Henk Parmentier studied Biology (Hydrobiology and Cell biology at Wageningen University, and graduaded for his PhD on intestinal parasite infections in mice at the Veterinary Medicine School (Utrecht University). After a post doc on HIV (UU) he worked on general immunology of farm animals with emphasis on selected chicken lines. The discovery of so-called natural antibodies in chickens about 10 years ago aroused his interest. These antibodies that occur in all the animal species that have been tested to date ancluding pigs and bovine and that until recently were 'dismissed' as background noise appear to play an important role in maintaining the health of an individual. They serve as a first line of defense, but since many of them bind self antigens they keep an individual 'clean' as cleaners of waste products. Many metabolic and behavioural disorders but also sensitivity to infection in man and animals appear to be correlated with or are maybe caused by reduced levels of these antibodies. Interestingly, levels tof natural antibodies turn out to be hereditary, but can still be influenced by ' vaccination' even with 'auto-antigens'. The research now focuses on the factors (genetic, environmental, feed) that influence natural antibody levels and their origin in farm animals.