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Infection and Immunity, September 1998, p. 4324-4330, Vol. 66, No. 9
Microbiology Section, Department of
Experimental Medicine and Biochemical Sciences, University of Perugia,
06122 Perugia, Italy1;
Albert Einstein
College of Medicine, Bronx, New York 104612; and
Department of Microbiology, University of Nevada School of
Medicine, Reno, Nevada 89557-00463
Received 28 January 1998/Returned for modification 31 March
1998/Accepted 1 July 1998
In a previous paper we demonstrated that human polymorphonuclear
cells (PMN) in the presence of normal human serum (NHS) secrete proinflammatory cytokines in response to Cryptococcus
neoformans or its major capsular component, glucuronoxylomannan
(GXM). The hypothesis that activation of the complement system could be
responsible for the observed phenomenon is supported by the fact that
encapsulated and acapsular C. neoformans isolates are
activators of the complement system and, in particular, large
encapsulated isolates are powerful activators. In the present study we
demonstrate that (i) interleukin-8 (IL-8) release in response to
acapsular or encapsulated strains of C. neoformans is
significantly reduced in the presence of heat-inactivated serum rather
than NHS and is completely abrogated in the absence of human serum;
(ii) GXM-induced IL-8 release is strictly dependent on the presence of
NHS, is inhibited by specific antibodies to either C3a and C5
complement components, and is completely abrogated by the combined use
of these antibodies; (iii) the addition of purified C3a and C5a
directly stimulates IL-8 release by PMN; and (iv) monoclonal antibody
to GXM in combination with GXM or encapsulated C. neoformans potentiates IL-8 release by PMN. These data shed light
on the mechanism involved in GXM-induced IL-8 secretion by PMN, provide
an additional potential role for complement in the control of C. neoformans infections, and suggest a complex interplay between
the complement system, humoral immunity, and cytokine regulation.
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Involvement of C3a and C5a in Interleukin-8
Secretion by Human Polymorphonuclear Cells in Response to Capsular
Material of Cryptococcus neoformans
*
Corresponding author. Mailing address: Microbiology
Section, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Via del Giochetto, 06122 Perugia, Italy. Phone:
39-75-585-3407. Fax: 39-75-585-3400. E-mail:
vecchiar{at}unipg.it.
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