Submitted to: Journal of Reproductive Immunology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/17/1996
Publication Date: N/A
Citation: Interpretive Summary: Breastfeeding is unique in that immune factors are produced in the mother's milk for the protection of the infant. While several studies have focused on the immune factors in mother's milk, few have examined the immune status of the mother herself. In this study the blood B-lymphocytes (white blood cells) were measured at 1-2 weeks, 1, 2, 4 or 8 mo postpartum in 64 breastfeeding, 43 bottle-feeding and 14 control women, who had never been pregnant. Blood B-lymphocytes were depressed immediately after delivery, and increased to control values by 1-4 months. The rise was delayed in breastfeeding women, possibly due to their higher serum prolactin levels. The low percents of B-cells in the early postpartum period suggest that the B-cells might be in mucosal tissues rather than in circulation, or that B- cell production was suppressed in bone marrow. These findings are important for the timing of maternal immunization programs.
Technical Abstract: Lactation is an immunologically unique state when immune factors are produced by the mother for the protection of the infant rather than the mother. While several studies have focused on the immunological composition of human milk, much less information is available on maternal immune status during lactation. Sixty four lactating and 43 bottle-feeding women at 1-2 weeks, 1,2,4 or 8 months postpartum were studied in a cross-sectional design, with 14 nulliparous women as controls. Flow cytometry analysis of peripheral blood lymphocytes showed dynamic, postpartum changes in the B-call subpopulation. Among lactating women, B-cell percents (%CD19+) were significantly lower (p<0.05) than control levels at 1-2 weeks and one month postpartum, but showed a significant, polynomial-linear rise (p<0.05) over time, reaching control values by two to four months postpartum. Bottle- feeding women had an earlier rise in #CD19+ cells, with relative percents always significantly higher than their lactating counterparts. The differing patterns may be due to changes in serum prolactin concentrations because, among the postpartum women, %CD19+ cells were negatively correlated with baseline serum prolactin concentrations. These results have implications for maternal immunization programs designed to enhance maternal and/or infant well-being as well as other maternal health effects related to breastfeeding.