Fig. 1.

TL1A synergizes with IL-12 and IL-18 to increase IFN-γ production in PBMC and NK cells but does not enhance cytolytic activity of PBMC and NK cells against the NK-sensitive K562 cell line. a PBMC and purified NK cells were cultured with medium (Control) or a maximal concentration of IL-12 and IL-18 without or with TL1A (50 ng/ml), and their cytotoxicity was tested against the NK-sensitive cell line K562 in ⁵¹Cr-release assays and expressed in lytic units (LU₃₀, left panels). Culture supernatants were collected at 72 h and analyzed for IFN-γ content by ELISA (right panels). Results are representative of two experiments with similar results. b PBMC and purified NK cells of the same donor were cultured as in 1A but with a lower IL-12 concentration (40 pg/ml). Results are representative of three experiments for PBMC, two experiments for NK cells. TL1A-treated PBMC produced significantly more IFN-γ (p = 0.05) while no significant difference was seen in cytotoxicity. LU₃₀, the number of effector cells required to lyse 30% of a standard number of target cells, here 10⁴ target cells. Bars SD