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Accessory function for NK1.1+ natural killer cells producing interferon-gamma in xenospecific cytotoxic T lymphocyte
1Cellular Cytotoxicity Laboratory, The Austin Research Institute, Heidelberg, Victoria, Australia.
Background:
We have previously demonstrated that xenospecific cytotoxic T lymphocyte (CTL) differentiation requires accessory function by NK1.1+ cells, yet the mechanism by which NK1.1+ cells support CTL generation had not been elucidated.
Methods:
An established model in which mice generate a strong local popliteal lymph node CTL response to footpad immunizations with human tumor cells was used. Mice depleted of NK1.1+ cells fail to mount a maximal xenospecific CD8+ CTL response. The xenospecific CTL response in anti-NK1.1 monoclonal antibody-depleted mice could be completely restored if mice were coinoculated with human tumor cells (the xenoantigen) and xenoantigen-stimulated syngeneic natural killer (NK) cells from wild-type or perforin-deficient mice. By contrast, NK1.1+ cells from interferon-gamma-deficient mice did not restore the maturation of xenospecific CTL in anti-NK1.1 monoclonal antibody-treated mice. Depletion of NK1.1+ cells in vivo from both wild-type and Jalpha281-deficient mice (which lack Valpha14 NK1.1+ T cells) abrogated the generation of xenospecific CTL, however, untreated Jalpha281-deficient mice mounted a normal xenogeneic response.
Conclusions:
These data indicate that local NK cell production of interferon-gamma at the site of challenge is an important stimulus for generating xenospecific CTL in local draining lymph nodes and that Valpha14 NK T cells play little or no regulatory function in this response.