Infection and Immunity, December 1998, p. 5999-6003, Vol. 66, No. 12
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Third Department of Pediatrics, Hippokration Hospital, University of Thessaloniki, GR-54642, Salonika, Greece,1 and Immunocompromised Host Section, Pediatric Oncology Branch, National Cancer Institute, Bethesda, Maryland 208922
Received 30 September 1997/Returned for modification 5 December 1997/Accepted 25 September 1998
Invasive aspergillosis is a serious complication in
immunocompromised patients. The effects of recombinant human tumor
necrosis factor alpha (TNF-
) on antifungal activities of human
neutrophils (polymorphonuclear leukocytes [PMNs]), human monocytes
(MNCs), and rabbit pulmonary alveolar macrophages (PAMs) against
Aspergillus fumigatus were studied. The percentage of
PMN-induced hyphal damage was increased after 30 min of incubation of
PMNs with 0.1 ng of TNF-
per ml at 37°C (P = 0.043). At 0.1 to 10 ng/ml, TNF-
also increased superoxide anion
(O2
) produced by PMNs in response to phorbol
myristate acetate, N-formylmethionyl leucyl phenylalanine,
and unopsonized hyphae (P < 0.01) but did not exert
any effect on PMN phagocytosis of conidia in the presence of
serum. By comparison, TNF-
induced only a slight increase in
O2
production by MNCs in response to
phorbol myristate acetate (P = 0.05) and no
concomitant increase in the percentage of MNC-induced hyphal damage.
Incubation of MNCs with TNF-
at 0.001 to 10 ng/ml for 2 days had no
effect on phagocytosis or conidiocidal activity. By contrast,
incubation of PAMs with TNF-
at 0.1 to 10 ng/ml for 2 days increased
phagocytosis of conidia (P = 0.03). Thus, TNF-
augments the capacity of PMNs to damage Aspergillus hyphae, possibly through enhanced oxidative mechanisms, and increases PAM
phagocytic activity against conidia. As such, TNF-
may have an
important role in host defense against aspergillosis, and
neutralization of its activity may be complicated by increased
susceptibility to aspergillosis.
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