Effect of Agrimonia procera extract (APE) on TNF α production by porcine PBMC. The TNFα concentration was analyzed in culture supernatant of LPS (1 μg/ml)-stimulated PBMC (2 × 106 per ml RPMI 1640 medium) treated with 0, 0.05, 0.1 or 0.2% APE for 20 h. Non-stimulated cells without APE treatment served as control. PBMC were isolated from 6 healthy piglets. The amount of TNFα was determined using an ELISA. Data represent mean ± SD (n = 6). a,bBars with different superscript letters differ significantly (P < 0.05, Fisher's test).