The antibacterial activity of lactoferrin and neonatal E. coli infections. A selective and critical review.

Abstract

In 1960, Montreuil et al.1 among others described a method for isolating and purifying an iron-chelating protein from human milk now known as lactoferrin (Lf). In their discussion they made a suggestion which we are still trying to substantiate: “une activite antibiotique vis-a-vis de certains germes pathogenes pour le Nourrisson”. The suggestion that lactoferrin is antibacterial was based on the seminal paper by Schade & Caroline in 19442. They used raw hen egg white to stabilize a bacteriophage during lyophilization and observed that its host, Salmonella dysenteriae, was inhibited by the egg white; this inhibition could be reversed by the addition of iron. After a suitable ‘incubation time’ of about 20 years, this discovery, by serendipity, became the beginning for all aspects of iron and bacterial infection and immunity, as we now know. In 1961, Hanson3 discovered secretory immunoglobulin A (sIgA) which eventually led to the concept of Mucosal Associated Lymphoid Tissue (MALT)—the gut and lung, mammary, salivary and lacrymal glands, and the genital tract. In addition to sIgA, secretions can also contain other non-antibody protective proteins such as lactoferrin (Lf), lysozyme (LZ), lactoperoxidase (LP) and xanthine oxidase (XO). LP is the enzyme which catalyses the bacterial activity of the lactoperoxidase-thiocyanate-hydrogen peroxide system (LP-system)4.