title: Human colostral phagocytes eliminate enterotoxigenic Escherichia coli opsonized by colostrum supernatant.
abstract: BACKGROUND
  Several elements in colostrum and human milk, including antibodies and nonspecific factors with bactericidal and antiviral activity, may play an important anti-infectious and protective role. In developing countries, enterotoxigenic Escherichia coli (ETEC) is the main etiological agent of diarrhea in low-socioeconomic level children. In the present work, we studied the functional activity of mononuclear (MN) and polymorphonuclear (PMN) phagocytes of human colostrum against ETEC, as well as the interactions between these cells and colostral or serum opsonins.
  
  
  METHODS
  Colostrum samples were collected from 33 clinically healthy women between 48 and 72 hours postpartum. We verified superoxide release in colostral MN and PMN using cytochrome C reduction methods, phagocytosis, and bactericidal activity using acridine orange methods and superoxide dismutase (SOD) in the colostrum supernatants.
  
  
  RESULTS
  Colostral MN and PMN phagocytes exposed to ETEC opsonized with colostrum supernatants caused a significant increase (p<0.05) in superoxide release. Phagocytosis by colostral PMN cells increased significantly (p<0.5) when the phagocytes were incubated with both sources of opsonins (sera and colostrum). Increases in superoxide release in the presence of opsonized bacteria triggered the bactericidal activity of the phagocytes. Phagocyte treatment with SOD decreased their ability to eliminate ETEC. Colostrum supernatant had higher SOD concentrations (p<0.05) compared with normal human sera.
  
  
  CONCLUSIONS
  These results suggest that the ability of phagocytes to eliminate ETEC depends on the activation of cellular oxidative metabolism; moreover, activation of colostral phagocytes is likely an additional breast-feeding protection mechanism against intestinal infections in infants.
authors.affiliation: Institute of Biological Sciences and Health, Federal University of Mato Grosso, Pontal do Araguaia, Mato Grosso, Brazil.
authors.forename: Eduardo Luzía
authors.initials: EL
authors.lastname: França
authors.affiliation: Institute of Health Sciences, University Center of Planalto of Araxá, Araxá, Minas Gerais, Brazil.
authors.forename: Renata Vieira
authors.initials: RV
authors.lastname: Bitencourt
authors.affiliation: Institute of Biological Sciences and Health, Federal University of Mato Grosso, Pontal do Araguaia, Mato Grosso, Brazil.
authors.forename: Mahmi
authors.initials: M
authors.lastname: Fujimori
authors.affiliation: Institute of Biological Sciences and Health, Federal University of Mato Grosso, Pontal do Araguaia, Mato Grosso, Brazil.
authors.forename: Tassiane Cristina
authors.initials: TC
authors.lastname: de Morais
authors.affiliation: Postgraduate Program in Gynecology, Obstetrics and Mastology, Botucatu Medical School, São Paulo State University, São Paulo, Brazil.
authors.forename: Iracema de Mattos Paranhos
authors.initials: Ide M
authors.lastname: Calderon
authors.affiliation: Institute of Biological Sciences and Health, Federal University of Mato Grosso, Pontal do Araguaia, Mato Grosso, Brazil; Postgraduate Program in Gynecology, Obstetrics and Mastology, Botucatu Medical School, São Paulo State University, São Paulo, Brazil.
authors.forename: Adenilda Cristina
authors.initials: AC
authors.lastname: Honorio-França
mesh_terms: D000293:Adolescent; D000328:Adult; D003126:Colostrum / Q000276:immunology*; D054307:Enterotoxigenic Escherichia coli / Q000276:immunology*; D005260:Female; D006801:Humans; D050296:Microbial Viability; D009895:Opsonin Proteins / Q000276:immunology*; D010586:Phagocytes / Q000276:immunology*; D010587:Phagocytosis; D013482:Superoxide Dismutase / Q000032:analysis; D013481:Superoxides / Q000032:analysis; D055815:Young Adult
chemical_list: D009895:Opsonin Proteins; D013481:Superoxides; D013482:Superoxide Dismutase