Temporal fluctuations of cytokine concentrations in human milk

Abstract

Circadian rhythms affect the circulating levels of proteins that can modulate immune responses. Cytokines represent a group of proteins present in breast milk that modulate the immune system, but the effects of fluctuations of these proteins have not yet been elucidated. In this work, the cytokines present in human milk were quantified, taking into account the phases of the day and the maturation stages of human milk. Samples were collected at different stages of milk maturation and in two phases, day and night. The levels of cytokines IL-2, IL-4, IL-6, IL-10, TNF-α, INF-γ and IL-17 were evaluated by flow cytometry. All quantified cytokines showed chronobiological variations with regard to the phase of day and/or stage of breast milk maturation. These data indicate that cytokines are subjected to fluctuations, and this knowledge is important for the use of human breast milk as an intervention strategy.