PROGRAMMED CELL-DEATH (APOPTOSIS) IN HUMAN MONOCYTES INFECTED BY INFLUENZA-A VIRUS

Although infection of monocytes by influenza A virus primes for a high cytokine release, it also leads to cell death within 20-30 hours. In this brief report, we demonstrate that influenza A virus-induced monoc yte killing was due to programmed cell death (apoptosis) and not to ne crosis. Morphologically, chromatin condensation and margination occurr ed and biochemically, an apoptosis-specific internucleosomal DNA fragm entation into multimers of 180 bp (<<DNA ladder>>) was found. Inductio n of apoptosis and not necrosis in influenza A virus-infected monocyte s may serve three purposes: 1. Virus replication is limited, 2. a prim ing for a high cytokine response is initiated and 3. damaging and infl ammation-inducing lysosomal enzymes are held back from monocytes under going controlled cell death.