NK cells provide helper signal for CD8+ T cells by inducing the expression of membrane-bound IL-15 on DCs.
NK cell recognition of cells that do not express or express low amounts of MHC class I molecules results not only in direct killing of target cells but also in the generation of specific T cell responses consequent to the induction of dendritic cell (DC) activation. While IL-12 production by NK cell-activated DCs is generally thought to play a critical role, a similar DC-mediated NK cell help has been reported also in IL-12-knockout mice. Here, we show that human NK cells can induce on DC surface membrane, via IFN-gamma secretion, the expression of high levels of IL-15. Remarkably, we show that DC expression of this membrane-bound form of IL-15, which is only partially associated with IL-15R molecules, is essential to promote specific CD8(+) T lymphocyte response in the absence of DC-derived IL-12.
Morandi
Barbara
B
Laboratory of Immunology and Biotherapy, Department of Human Pathology, University of Messina, Messina, Italy.
Mortara
Lorenzo
L
Carrega
Paolo
P
Cantoni
Claudia
C
Costa
Gregorio
G
Accolla
Roberto S
RS
Mingari
Maria Cristina
MC
Ferrini
Silvano
S
Moretta
Lorenzo
L
Ferlazzo
Guido
G