The orign of IKDC (Interferon producing killer dendritic cells)

The discovery of IKDC or Interferon producing Dendritic Cells in 2006 created enthusiasm in the immunology research (refrences 1 and 2). The DCs that can kill! what a link between innate and adaptive immunity. Interferons are involved in elimination of  viruses etc that are engulfed in the phagocytes. These interferons are secreted by NK or natural killer cells. The IKDCs were put along with other "hybrid cells" such as NKT cells, which share features with natural killer (NK) cells and T lymphocytes, and plasmacytoid dendritic cells (DCs), which combine the qualities of B cells and conventional DCs. IKDCs can function as NK cells by killing the cells lacking MHC molecules, like plasmacytoid DCs that produce interferon and like DCs that present antigen to conventional T cells. IKDCs not only secret type I and type II interferons to recognize and kill tumor cells effectively, but also express MHC-II molecules to present antigens. Thus, IKDCs are considered as important immunosurveilance cells for tumors, providing a link between innate and adaptive immunity. However, the developmental pathways of these cells were not fully understood.
However, Di Santos group from Pasteur Institute, Paris and Caminschi group from Australia studied the development of IKDCs and proved that these are not DCs but actually a subset of NK cells (Refrence 3 and 4). Generally mature NK cells in humans or mice express NK group 2, member D (NKG2D), CD161, NK-cell protein 46 (NKp46) and CD122. However, the expression of Ly49 family members, CD127, CD27 and KLRG1 (killer-cell lectin-like receptor subfamily G, member 1) in mice, and of KIRs (killer-cell immunoglobulin-like receptors), CD56 and CD16 in humans suggests heterogeneity within the mature NK-cell pool.


Suggested reading:
1. Chan et al, Interferon-producing killer dendritic cells provide a link between innate and adaptive immunity, Nature Medicine - 12, 207 - 213 (2006)
2. Taieb et al, A novel dendritic cell subset involved in tumor immunosurveillance, Nature Medicine - 12, 214 - 219 (2006)
3. Vosshenrich et al, CD11cloB220+ interferon-producing killer dendritic cells are activated natural killer cells.J Exp Med. Oct 29;204(11):2569-78 (2007)
4. Caminschi et al, Putative IKDCs are functionally and developmentally similar to natural killer cells, but not to dendritic cells.J Exp Med. Oct 29;204(11):2579-90 (2007)
5. Huntington et al, Developmental pathways that generate natural-killer-cell diversity in mice and humans, Nature Reviews Immunology 7, 703-714 (2007)