Pretreatment with orange oil preparation attenuates LPS-induced expression of TNFα. Cells pretreated with HBSS or the orange oil in soy were challenged 12 hr later with LPS (3 ug/ml medium) or were left unchallenged. At 4 hr after LPS challenge, TNFα transcript levels were measured using real time RT-PCR. Data are presented as fold change from time-matched HBSS-treated controls after normalization to expression of actin. * indicates significantly different from cells HBSS pretreated and LPS challenged (P < 0.004) by Student's t test.