pediatrics, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: B T
authors.initials: BT
authors.lastname: Costa-Carvalho
authors.affiliation: Division of Allergy Clinical Immunology and Rheumatology, Department of Pediatrics, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: F A
authors.initials: FA
authors.lastname: Nobre
authors.affiliation: Division of Allergy Clinical Immunology and Rheumatology, Department of Pediatrics, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: I G S
authors.initials: IG
authors.lastname: Gonzalez
authors.affiliation: Division of Pediatric Infectious Diseases, Department of Pediatrics, Universidade Federal de São Paulo, São Paulo, SP, Brazil. Electronic address: m.isabelmp@uol.com.br.
authors.forename: M I
authors.initials: MI
authors.lastname: de Moraes-Pinto
mesh_terms: D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood*; D001938:Brazil; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D016756:Immunoglobulins, Intravenous / Q000627:therapeutic use*; D007153:Immunologic Deficiency Syndromes / Q000276:immunology* / Q000628:therapy; D008297:Male; D011018:Pneumonia, Pneumococcal / Q000276:immunology* / Q000628:therapy; D011446:Prospective Studies; D013296:Streptococcus pneumoniae / Q000276:immunology*; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D016756:Immunoglobulins, Intravenous
keywords: Antibody deficiency; Hypogammaglobinaemia; Intravenous immunoglobulin; Pneumococcal infection; Primary immunodeficiency disease; Streptococcus pneumoniae