[Serum siderophilin (transferrin) and ekkrinosiderophilin (lactoferrin) as non-specific microbiostatic agents in human health and disease: clinical implications (author's transl)].

A short historical review of the antimicrobial effects of siderophilin, the iron chelator in human plasma and serum, is followed by a presentation of the rational basis for assigning it a role in the overall defence mechanisms of the host against infectious disease. Details are given of the qualitative and quantitative activities of normal and pathological sera on the growth and nutrition of several pathogenic bacteria and the fungus Candida albicans as governed by the percentage iron saturation of their contained siderophilin. Staphylococcus aureus is differentiated from Staphylococcus albus by its ability to grow in normal serum whose percentage iron saturation affects not only the metabolism of Staphylococcus aureus but also its production of diffusible factors and sensitivity to antibiotics. The protein iron chelator of bodily secretions, ekkrinosiderophilin, found in relatively high concentrations in human milk is likewise evaluated for its antimicrobial properties and their relevance to the health of the newborn.