(P10-016-24) Associations Between Clinical and Subclinical Mastitis on Human Milk Immunological Profiles

Objectives: Mastitis is an inflammatory condition that is a primary cause of early breastfeeding cessation. However, changes in milk composition prior to and during mastitis are not entirely described. To fill this research gap, we tested the hypothesis that the immune profiles of milk produced by healthy women and those experiencing subclinical (SCM) or clinical (CM) mastitis differ, and that the concentrations of some immune factors shift before onset of mastitis.

Methods: Milk samples (n = 61) were collected from 14 healthy (H, control) women, 10 women who developed CM (cases), and 8 women who developed SCM (cases, defined by somatic cell count) the week before and the week of mastitis development. Cases and controls were matched based on time postpartum. Concentrations of 36 immune factors (immunoglobulins, cytokines, chemokines, and growth factors) were quantified via enzyme-linked immunosorbent immunoassays. Differences in individual immune factors and immunological profiles among health-status groups were evaluated, and significance was declared at p< 0.05.

Results: Immune profiles in milk produced by women experiencing CM vs. SCM were different from each other, and from milk produced by H women. Although there were no differences in immune profiles between women with SCM vs. CM the week prior to symptoms, both groups differed from H women. Concentrations of 26 compounds were higher in milk produced by CM women compared to H, and concentrations of 6 of these [including interleukin (IL) 2, IL4, and basic fibroblast growth factor (FGFb)], were already higher the week prior to symptoms. In general, concentrations of immune compounds in milk produced by SCM women were intermediate between those of milk produced by CM and H women.

Conclusions: Immune profiles of milk produced by women experiencing CM are different from those of H before and during symptoms, whereas immune profiles of milk produced by women experiencing SCM are intermediate between H and CM. Further research is needed to establish if differences observed in individual compounds can be used to improve mastitis risk prediction prior to onset of symptoms.

Funding Sources: National Institutes of Health NICHD R01HD092297 and US Department of Agriculture National Institute of Food and Agriculture, Hatch project IDA01643. Milk collection kits provided by Medela Inc.