Cranberry bioactives promote activation and proliferation of innate immune cells

Abstract

A previous human intervention study showed that consumption of a cranberry beverage enhanced proliferation of γδ‐T cells and NK cells when they were stimulated ex vivo. To explore potential mechanisms, we asked if we could replicate this observation using in vitro PBMC cultures. Buffy coats were obtained (LifeSouth, Gainesville, Fl) and incubated with several concentrations of cranberry fraction E or F. Cell counts, proliferation and activation of γδ‐T cells, NK cells and NK‐T cells were determined before culture, at 24h and 10d by flow cytometry. In general, all three cell types required more than 24 hours for proliferation to occur. There was a dose response to both cranberry fractions. Cell activation was demonstrated by an increased expression of CD69, an early activation marker on γδ‐T cells and CD314 (NKG2D) on the NK and NK‐T cells. Activation was evident within 24h and was apparent but much lower after 10d. In vivo, only gut immune cells would come into contact with these cranberry polyphenols, however, as one of our first lines of defense; this is an important population to maintain. Supported by Ocean Spray Cranberries, Inc. and AES, UF