Poly(I:C)-induced MPs but not MPs from unstimulated U937 cells increased the production of IL-6 in RASF (mean ± SE: 1873 ± 325 pg/mL, p = 0.002, n = 9 and 476 ± 182 pg/mL, n = 6, respectively) when compared to unstimulated RASF (304 ± 61 pg/mL, n = 9). No changes in proliferation or spontaneous rate of apoptosis were observed in RASF or OASF stimulated with MPs. Treatment of RASF (n = 5) and OASF (n = 5) with FasL or treatment of RASF (n = 7) with TRAIL for 24 h significantly increased apoptosis of SF (p = 0.010; p = 0.036 and p = 0.016, respectively). Poly(I:C)-induced MPs inhibit FasL-induced apoptosis of RASF (% decrease ± SE: 40.2 ± 7.0%; p = 0.001; n = 5) and OASF (41.1 ± 9.5%; p = 0.036, n = 5) and decreased TRAIL-induced apoptosis of RASF (29.9 ± 6.8%, p = 0.093). In contrast, TNFα-induced MPs had no effect on Fas-induced apoptosis in SF (n = 3). MPs from untreated U937 cells did not influence FasL- or TRAIL-induced apoptosis of RASF (n = 5) and OASF (n = 4). Fas was not expressed on the surface of MPs, indicating that Poly(I:C)-induced MP did not act as a decoy to decrease the effective concentration of FasL in cell culture supernatants.