Amoebicidal activity of milk, apo-lactoferrin, sIgA and lysozyme.
OBJECTIVE
To identify amoebicidal components in human milk and the effect of iron on the amoebicidal activity.


METHODS
Investigation in axenic cultures of Entamoeba histolytica trophozoites.


METHODS
Amoebas were treated with 5%-20% of human, bovine and swine milk, with 10% of human milk fractions (i.e., casein, proteins except casein and fat) or with 1 mg/ml of human milk apo-lactoferrin, human secretory immunoglobulin type A (sIgA) and chicken egg-white lysozyme (i.e., purified proteins). Milk proteins were detected using immunoblot. Confocal microscopy was used to define the interaction of milk proteins (100 microM each) and amoebas. Experiments were done at least three times in triplicate, and mean and standard deviations were calculated.


RESULTS
Human and bovine milk were amoebicidal showing a concentration-dependent effect. The amoebicidal effect was increased in the absence of iron. Milk protein fractions, with the exception of casein, were the components responsible for the amoebicidal activity found. Apo-lactoferrin, sIgA and lysozyme were identified in the amoebicidal milk protein fraction. Apo-lactoferrin showed the major amoebicidal effect. These proteins, either alone or in combination, showed a killing effect on the trophozoites. They bound to the amoebic membrane causing cell rounding, lipid disruption and damage.


CONCLUSIONS
Milk proteins such as apo-lactoferrin, sIgA and lysozyme are able to kill Entamoeba histolytica trophozoites. This study confirms the importance of feeding breast milk to newborns.
León-Sicairos
Nidia
N
Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del I.P.N., Apdo. 14-740, México, D.F. 07000, México.
López-Soto
Fernando
F
Reyes-López
Magda
M
Godínez-Vargas
Delfino
D
Ordaz-Pichardo
Cynthia
C
de la Garza
Mireya
M
D000563:Amebicides / Q000494:pharmacology*; D000818:Animals; D001059:Apoproteins / Q000032:analysis / Q000494:pharmacology*; D001942:Breast Feeding; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004748:Entamoeba histolytica / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000032:analysis / Q000494:pharmacology*; D007781:Lactoferrin / Q000032:analysis / Q000494:pharmacology*; D018613:Microscopy, Confocal; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis / Q000494:pharmacology; D008895:Milk, Human / Q000737:chemistry*; D009113:Muramidase / Q000032:analysis / Q000494:pharmacology*; D013552:Swine
D000563:Amebicides; D001059:Apoproteins; D007071:Immunoglobulin A, Secretory; D008894:Milk Proteins; C039223:apolactoferrin; D009113:Muramidase; D007781:Lactoferrin