Modulation of TNF production by L. reuteri is strain-dependent. Cell-free supernatants from stationary phase L. reuteri cultures (planktonic cells) were added to human monocytoid cells in the presence or absence of E. coli-derived LPS (no LPS-black bars, LPS-gray bars). Quantitative ELISAs measured the amounts of human TNF produced by THP-1 cells. In the absence of LPS, supernatants from L. reuteri CF48-3A and ATCC 55730 stimulated TNF by human THP-1 cells, while supernatants from ATCC PTA 6475 and ATCC PTA 5289 did not induce TNF production. However, L. reuteri CF48-3A and ATCC 55730 did not suppress TNF production by LPS-activated cells, while PTA 6475 and ATCC PTA 5289 inhibited production of TNF by 76% and 77% respectively, when compared to the media control (ANOVA, p < 0.001).