P03.01 Prevalence of CD112R+immune cells in normal lymphatic tissues, inflammation and the cancer microenvironment

Background CD112R is an inhibitory immune checkpoint receptor and a putative target for novel immune therapies, but little is known about its molecular epidemiology in healthy and diseased tissues. Materials and Methods To study the prevalence and expression level of CD112R+ immune cells, we analyzed more than 200 samples of normal lymphatic, inflamed and cancerous tissues in a microenvironment tissue microarray format (4 mm tissue spot diameter) and large sections using fluorescent multiplex immunohistochemistry. Results CD112R expression was detected at variable intensity levels in 47% of CD8+ cytotoxic lymphocytes, 49% of CD4+ T helper cells, 30% of FOXP3+ regulatory T helper cells and in 25% of CD56+ natural killer cells, but no expression was seen in CD11c+ dendritic cells and CD68+ macrophages. All analyzed compartments across normal and diseased tissues showed a small subset (CD8: 9±18%, CD4: 5±15%, FOXP3: 2±5%) of immune cells with supramaximal CD112R expression. The highest fraction of cells with supramaximal CD112R expression was found in the subset of CD8+ cytotoxic T cells in the Peyer’s patches of ileum (62%), the intergranuloma area of lymph node sarcoidosis (27%) and in ovarian cancer (37%). In cancerous tissues, the density and the fraction cytotoxic T cells with supramaximal CD112R expression was highly variable and ranged from 5% in bladder cancer to 3% in lung cancer and 36% in ovarian cancer. A high variability of the number of cells with supramaximal CD112R expression was also seen within every tumor entity. Conclusions In summary, our analysis shows that CD112R expression is abundant in various subsets of immune cells but identifies a small fraction of cells with exceedingly high CD112R levels. The widespread occurrence of CD112R+ cytotoxic T cells in the cancer microenvironment may suggest considerable opportunities for checkpoint inhibitors targeting CD112R. Disclosure Information N.C. Blessin: None. T. Mandelkow: None. E. Bady: None. C. Hube-Magg: None. R. Simon: None. G. Sauter: None. C. Fraune: None. M. Lennartz: None. K. Moller: None. D. Hoflmayer: None. S.A. Weidemann: None.