J. Pryjma et al., Alveolar macrophages of children suffering from recurrent infections of respiratory tract are less efficient in eliminating apoptotic neutrophils, PEDIAT PULM, 27(3), 1999, pp. 167-173
During bacterial infections of the respiratory tract, neutrophils (PMN) are
recruited to the lung by various mechanisms, including production of inter
leukin-8 (IL-8) by alveolar macrophages (AM). After fulfilling their defens
e function, PMN become apoptotic and have to be disposed of by AM to preven
t local damage to the lung tissue by oxygen species and proteolytic enzymes
. We measured the levels of IL-8 in the bronchoalveolar lavage (BAL) and th
e ability of AM to engulf senescent PMN in a groups of children with and wi
thout recurrent infections of the respiratory tract. The IL-8 level was mea
sured by enzyme-linked immunosorbent assay (ELISA). The phagocytosis of apo
ptotic neutrophils was evaluated microscopically by the presence of myelope
roxidase positive material in AMI before and after 1 h of incubation with s
enescent PMN.
The data show that children suffering from recurrent infections have increa
sed IL-8 in BAL and that their AM have a lower ability to engulf apoptotic
PMN in vitro. Furthermore, the proportion of annexin V-binding cells was hi
gher in BAL of children with recurrent infections of the respiratory tract
than in normal controls. (C) 1999 Wiley-Liss, Inc.