TSN caused transient activation and subsequent deactivation of monocytes. (A) Monocytes were cultured with the indicated TSN for 0 to 72 hours, after which the cytokine concentrations were determined by enzyme-linked immunosorbent assay (left panels). For the TSN pretreatment (right panels), the cells were incubated with TSN for the indicated time periods, washed, and re-incubated with the same TSN for 18 hours. TSN from CNE1 and THP1 cells did not induce the transient activation of monocytes. (B) Monocytes were pretreated with TSN from U251 (shaded bars), THP1 (solid bars), or medium (open bars) or cells for 10 hours. Thereafter, the cells were washed twice and recultured in medium alone or with the indicated TSN for 18 hours. Values given represent the mean (± SE) of 4 separate experiments; *P < .05 and **P < .01, compared with untreated monocytes.