Yeast culture has anti-inflammatory effects and specifically activates NK cells.

Comparative immunology, microbiology and infectious diseases

PubMedID: 17915321

Jensen GS, Patterson KM, Yoon I. Yeast culture has anti-inflammatory effects and specifically activates NK cells. Comp Immunol Microbiol Infect Dis. 2008;31(6):487-500.
Yeast culture is widely used in animal feed and has been linked to beneficial effects on animal health and production. This study examined the anti-oxidant and immunomodulating effects of a consumable yeast culture, XP, in vitro. An aqueous extract of XP contained anti-oxidants able to enter living cells and quench free radicals. The XP extract induced an increased expression of CD69 and CD25 on NK and NKT cells, and an increased cytotoxic response to K562 tumor cells. The XP extract amplified ProteinA-induced B cell activation in vitro, as measured by induction of the CD86 antigen on B lymphoblasts in 7-day cultures. The data show an anti-inflammatory effect of the XP extract in conjunction with activation of NK cells and B lymphocytes in vitro. Further in vivo studies are needed to examine the impact of XP in animals with bacterial and viral infections, as well as around the time of vaccination.