title: Salivary antibody response to streptococci in preterm and fullterm children: a prospective study.
abstract: OBJECTIVE
  Secretory immunoglobulins present in mucosa surfaces represent the first line of defense of the adaptive immune system against infectious challenges. Preterm (PT) neonates' humoral immunity is diminished compared to full-term (FT) newborns. The identification of important antigens (Ags) of virulence of oral species may help in the investigation of the mechanisms of antigenic stimulation and the development of the mucosal immune response. In the present study, we measured saliva levels of immunoglobulins A (IgA) and M (IgM) and characterized the specificity of IgA against Ags of several streptococcal species found early in life.
  
  
  METHODS
  This was a prospective observational study. Salivary IgA (sIgA) antibody responses to bacterial species that are prototypes of pioneer (Streptococcus mitis, S. sanguinis, S. gordonii) and pathogenic (Streptococcus mutans) microorganisms of the oral cavity were studied in FT and PT children in two visits: at birth (T0) and at 3 months of age (T3). Salivas from 123 infants (72 FT and 51 PT) were collected during the first 10h after birth (T0) and again at 3 months of age (T3). Salivary levels of IgA and IgM antibodies were analysed by enzyme-linked immunosorbent assay (ELISA). A subgroup of 26 FT and 24 PT children were compared with respect to patterns of antibody specificities against different streptococci Ags using Western blot assays.
  
  
  RESULTS
  No significant differences (P>0.05) in salivary levels of IgA and IgM between FT and PT babies were found at birth. At T3, mean sIgA values were similar between groups and sIgM levels were significantly higher in PT than FT (P<0.05). Western blot assays identified positive IgA response to streptococci in the majority of children, especially in the FT group. There were some differences between groups in relation to the frequency of children with positive response to Ags and intensity of IgA response. In general, oral streptococci Ags were more frequently detected and bands were more intense in FT than in PT, especially in T3. Prospective analysis of patterns of sIgA against Ags of different streptococcal species revealed an increase in complexity of the sIgA antibody response from the first day of birth (T0) to T3 in PT and FT.
  
  
  CONCLUSIONS
  The patterns of sIgA response to streptococci Ags appear to be influenced by the gestational age, which might reflect the level of immunological maturity of the mucosal immune system.
authors.affiliation: Department of Pediatrics, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Mariana Castro Loureiro
authors.initials: MC
authors.lastname: Borges
authors.affiliation: Department of Pediatrics, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Maria Lucia Talarico
authors.initials: ML
authors.lastname: Sesso
authors.affiliation: Department of Pediatrics, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Luciana Rodrigues
authors.initials: LR
authors.lastname: Roberti
authors.affiliation: University of Uberaba, Minas Gerais, Brazil.
authors.forename: Maria Angélica Hueb
authors.initials: MA
authors.lastname: de Menezes Oliveira
authors.affiliation: Department of Pediatrics, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; University of Uberaba, Minas Gerais, Brazil. Electronic address: ruchele_nogueira@yahoo.com.br.
authors.forename: Ruchele Dias
authors.initials: RD
authors.lastname: Nogueira
authors.affiliation: University of Uberaba, Minas Gerais, Brazil.
authors.forename: Vinicius Rangel
authors.initials: VR
authors.lastname: Geraldo-Martins
authors.affiliation: Department of Pediatrics, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Virginia Paes Leme
authors.initials: VP
authors.lastname: Ferriani
mesh_terms: D000917:Antibody Formation / Q000276:immunology*; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000276:immunology; D008297:Male; D011446:Prospective Studies; D011506:Proteins / Q000276:immunology; D012463:Saliva / Q000737:chemistry / Q000276:immunology* / Q000382:microbiology; D013291:Streptococcus / Q000276:immunology*
chemical_list: D007071:Immunoglobulin A, Secretory; D007075:Immunoglobulin M; D011506:Proteins
keywords: IgA; Prematurity; Saliva; Streptococcus mitis; Streptococcus mutans