No abstract

Paralleling the activation of dorsal horn microglia after peripheral nerve injury is a significant expansion and proliferation of macrophages around injured sensory neurons in dorsal root ganglia (DRG). Here we demonstrate a critical contribution of DRG macrophages, but not those at the nerve injury site, to both the initiation and maintenance of the mechanical hypersensitivity that characterizes the neuropathic pain phenotype. In contrast to the reported sexual dimorphism in the microglial contribution to neuropathic pain, depletion of DRG macrophages reduces nerve injury-induced mechanical hypersensitivity and expansion of DRG macrophages in both male and female mice. However, fewer macrophages are induced in the female mice and deletion of colony-stimulating factor 1 from sensory neurons, which prevents nerve injury-induced microglial activation and proliferation, only reduces macrophage expansion in male mice. Finally, we demonstrate molecular cross-talk between axotomized sensory neurons and macrophages, revealing potential peripheral DRG targets for neuropathic pain management.

cancérologie, UMR892, UFR Médecine et Techniques médicales, Nantes, France NK-cell function is regulated by a balance between inhibitory and activating killer cell immunoglobulin-like receptors (KIR) that specifically recognize HLA class I molecules. Using KIR-specific mAb to discriminate between KIR2DS1 and KIR2DL1 receptors, we show that KIR2DS1 + NK cells are C2-alloreactive only from C2 À individuals. Moreover, using an in vitro model of NK-cell expansion, we show here that the frequency of KIR2DL1 + NK cells is significantly higher in the absence of C2 ligand on stimulator EBV-B cells than in its presence. This observation was made regardless of the presence or absence of the autologous C2 ligand, suggesting that the C2 À EBV-B stimulator cells used in this in vitro model could activate unlicensed KIR2DL1 + NK cells. In the case of KIR2DL1 + /S1 + genotyped individuals, KIR2DS1 + NK-cell frequency was increased after stimulation with C2 + compared with C2 À stimulator B cells, but only from C2 À individuals. Altogether, these data highlight the C2 alloreactivity of KIR2DS1 + NK cells that is only observed in C2 À individuals. These results provide new insights into the way in which NK KIR cell expansion might be regulated in an allogeneic environment.

Summary Natural killer (NK) cells are key components of the innate anti‐viral and anti‐tumour immune responses. NK cell function is regulated by the interaction of killer cell immunoglobulin‐like receptors (KIR) with human leucocyte antigen (HLA) class I molecules. In this study, we report on the generation of KIR‐specific antibodies allowing for discrimination between activating and inhibitory KIR. For this purpose, BALB/c mice were immunized with human KIR2DS2 recombinant protein. The precise specificity of KIR2DS2‐specific clones was determined on KIR‐transfected BW cells and KIR‐genotyped NK cells. When used in combination with EB6 (KIR2DL1/2DS1) or GL183 (KIR2DL2/2DL3/2DS2), two KIR‐specific monoclonal antibodies (mAbs), 8C11 (specific for KIR2DL1/2DL2/2DL3/2DS2) and 1F12 (specific for KIR2DL3/2DS2), discriminated activating KIR2DS1 (8C11− EB6+) from inhibitory KIR2DL1 (8C11+ GL183−) and KIR2DL2 (1F12− GL183+), while excluding the main HLA‐Cw‐specific KIR. Using these mAbs, KIR2DS1 was shown to be expressed on the surface of NK cells from all individuals genotyped as KIR2DS1+ (n = 23). Moreover, KIR2DS1 and KIR2DL1 were independently expressed on NK cells. We also determined the amino acid position recognized by the 8C11 and 1F12 mAbs, which revealed that some KIR2DL1 allele‐encoded proteins are not recognized by 8C11. Because most available anti‐KIR mAbs recognize both inhibitory and activating forms of KIR, these newly characterized antibodies should help assess the expression of activating and inhibitory KIR and their functional relevance to NK biology.