Volume 1 • Issue 1 • 1000104 J Medical Microbiol Diagnosis ISSN: 2161-0703 JMMD, an open access journal Research Article Open Access França et al., J Medical Microbiol Diagnosis 2012, 1:1 http://dx.doi.org/10.4172/2161-0703.1000104 Research Article Open Access Medical Microbiology & Diagnosis Fluctuation in the Functional Activity of Human Colostrum Phagocytes to Streptococcus pneumoniae and Enteropathogenic Escherichia coli Eduardo Luzía França 1,2 , Cristiane Castro Pernet Hara 2 , Danny Laura Gomes Fagundes 2 , Nayara Aires Peixoto Lima 3 , Silvia Hanna Bilotti Ratto 3 , Adenilda Cristina Honorio-Franca 1,2 * 1 PostGraduate Program in Immunology and Parasitology, Institute of Biological and Health Sciences, Federal University of Mato Grosso, Barra do Garça, MT 2 PostGraduate Program in Material Science, Institute of Biological and Health Sciences, Federal University of Mato Grosso, Barra do Garças, MT 3 Institute of Biological and Health Science, Federal University of Mato Grosso, Pontal do Araguaia, MT, Brazil *Corresponding author: AC Honorio-França, Instituto de Ciências Biológicas e da Saúde, UFMT, Pontal do Araguaia, MT, Rodovia BR070, Km 5 s/no, Barra do Garças, MT, Brazil, Tel: 55-6634021121; Fax: 55-6634021117 CEP: 78698-000; E-mail: denifran@terra.com.br Received November 22, 2011; Accepted December 26, 2011; Published January 02, 2012 Citation: França EL, Pernet Hara CC, Gomes Fagundes DL, Peixoto Lima NA, Bilotti Ratto SH, et al. (2012) Fluctuation in the Functional Activity of Human Colostrum Phagocytes to Streptococcus pneumoniae and Enteropathogenic Escherichia coli. J Medical Microbiol Diagnosis 1:104. doi:10.4172/2161-0703.1000104 Copyright: © 2012 França EL, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Colostrum was shown to protect children against gastrointestinal and respiratory infections and to exhibit chronobiological variations in cellular and soluble components. However, circadian variations in the activity of these colostral elements are only partially understood. This study compared colostrum samples collected in the diurnal and nocturnal periods by assessing phagocytic activity against enteropathogenic Escherichia coli (EPEC) and Streptococcus pneumoniae (S. pneumoniae) as well as the role of colostral cells and soluble elements. Colostrum samples were collected from 30 mothers during both day and night. Superoxide anion release, phagocytosis and bactericidal activity by colostral mononuclear (MN) and polymorphonuclear (PMN) phagocytes in the presence of EPEC or S. pneumoniae were determined. Colostrum samples collected in the diurnal period had higher superoxide release in opsonized than in non-opsonized EPEC and S. pneumoniae, whereas in nocturnal samples it was increased in PMN phagocytes incubated with serum-opsonized S. pneumoniae. MN and PMN phagocytes in colostrum collected in both periods exhibited phagocytic activity for the bacteria tested. The highest EPEC killing by MN phagocytes was observed in samples collected in the diurnal period. The bactericidal activity of PMN phagocytes against EPEC was higher when bacteria were opsonized and in samples collected in the diurnal period. For opsonized S. pneumoniae, phagocytes had similar bactericidal activity, irrespective of colostrum collection period. These data support the hypothesis that there is a fluctuation in the functional activity of colostral phagocytes, which is dependent on synchronization among feeding time, pathogen features and infection area. Keywords: Bacteria, Colostrum, Infections, Phagocytes, Opsonin Introduction Protective factors in colostrum and breast milk combat pathogens in children [1-5]. Colostrum in particular is a rich source of nutrients and the host of immunological components that play an important role in infant protection against gastrointestinal and respiratory infections [3] commonly associated to specific pathogens. is is true for acute diarrhea, the second main cause of death in infants of low socioeconomic status in developing countries [6]. During their first year of life, the main etiological agent of diarrhea in infants is enteropathogenic Escherichia coli (EPEC) [7,8]. EPEC is also a major causative agent of death from diarrhea in children under five years of age [9]. Another important pathogen that attacks infants is the bacterium Streptococcus pneumoniae. Mostly associated with acute otitis media and S. pneumoniae is the second most common cause of meningitis in children under 2 years of age [10]. Colostrum and breast milk, which are known to play an anti- infection, protective role against pathogens [1,3,11], are particularly rich in secretory IgA (SIgA), which blocks bacterial adherence to human epithelial cells, neutralizes toxins and prevents viral infections [3]. IgA acts as an opsonin, thereby increasing free radical production, phagocytosis and microbicidal activity of colostral cells [8,15,13] through interactions with the Fcα receptor [1,11,12]. Colostrum contains antibodies that combat a variety of bacteria and has the capacity to inhibit the adhesion of different EPEC serotypes [7]. IgA contained in colostrum and breast milk has proven to be effective against a number of microorganisms [12]. In addition to antibodies, soluble bioactive components and anti- infectious factors, human colostrum contains large amounts of viable leukocytes (1x10 9 cells/mL in the first days of lactation), especially macrophages and neutrophils [13]. ese cells produce free radicals and have phagocytic and bactericidal activity [14,15]. In bacterial infections, phagocytes are known to be the main cell lineage in host defense [15]. Stimulatory signals released during SIgA interaction with its Fc receptor activates human colostral phagocytes [12,16,17], which exhibit phagocytic activity and produce oxygen-free radicals. e bactericidal activity of colostral mononuclear phagocytes aſter opsonization with SIgA is equivalent to that of mononuclear and polymorphonuclear phagocytes from peripheral blood [1,11]. Colostrum may represent a complete micro-environment, in which both soluble and cellular components act together [1,3]. Given that colostrum is the secretion with the highest amount of SIgA, the biological activity and interactions of this antibody are of