Increased production of IFN-γ by natural killer cells triggered with bone marrow-derived dendritic cells cultured in the presence of retinoic acid.

All-trans-retinoic acid (RA), a vitamin A metabolite, is beginning to be explored as an immunopharmacologic agent. While its effects on dendritic cells and the induction of regulatory T cells have been recognized, little is known about the effect of RA on dendritic cell-natural killer cell (DC-NK) crosstalk. DC-NK crosstalk is important in directing the innate immune response, as well as subsequent adaptive immune response during viral infection, cancer, pregnancy, as well as organ transplantation.

A Lactobacillus rhamnosus strain induces a heme oxygenase dependent increase in Foxp3+ regulatory T cells.

We investigated the consequences of feeding with a Lactobacillus species on the immune environment in GALT, and the role of dendritic cells and heme oxygenase-1 in mediating these responses. Feeding with a specific strain of Lactobacillus rhamnosus induced a significant increase in CD4+CD25+Foxp3+ functional regulatory T cells in GALT. This increase was greatest in the mesenteric lymph nodes and associated with a marked decrease in TNF and IFNγ production.