Lysozyme in human body fluids

The activity of lysozyme was studied in the following body fluids using the diffusion method on agarose gel: blood serum of adults and children, umbilical cord blood serum, cerebrospinal fluid, amniotic fluid, urine, saliva, gastric juice, bile, tears, mothers' milk, sperm of a healthy subject, and exudates. From the results obtained it was found that lysozyme is present in almost all body fluids, though in different amounts. In serum its activity is normally from 7 to 13 mg/l. The highest content was found in tears, about 120 times higher than in serum. A considerable amount of lysozyme was found in gastric juice, about 8 times more than in normal serum. Lysozyme activity is lowest in or absent from urine, bile and cerebrospinal fluid. In other body fluids the activity of lysozyme was found to be the same as in serum.