Poster Presentation Australasian Society for Immunology Annual Scientific Meeting 2014

Characterising natural killer cell subset responses to a Herpes Simplex Virus lipopeptide (#261)

Naomi Truong 1 2 , Min Kim 1 2 , Weiguang Zeng 3 , David C Jackson 3 , Anthony L Cunningham 1 2
  1. Sydney Medical School, University of Sydney, Sydney, NSW, Australia
  2. Westmead Millennium Institute, Westmead, NSW, Australia
  3. Department of Microbiology and Immunology, University of Melbourne, Parkville, VIC, Australia

Human natural killer (NK) cells in circulation are categorised into two subsets. The majority (>95%) are CD56dimCD16+, characterised as highly cytolytic against infected target cells. A small proportion (<5%) are CD56brightCD16-/dim, which have decreased cytolytic capacity, but markedly increased production of cytokines such as Interferon-γ. We are investigating Herpes Simplex Virus (HSV) vaccine design using a Toll-like receptor 2 (TLR-2) stimulating lipid-conjugated HSV peptide, “Pam2Cys-30”. Previously, we observed that CD4 T lymphocyte responses to Pam2Cys-30 were enhanced by the presence of NK cells in coculture with dendritic cells (DC) and CD4 T lymphocytes. Furthermore, NK cells were directly activated by Pam2Cys-30 and could activate CD4 T lymphocytes in the absence of other antigen presenting cells. Therefore, we investigated Pam2Cys-30 activation of NK cells, to examine and compare responses between the NK cell subsets. When NK cells were stimulated by Pam2Cys-30 and cultured overnight, both CD56bright and CD56dimCD16+ NK cell subsets were activated as shown by CD69 expression, however, expression was higher in CD56dimCD16+ cells. After cell sorting, both subsets were activated independently of each other when stimulated by Pam2Cys-30. We also observed that in the CD56dimCD16+ population, stimulus by Pam2Cys-30 triggered a significant proportion of cells to downregulate CD16. This CD56dimCD16- population was highly activated as shown by high expression levels of CD69 and HLA-DR. Intracellular cytokine staining demonstrated that the CD56dimCD16- population had a higher percentage of IFN-γ+ cells than the other NK cell subsets. Determining the mechanism by which Pam2Cys-30 is taken up by NK cells and induces phenotypic and functional changes in each subset is ongoing work. Characterising how NK cells respond to Pam2Cys-30 is important for understanding their contribution to T cell activation and demonstrates the importance of considering NK cells in addition to DC when designing novel vaccine candidates.