CD8?? homodimers function as a coreceptor for KIR3DL1.

ABSTRACT: Cluster of differentiation 8 (CD8) is a cell surface glycoprotein, which is expressed as 2 forms, ?? homodimer or ?? heterodimer. Peptide-loaded major histocompatibility complex class I (pMHC-I) molecules are major ligands for both forms of CD8. CD8?? is a coreceptor for the T cell receptor (TCR) and binds to the same cognate pMHC-I as the TCR, thus enabling or augmenting T cell responses. The function of CD8?? homodimers is largely unknown. While CD8?? heterodimer is expressed exclusively on CD8+ T cells, the CD8?? homodimer is present in subsets of T cells and human natural killer (NK) cells. Here, we report that the CD8?? homodimer functions as a coreceptor for KIR3DL1, an inhibitory receptor of NK cells that is specific for certain MHC-I allotypes. CD8?? enhances binding of pMHC-I to KIR3DL1, increases KIR3DL1 clustering at the immunological synapse, and augments KIR3DL1-mediated inhibition of NK cell activation. Additionally, interactions between pMHC-I and CD8?? homodimers regulate KIR3DL1+ NK cell education. Together, these findings reveal another dimension to the modulation of NK cell activity.

SUBMITTER: Geng J 

PROVIDER: S-EPMC6731649 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature