Human colostral and breast milk cells. A light and electron microscopic study

Area of Science:

• Immunology
• Human Lactation Biology

Background:

• Colostrum and breast milk are crucial for neonatal immunity and nutrition.
• Leukocyte populations within human milk play a significant role in infant development.

Purpose of the Study:

• To analyze the cellular composition of human colostrum and breast milk.
• To track changes in leukocyte counts and types during the initial weeks of lactation.
• To characterize the functional and ultrastructural properties of milk macrophages.

Main Methods:

• Collection of colostrum and breast milk samples from 74 lactating women.
• Sequential sampling from 18 women to observe temporal changes.
• Cell counting, differential analysis, and ultrastructural examination of leukocytes.

Main Results:

• Mean leukocyte count in colostrum was 3190 cells/mm3, with macrophages predominating.
• Leukocyte counts decreased around delivery and at lactation onset, with a shift in cell types.
• Epithelial cells and cytoplasmic fragments became prominent after 1-2 weeks.
• Milk macrophages exhibited characteristics similar to those found elsewhere in the body.

Conclusions:

• Leukocyte numbers remain relatively stable for the first two weeks of lactation, then decline.
• The changing cellular composition of breast milk may influence neonatal immune responses.
• Milk macrophages are functionally and morphologically equipped for immune surveillance and nutrient processing.