Figure 1.

Activation of human monocytes leads to selective resistance to apoptosis. Elutriated monocytes were cultured in RPMI medium 1640 supplemented with 20% pooled human serum and activated with E. coli LPS (25 ng/ml) for 6 hr before the introduction of indicated apoptotic agents. Staurosporine, C2-ceramide, and etoposide were added at 1.1 μM, 50 μM, and 10.5 μM, respectively. Anti-Fas antibody was used at a concentration of 500 ng/ml. A dose of 15 J/m² was used in UV irradiation experiments. The cells were then cultured for an additional 12 hr before harvesting to assess the extent of oligonucleosomal DNA fragmentation as described in Materials and Methods. Similar results were obtained from monocytes derived from three other donors.