Characterization of Human Natural Killer Cell Receptors Recognizing Aspergillus fumigatus

Ref ID: 19601

Author:

S Brueggemann1*, AL Schmitt1, H Einsele1, J Loeffler1

Author address:

1Medical Clinic and Policlinic II, University Hospital Wuerzburg, Wuerzburg, Germany

Full conference title:

6th Advances Against Aspergillosis 2014

Abstract:

Purpose:
Natural killer (NK) cell recruitment by chemokines is a fundamental host defense mechanism
during invasive aspergillosis in neutropenic mice. Mice double depleted in neutrophils and NK cells
showed a twice fold mortality compared to neutropenic mice with normal NK cells. However, the
exact mechanisms of the interaction between human NK cells and A. fumigatus are still unknown.
Previously, our group was able to show that NK cells exhibit a cytotoxic effect against A. fumigatus
germtubes by releasing IFNγ which induces fungal damage. Here, we further characterize the
interaction of human NK cells and A. fumigatus germtubes to identify potential pathogen recognition
receptors (PRRs) on the NK cell surface.
Methods:
NK cells were isolated from PBMCs of healthy donors by negative selection (MACS) and treated
with Pro-Leukine overnight. NK cells were then either stimulated with A. fumigatus germtubes
(MOI 0.5), or with IL15 and Pro-Leukine (positive control) or left untreated for 3h, 6h, 9h and
12h respectively, followed by analyses of NK cell activating receptors. Different pretreatments
(Untreated, Pro-Leukine or IL2 pretreated) of NK cells and stimulation with different NK cell targets
(K562, LPS, inactivated Candida (C.) albicans and inactivated A. fumigatus germtubes) were used
to confirm receptor deregulation.
Results:
After stimulation of NK cells with A. fumigatus, the expression of the activation markers CD69
and CD137 significantly increased. Interestingly, a time dependent downregulation of the NK cell
characterization marker CD56 was observed on the NK cell surface. However, this downregulation
was not due to induced apoptosis in these cells. Furthermore, in highly activated NK cells the
CD56 positive cells were reduced to a lesser extent than in untreated and Pro-Leukine pretreated
cells. Treatment of NK cells with different targets such as K562, LPS, inactivated C. albicans and
inactivated A. fumigatus revealed no reduction of CD56 on the surface of NK cells. In addition,
the activation receptors NKp30, NKp44, NKG2D showed only a slight reduction in Pro-Leukine
pretreated NK cells stimulated with A. fumigatus compared to the negative control.
Conclusion:
Treatment of NK cells with A. fumigatus induces NK cell activation and leads to a stringent reduction
of CD56 on the cell surface. This downregulation was not induced by apoptosis of these cells and
it was shown that the decrease of CD56 positive cells was only induced by living A. fumigatus
germtubes while it was not present on NK cells stimulated with K562, LPS, inactivated C. albicans
and inactivated A. fumigatus germtubes. These results suggest a role of CD56 in the recognition
of A. fumigatus. Future experiments with blocking antibodies of CD56 and the NK cell activation
receptors should provide an indication whether NK cell activation is also induced by CD56 or not.
Fluorescence microscopy analyses will be performed to monitor localization of A. fumigatus and
binding to CD56. These experiments will help to understand the interaction of human NK cells
and A. fumigatus and identify the potential PRRs.

Abstract Number: 126

Conference Year: 2014

Link to conference website: http://www.AAA2014.org

New link: NULL

Conference abstracts, posters & presentations

Showing 10 posts of 17325 posts found.

  • Title

    Author

    Year

    Number

    Poster