Evidence is presented that interleukin (IL)-2 maintains viability of h
uman polymorphonuclear cells (PMN) in culture by preventing these cell
s from undergoing programmed cell death (PCD) and induces the synthesi
s of new RNA and protein. Our laboratory has recently discovered that
human PMN constitutively express IL-2 beta receptor and more important
ly, PMN are able to respond functionally to IL-2 by enhanced growth in
hibitory activity against an opportunistic fungal pathogen, Candida al
bicans. We now report that IL-2 was able to interfere with the PCD pro
cess and reduce the number of apoptotic PMN IN to < 40% in 72-h cultur
e. Freshly isolated PMN usually underwent a time-dependent aging proce
ss and > 80% of PMN cultured in medium alone for 72 h showed morpholog
ic features of PCD as depicted by hematoxylin and eosin staining as we
ll as by electron microscopy. During the PCD process, untreated PMN no
t only exhibited condensed nuclear structure and decrease in cell size
, but also displayed DNA fragmentation. DNA fragmentation in PMN was p
revented by IL-2. Prevention of PCD by IL-2 was associated with an inc
rease in new RNA and protein synthesis in PMN, which map reflect cytok
ine induction: such as tumor necrosis factor, as we have recently show
n. Thus, our data expands our current understanding of PMN in that the
y may be an active component of the immune system, with a longer life-
span when activated than expected.