269 Animal Science Papers and Reports vol. 29 (2011) no. 4, 269-280 Institute of Genetics and Animal Breeding, Jastrzębiec, Poland Bovine milk proteins as the source of bioactive peptides influencing the consumers’ immune system – a review Magdalena Szwajkowska 1, *, Anna Wolanciuk 1 , Joanna Barłowska 1 , Jolanta Król 1 , Zygmunt Litwińczuk 2 1 Department of Commodity Science and Processing of Raw Animal Materials, University of Life Sciences in Lublin, Akademicka 13, 20-950, Lublin, Poland 2 Department of Breeding and Protection of Genetic Resources of Cattle, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland (Received January 21, 2011; accepted September1, 2011 ) The present review describes selected peptides derived from bovine milk proteins and demonstrates their effect on the human immune system. Apart from their obvious nutritive value milk proteins and products of their degradation (peptides) have multiple biological functions. Bovine milk, fermented milk drinks and cheeses are the most abundant sources of biologically active peptides. One of the primary functions of milk is to protect the health of a newborn organism by the virtue of the fact that milk contains many proteins, which exhibit bacteriostatic and bactericidal properties in their intact form. Ingestion of bovine milk by humans causes that bioactive peptides are evoked from delivered proteins during the course of digestion. They possess not only immunomodulatory, but also antibacterial, antiviral and antifungal properties. KEY WORDS: antimicrobial activity / cattle / immunomodulation / milk / peptides / protein Proteins are essential and integral components of food as a source of energy and exogenous amino acids necessary for growth of a living organism. Bovine milk is an excellent source of proteins of high biological value. It is characterized by well- balanced amino acid profile and exceptionally high digestibility. Apart from their obvious nutritive value, milk proteins and products of their degradation (peptides) **Corresponding author: magda.szwajkowska@gmail.com