Bactericidal activity of human milk leukocytes

Area of Science:

• Immunology
• Lactation Biology
• Infant Health

Background:

• Breast milk is a vital source of nutrition and immunological factors for infants.
• The role of leukocytes in breast milk's protective functions requires further elucidation.

Purpose of the Study:

• To analyze leukocyte concentration and bactericidal activity in breast milk across different lactation stages.
• To investigate the influence of maternal nutritional status on these milk components.

Main Methods:

• Analysis of breast milk samples from 74 women at various lactation stages.
• Quantification of total leukocyte count and differential cell counts (polymorphs, mononuclear leukocytes, lymphocytes).
• Assessment of the bactericidal activity of milk leukocytes.

Main Results:

• Colostrum had a high leukocyte concentration (5,000/mm³), similar to circulation.
• Mature milk showed a reduced concentration (around 2,000/mm³) after 3 months.
• Polymorphs and mononuclear leukocytes comprised 90-95% of milk leukocytes.
• Milk leukocyte bactericidal activity was comparable to circulating leukocytes and unaffected by lactation stage.
• Leukocyte concentration and bactericidal capacity were similar in well-nourished and undernourished women.

Conclusions:

• Breast milk is rich in viable leukocytes with significant bactericidal capabilities.
• These leukocytes likely play a crucial role in protecting infants against infections.
• Maternal nutritional status does not appear to influence the protective factors provided by milk leukocytes.