OBJECTIVETo investigate the effect of necrotic cells on the secretion of inflammatory cytokines.

METHODSRAW264.7 macrophages and necrotic mouse thymocytes induced by heating were incubated for 18 h at a ratio of 5:1 in the absence or presence of lipopolysaccharide (LPS, 100 ng/ml). The supernatant of the cell culture was collected and the expression and secretion of the pro-inflammatory cytokines were measured using Bio-Plex suspension system.

RESULTSThe secretions of tumor necrosis factor-alpha (TNF-alpha) and interlukine-6 (IL-6) by macrophages co-cultured with the necrotic cells were significantly enhanced as compared with the control cells. The necrotic cells also significantly augmented the secretion of the pro-inflammatory cytokines induced by LPS.

CONCLUSIONNecrotic cells not only induces pro-inflammatory cytokine expression by themselves but also work synergistically with LPS to enhance the cytokine production, suggesting the important roles of necrotic cells to initiate and maintain the inflammatory responses.