Abstract
The influence of lysozyme feeding on the production of serum immunoglobulins [Ig] and intestinal secretory IgA was studied in full-term and premature infants, from birth up to the age 6 mo. Serum Ig were not influenced by lysozyme administration. An increase in secretory IgA was found in stool filtrates of full-term lysozyme-fed infants; no secretory IgA was detected in controls. In this way lysozyme feeding partly substituted for passive transfer of secretory IgA from maternal milk.