Yolkin promotes differentiation of RAW 264.7 macrophages to the pro-inflammatory phenotype capable of fulfilling efficient phagocytic function

Introduction Yolkin, a protein isolated from hen egg yolk, is postulated to play a key role in embryo development. The aim of this work was to evaluate its differentiating effect on immature RAW 264.7 mouse macrophages by determining their pinocytic and phagocytic capabilities as well as cytokine production. Material and Methods The pinocytosis of neutral red (NR) and phagocytosis of NR-labelled zymosan particles were measured spectrophotometrically, and the production of TNF α, IL-6, and IL-10 in the culture supernatants was evaluated by the immunoenzymatic method. Results Cells of the RAW 264.7 line perform pinocytosis of NR and phagocytosis of NR-zymosan particles more efficiently when incubated with yolkin for 48 h than when in a control culture. Yolkin at a concentration of 10 μg/mL elicited production of TNF-α, IL-6 and IL-10, with a prevalent amount of TNF-α, thus leading to an M1 pro-inflammatory phenotype. Conclusion Following incubation with yolkin, RAW 264.7 macrophages differentiate to an M1 phenotype. The results suggest the possibility of using yolkin as a nutraceutical or functional food ingredient to strengthen defences against infectious agents.