Engagement of NKG2D by cognate ligand or antibody alone is insufficient to mediate costimulation of human and mouse CD8+ T cells

LIR Ehrlich, K Ogasawara, JA Hamerman… - The Journal of …, 2005 - journals.aai.org
LIR Ehrlich, K Ogasawara, JA Hamerman, R Takaki, A Zingoni, JP Allison, LL Lanier
The Journal of Immunology, 2005journals.aai.org
CD8+ T cells require a signal through a costimulatory receptor in addition to TCR
engagement to become activated. The role of CD28 in costimulating T cell activation is well
established. NKG2D, a receptor found on NK cells, CD8+ αβ-TCR+ T cells, and γδ-TCR+ T
cells, has also been implicated in T cell costimulation. In this study we have evaluated the
role of NKG2D in costimulating mouse and human naive and effector CD8+ T cells.
Unexpectedly, in contrast to CD28, NKG2D engagement by ligand or mAb is not sufficient to …
Abstract
CD8+ T cells require a signal through a costimulatory receptor in addition to TCR engagement to become activated. The role of CD28 in costimulating T cell activation is well established. NKG2D, a receptor found on NK cells, CD8+ αβ-TCR+ T cells, and γδ-TCR+ T cells, has also been implicated in T cell costimulation. In this study we have evaluated the role of NKG2D in costimulating mouse and human naive and effector CD8+ T cells. Unexpectedly, in contrast to CD28, NKG2D engagement by ligand or mAb is not sufficient to costimulate naive or effector CD8+ T cell responses in conventional T cell populations. While NKG2D did not costimulate CD8+ T cells on its own, it was able to modify CD28-mediated costimulation of human CD8+ T cells under certain contitions. It is, therefore, likely that NKG2D acts as a costimulatory molecule only under restricted conditions or requires additional cofactors.
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