Using global gene expression patterns to characterize Annexin V positive and negative human monocytes in culture.

To investigate the early apoptosis that may be detected by Annexin V binding to phosphatidylserine and propidium iodide (PI) exclusion in human monocytes. When studying monocytes in culture, less than 40 % of these cells survive after 7 days.,In the first 4 h, 24 % of monocytes in culture develop into Annexin V(+)/PI(-) cells. Human monocytes were investigated at 0 h and sorted into Annexin V(+) and Annexin V(-) by FACS after 4 h. Gene expression was examined by microarray analyses.,At 4 h, Annexin V(+) monocytes versus Annexin V(-) cells showed 1220 differentially expressed genes. Ingenuity Pathway Analysis disclosed 153 genes related to cell death. Among these were caspase activators, caspase 6, Apaf 2 and FAS, as well as the autophagy gene ATG5. In addition, examination of the most up-regulated or down-regulated genes among the 1220 revealed genes involved in other biological processes, as well as genes not yet annotated. These included the non-annotated genes LOC28480 (fold change: 82) and 225767-at (fold change: 68) and the transcription factor SOX 4 (fold change: 24). conclusions: We suggest that apoptosis in cultured monocytes, as evidenced by Annexin V(+), operates through genes well known in apoptosis, but that the process also involves additional genes not commonly associated with apoptosis.