Characterization of the defective interaction between a subset of natural killer cells and dendritic cells in HIV-1 infection

J. Exp. Med., 2006, 203:2339-2350

Speaker: 林妍君                             Date: 2006/12/13, 15:10~16:00

Commentator: 凌斌老師                       Place: Room 601

Abstract:

Natural killer (NK) cells are specialized lymphocytes that act the first line in defense of tumor and viral infection, and also play an important role in initiation and regulation of adapted immunity. Another immune cell which is the liaison of innate and adapted immune system is the dendritic cell (DC). DC cells have been reported to activate NK cell at the site of inflammation. Activated NK cells can regulate the differentiation of DC cells by promoting maturation of DC cell, or by elimination of immature dendritic cell (iDC). Such interaction is the so-called cross-talking of NK-DC¹. However, it was found that an unusual subset of CD56^neg/CD16^pos NK cells were expanded in HIV-1 infected viremic comparing with aviremic patient². In addition, matured DC cells in HIV-1 infected patient also have several functional defects although they may express normal maturation surface marker. Therefore, the authors like to study whether the defect there is via cross-talk in HIV-1 infected patient. They found that viremic but not aviremic patients have abnormality in NK-DC interaction and cytokine secretion, as well as abnormality in NK cell-mediated killing of iDC. The defect via elimination of iDC was that level of activating NK cell receptors. The markedly impairment of expression and function of NKp30 and TNF-related apoptosis-inducing ligand(TRAIL), particularly on CD56^neg NK cell subset were responsible for the defect via NK cell-mediated lysis of iDC. This finding suggests that an impairment of NK-DC cross-talk may be one of the reasons that cause NK cell dysfunction and interfere with an effective immune response.

Reference:

1.      Mariapia A, et al. Close encounters of different kinds: dendritic cells and NK cells take centre stage. Nat. Rev. Immunol., 2005, 5:112-124.

2.      Mavilio A, et al. Natural killer cells in HIV-1 infection: Dichotomous effects of viremia on inhibitory and activating receptors and their functional correlates. Proc. Natl. Acad. Sci., 2003, 100:15011-15016.