CMV-encoded MHC class I homologues

Role of CMV-Encoded MHC Class I Homologues as Surrogate Inhibitory Ligands... 

Fig. 2A,B. Possible functions of the CMV-encoded MHC class I homologues models for inhibition of NK cell activity against CMV-infected cells. Three alternative models for the function of a CMV-encoded MHC class I homologue are depicted, involving either direct (A) or indirect (B) inhibition of NK cell activity. In all cases, it is proposed that the viral MHC class I homologue engages a cellular inhibitory receptor, which transduces inhibitory signals via the intracellular domain. In panel A, the inhibitory receptor is expressed on NK cells, resulting in direct inhibition of NK cell-mediated cytolysis of CMV-infected cells. In panel B, the inhibitory receptor is expressed on monocytes or dendritic cells (DC), resulting in indirect inhibition of NK cell activity by either (i) inhibition of production of cytokines which are required for optimal NK cell recruitment/activity or (ii) inhibition of direct stimulation of NK cells via cell-cell contact...

Kubota A, Kubota S, Farrell HE, Davis-Poynter N, Takei F (1999) Inhibition of NK cells by murine CMV-encoded class I MHC homologue, ml44. Cell Immunol 191 145-151 Lanier LL (1998) NK cell receptors. Annu Rev Immunol 16 359-393... 

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