018 Dysregulation of natural killer cell activity in dermatomyositis

Natural killer (NK) cell number and cytotoxicity are decreased in the blood of patients with a wide range auto-immune conditions. However, role NK cells dermatomyositis (DM) has not been explored. To quantify activity, we utilized signature score, summing standardized z-scores previously validated NK-specific gene set: Nkp46, CD160, KLRC3, CD244, KLRF1, KLRC1, GNLY, PRF1, XCL2, IL18RAP. Upregulation downregulation were defined as scores above 2sd below -2sd, respectively. The score DM (n= 201) was on average -6.44sd mean healthy controls (p=0.0045, t-test) whereas skin (n=181) 40.24sd (p= 2.75E-18, t-test). inversely associated disease activity measured by CDASI age onset 0.02 0.002, respectively, multivariate linear regression). In addition, longitudinal samples from 73 showed significant inverse correlation between temporal changes (p=0.038, regression).136 biopsies (n=181, 75.14%) had elevated signature, lesional twice much expression non-lesional 4.37E-06, There no signatures same patients. Elevated increased dyskeratotic keratinocytes, basal vacuolization, vascular dilatation histopathology (χ2= 9.72, p= 0.021; χ2= 12.01, p=0.017; χ2=10.19, p=0.017, respectively). tissue did significantly differ among autoantibody groups. summary, our study shows consistent upregulation This is keratinocyte death, highlighting potential for disease.