Changes in immunomodulatory constituents of human milk in response to active infection in the nursing infant

INTRODUCTION: To investigate whether immunologic factors in breast milk change in response to nursing infants' infection. RESULTS: Total CD45 leukocyte count dropped from 5,655 (median and interquartile range: 1,911; 16,871) in the acute phase to 2,122 (672; 6,819) cells/ml milk after recovery with macrophage count decreasing from 1,220 (236; 3,973) to 300 (122; 945) cells/ml. Tumor necrosis factor-alpha (TNF alpha) levels decreased from 3.66 +/- 1.68 to 2.91 +/- 1.51 pg/ml. The decrease in lactoferrin levels was of borderline statistical significance. Such differences were not recorded in samples of the controls. Interleukin-10 levels decreased in the sick infants' breast milk after recovery, but also in the healthy controls, requiring further investigation. Secretory immunoglobulin A levels did not change significantly in the study or control group. DISCUSSION: During active infection in nursing infants, the total number of white blood cells, specifically the number of macrophages, and TNFa levels increase in their mothers' breast milk. These results may support the dynamic nature of the immune defense provided by breastfeeding sick infants. METHODS: Breast milk from mothers of 31 infants, up to 3 months of age, who were hospitalized with fever, was sampled during active illness and recovery. Milk from mothers of 20 healthy infants served as controls.