L. reuteri strains proficient in biofilm formation suppress TNF production. Cell-free supernatants from L. reuteri biofilms cultured in 24-well plates (A) or flow cells (B) were added to human monocytoid cells in the presence of E. coli-derived LPS. Quantitative ELISAs measured the amounts of human TNF produced by THP-1 cells. As biofilms, TNF inhibitory strains (ATCC PTA 6475 and ATCC PTA 5289) retained their ability to suppress TNF produced by LPS-activated human monocytoid cells. L. reuteri ATCC PTA 6475 and ATCC PTA 5289 biofilms cultured in 24-well plates (A) inhibited TNF by 60% and 50% respectively, (ANOVA, p < 0.02). Supernatants of L. reuteri ATCC PTA 5289 cultured in a flow cell (B) inhibited TNF by 73% when compared to the media control (ANOVA, p < 0.0001).