LYSOZYME Lysozyme is present in the lyses mostly gram-positive and few gram-negative bacteria. Contrary to the other protective proteins in human milk(I.e.,IgA and lactoferrin), the concentration of lysozyme decreases during lactation,those of lysozyme increase with prolonged lactation. LYSOZYME Lysozyme is present in the lyses mostly gram-positive and few gram-negative bacteria. Contrary to the other protective proteins in human milk(I.e., IgA and lactoferrin), the concentration of lysozyme decreases during lactation,those of lysozyme increase with prolonged lactation