title: Induction of functional secretory IgA responses in breast milk, by pneumococcal capsular polysaccharides.
abstract: Capsule-specific secretory IgA (s-IgA) in breast milk may enhance protection against pneumococcal disease in infants. After immunization of 3 lactating mothers with 23-valent polysaccharide vaccine, specific s-IgA, but not IgG, increased by >2-fold in milk of at least 1 subject for 6 of 7 serotypes. The s-IgA was predominantly IgA1, in secretory form, and highly specific with avidity distinct from serum IgA and IgG. Milk whey from 2 immunized women supported dose- and complement-dependent killing of Streptococcus pneumoniae serotypes 19F and 14 by human neutrophils, as did purified s-IgA to serotype 19F. These data reveal that capsule-specific human s-IgA in breast milk can initiate killing of S. pneumoniae, providing proof of concept that vaccine-induced human mucosal s-IgA can support functional bactericidal activity. Determining the biologic role for s-IgA in killing and inhibiting adherence of S. pneumoniae in vivo will contribute to the development of mucosal vaccines against S. pneumoniae.
authors.affiliation: Institute of Child Health, University of Bristol, Bristol, United Kingdom. Adam.Finn@bristol.ac.uk
authors.forename: Adam
authors.initials: A
authors.lastname: Finn
authors.forename: Qibo
authors.initials: Q
authors.lastname: Zhang
authors.forename: Lynn
authors.initials: L
authors.lastname: Seymour
authors.forename: Claudine
authors.initials: C
authors.lastname: Fasching
authors.forename: Emily
authors.initials: E
authors.lastname: Pettitt
authors.forename: Edward N
authors.initials: EN
authors.lastname: Janoff
mesh_terms: D001422:Bacterial Adhesion / Q000187:drug effects; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000276:immunology* / Q000494:pharmacology; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000517:prevention & control*; D008895:Milk, Human / Q000737:chemistry*; D011008:Pneumococcal Infections / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000276:immunology
chemical_list: D007070:Immunoglobulin A; D022242:Pneumococcal Vaccines; D011135:Polysaccharides, Bacterial