Brucellosis 2003 proceedings - PHIDIAS

Short Oral Communications
Immunology, pathogenesis and host-pathogen interaction
PO6- THE ROLE OF HUMAN GAMMA 9 DELTA2 T CELLS IN INNATE IMMUNITY
AGAINST INTRACELLULAR Brucella.
Jane Oliaro, Sherri Dudal, Janny Liautard, Jean-Baptiste Andrault, Jean-Pierre Liautard and Virginie
Lafont. Institut National de la Santé et de la Recherche Médicale Unité 431, Laboratoire de
Microbiologie et Pathologie Cellulaire Infectieuse, Université de Montpellier II, Montpellier, France.
Human gamma 9 delta2 T cells can contribute to immunity against intracellular
pathogens through the release of soluble factors and direct cytotoxic activity against
infected host cells. Here, we have used a co-culture model of human gamma 9 delta
2 T cells and B. suis-infected autologous macrophages to clarify the mechanisms
used by gamma 9 delta 2 T cells. We found that: 1) gamma 9 delta 2 T cells,
cultured in the presence of B. suis-infected macrophages, produce soluble factor(s)
that have an effect on bacterial numbers; 2) Proteins of the granule exocytosis
pathway are not responsible for this effect; 3) Fas-activated macrophage death is
associated with a reduction in intracellular Brucella; 4) IFN-gamma and TNF-alpha,
produced by gamma 9 delta 2 T cells, have no effect on bacterial numbers; 5) Pretreatment
of macrophages with gamma 9 delta 2 T cell supernatant prior to infection,
results in a dramatic reduction in the number of intracellular bacteria; and 6) Soluble
factors produced by gamma 9 delta 2 T cells can directly affect Brucella viability in
the absence of host cells. Our results suggest that gamma 9 delta 2 T cells can
orchestrate an immediate innate immune response that benefits the host by limiting
the spread of intracellular pathogens.
PO7- DO CD8 T CELLS HAVE A ROLE IN CONTROLLING Brucella abortus
INFECTIONS?.
R. Goenka, M. Parent, and C.L. Baldwin. Department of Veterinary and Animal Sciences, University
of Massachusetts, Amherst, MA 01003. USA.
Acquired resistance to Brucella abortus clearly involves both antibodies and T
cells initially following infection, however experimental evidence indicates that T cells
are the component of the immune system involved in clearance. Moreover, the T cell
cytokine interferon-g is crucial for survival of a brucella infection in the murine model.
The relative contribution of CD4 and CD8 T cells to control and clearance of the
infection remains unclear. Several studies evaluating control of the vaccine strain 19
injected intravenously suggest CD8 T cells are crucial for control of this attenuated
strain. By contrast, one study shows a similar role for CD8 and CD4 T cells in control
of the virulent field strain B. abortus 2308 injected intravenously while a study from
our lab shows no role for CD8 T cells when 2308 is injected intraperitoneally. Here
we sought to resolve whether the difference in control by different subpopulations of
T cells reflected the virulence of the brucella strain or the route of infection. Studies
compared the role of major histocompatiblity complex (MHC) class I restricted CD8 T
cells with that of MHC class II restricted CD4 T cells following intravenous or
intraperitioneal injection of strain 19 infections by using knock-out strains of mice
lacking expression of class I or class II molecules. These studies are important for
vaccine design since stimulation of CD4 and CD8 T cells have very different
requirements due to differences in presentation of antigenic peptides on class I or
class II MHC molecules.
Brucellosis 2003 International Research Conference
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