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Infect. Immun., 03 1997, 971-977, Vol 65, No. 3
S Frosch, D Kuntzlin and B Fleischer
T-cell-mediated immune responses are essential for protection against
infection with the protozoan Trypanosoma cruzi. In this study, we
investigated the influence of infection of murine macrophages with T. cruzi
on costimulatory signals for T lymphocytes provided by these cells. We
demonstrate that bone marrow-derived macrophages (BMMph) selectively and
strongly upregulate expression of B7-2 molecules after infection, while the
expression of other costimulatory molecules such as B7-1, intercellular
adhesion molecule 1, lymphocyte function- associated antigen 3, and
heat-stable antigen is not significantly affected. Infection by live
trypanosomes was required. As a consequence of the strong B7-2
upregulation, the infected macrophages are able to induce proliferation of
splenic CD4+ T cells in the presence of anti- CD3 antibodies with much
higher efficiency than uninfected macrophages. Costimulation could be
inhibited by an antibody to B7-2. Furthermore, costimulatory activity for
established T-cell clones of Th1 and Th2 phenotype was also strongly
enhanced in BMMph by infection with T. cruzi. Th1 cells stimulated either
via anti-CD3 antibodies or via specific antigen proliferated with higher
efficiency in the presence of infected macrophages than in the presence of
uninfected cells. BMMph stimulated with gamma interferon (IFN-gamma),
expressing elevated levels of B7-2 molecules, are also able to enhance Th1
cell proliferation, which was highest, using macrophages which were
infected and in parallel were stimulated with IFN-gamma. Noteworthy, for
cloned Th2 cells, the mechanism of costimulation differed, because
costimulation of Th2 cells was not dependent on B7-2 upregulation but was
due to secretion of interleukin-1alpha. These findings demonstrate that
infection of macrophages with T. cruzi transforms the macrophage into a
potent costimulatory cell based on the induction of two different
costimulatory activities.
Copyright © 1997, American Society for Microbiology
Infection with Trypanosoma cruzi selectively upregulates B7-2 molecules on macrophages and enhances their costimulatory activity
Department of Immunology, Bernhard Nocht-Institute for Tropical Medicine, Hamburg, Germany. Stefanie_Frosch@magicvillage.de
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