ARACHIDONIC-ACID INDUCES DNA-FRAGMENTATION IN HUMAN POLYMORPHONUCLEARNEUTROPHIL GRANULOCYTES

We analyzed DNA-fragmentation in human polymorphonuclear neutrophil gr anulocytes (PMNs) from healthy donors after addition of exogenous arac hidonic acid (AA) and eicosapentaenoic acid (EPA) by flow cytometry (p ropidium iodide staining of DNA and DNA strand break detection). The P MNs were incubated from 30 min up to 48 hours in RPMI 1640 which was s upplemented with different concentrations of AA or EPA (5-40 mu M). In contrast to EPA the addition of AA led to a significant increase in a poptosis up to 67.8% compared to the RPMI-control whereas the addition of EPA led to an inhibition of DNA-fragmentation. When the cells were incubated with MK 886 (1 mu M, inhibitor of leukotriene biosynthesis) an increase in DNA-fragmentation (up to 63.3%) was observed. Converse ly, in the presence of indomethacin (1 mu M, inhibitor of prostanoid s ynthesis) an inhibition in DNA-fragmentation (up to 60.9%) occurred. F urthermore, preincubation of PMNs with pentoxifylline (1 mM, phosphodi esterase inhibitor) reduced AA-stimulated DNA-fragmentation up to 43.4 %. These data provide evidence for the involvement of AA and distinct AA metabolites in the regulation of apoptosis in human PMNs.