Chitotriosidase activity in human milk from mothers of premature and full-term infants during the first month of lactation.

Objective: The objectives of the present study were to measure the activity of chitotriosidase (ChT) in human milk, to record changes in enzyme activity over time and to determine whether there are differences in activity between the milk of mothers of full-term (FT) and premature (PT) infants.

Patients And Methods: Three samples were collected from each of 28 mothers (26.9+/-4.3 years of age; mean+/-SD) of FT infants (gestational age, 39.1+/-0.9 weeks; birth weight, 3384.8+/-369.8 g.; median, 3485 g) and 28 mothers (26.6+/-3.6 years of age) of healthy PT infants (gestational age, 30.5+/-3.1 weeks; birth weight, 1400+/-492.9 g.; median, 1285 g). Samples were collected at 3, 7 and 28th days after delivery. ChT activity was estimated using the fluorimetric method. ChT activities were calculated and expressed as nanomoles per milliliter per hour.

Results: ChT activity was higher in the PT group than in the FT group at day 3 [170.2 (14.0-294.8) vs. 81.7 (6.9-306.3) nmol/mL/h], day 7 [31.6 (0.0-166.7) vs. 17.2 (0.0-214.1) nmol/mL/h] and day 28 [5.5 (0.0-64.9) vs. 3.4 (0.0-51.6) nmol/mL/h].

Conclusion: The higher ChT activity in milk of mothers of PT infants than those of FT infants suggests the presence of activated macrophages as its main source. ChT is well known to play a role in defense against fungi and have the ability to degrade both colloidal chitin and chitin in the cell wall of Candida albicans. Thus, our findings may indicate that infants have a natural advantage for protection from fungus infections when they are fed by their mothers' milk.