Natural killer cell (NKc)-based therapies offer promising outcomes in patients with tumors, but they could improve with appropriate selection of donors and optimization of methods to expand NKcs in vitro. Education through licensing interactions of inhibitory killer cell immunoglobulin-like receptors (iKIR) and NKG2A with their cognate HLA class-I ligands optimizes NKc functional competence. This work has evaluated the role of licensing interactions in NKc differentiation and the survival of cancer patients. We have analyzed KIR and KIR-ligand genes, and the expression of activating (CD16 and DNAM-1/CD226) and inhibitory (NKG2A and iKIRs) receptors on peripheral blood NKcs in 621 healthy controls and 249 solid cancer patients (80 melanoma, 80 bladder, and 89 ovarian). Licensing interactions upregulated the expression of activating CD226, reduced that of iKIR receptors, and shifted the CD226/iKIR receptor ratio on NKc membranes to activating receptors. A high tumor burden decreased CD226 expression, reduced the ratio of CD226/iKIR, and negatively affected patient survival. The progression-free survival (38.1 vs. 67.0 months, P < 0.002) and overall survival (56.3 vs. 99.6 months, P < 0.00001) were significantly shorter in patients with lower expression of CD226 on NKcs. Hence, transformed cells can downmodulate these licensing-driven receptor rearrangements as a specific mechanism to escape NKc immune surveillance. Our results suggest the importance of the CD226/ iKIR receptor ratio of NKcs induced by licensing interactions as critical determinants for solid cancer immune surveillance, and may provide predictive biomarkers for patient survival that may also improve the selection of donors for NKc immunotherapy. Cancer Immunol Res; 6(12); 1537-47. Ó2018 AACR. NKcs can also express up to 6 different activating KIR (aKIRs): KIR2DS1-5 and KIR3DS1. Only the interactions between KIR2DS1/HLA-C2 allotypes (15, 16), KIR2DS4/HLA-A Ã 1102, and to a limited number of HLA-C1/-C2 alleles and KIR3DS1 Ã 014/HLA-Bw4 (17-19) have been reported, although

L3¡ (20% vs. 83%, p < 0.00001) as well as KIR3DL1 ¡ (23% vs. 82%, p < 0.00001) genotypes had a dramatic negative impact on the 3-y progression-free survival (PFS), particularly in patients with lowtumor burden. Remarkably, myeloma-PCs, compared to K562 and other hematological cancers, showed substantial over-expression of HLA-I ("increasing-self" instead of missing-self), including HLA-C, and mild expression of ligands for NKc activating receptors (aRec) CD112, CD155, ULBP-1 and MICA/B, which apparently renders myeloma-PCs susceptible to lysis mainly by licensed NKc. KIR2DL1patients (with no conventional iKIR2D/HLA-C licensing interactions) lyse K562 but barely lyse myelomaPCs (4% vs. 15%; p < 0.05, compared to controls). These results support a model where immunosurveillance of no-missing-self cancers, e.g., myeloma, mainly depends on NKc licensing.

Background Etiopathogenesis of the clinical variability of the coronavirus disease 2019 (COVID-19) remains mostly unknown. Here we investigate the role of Killer-cell Immunoglobulin-like receptor (KIR)/Human Leukocyte Antigen Class-I (HLA-I) interactions in the susceptibility and severity of COVID-19. Methods KIR and HLA-I genotyping and NK cell (NKc) receptors immunophenotyping in 201 symptomatic patients and 210 non-infected controls. Results NKcs with a distinctive immunophenotype, suggestive of recent activation (KIR2DS4 low CD16 low CD226 low CD56 high TIGIT high NKG2A high), expanded in patients with severe COVID-19. This was associated with a higher frequency of the functional A-telomeric activating KIR2DS4 in severe than mild/moderate patients and controls (83.7%, 55.7% and 36.2%, p&lt;7.7x10 -9). In mild/moderate patients HLA-B*15:01 was associated with higher frequencies of activating B-telomeric KIR3DS1 compared to patients with other HLA-B*15 subtypes and non-infected controls (90.9%, 42.9% and 47.3%, p&lt;0.002, Pc=0.022). This strongly suggests that HLA-B*15:01 specifically presenting SARS-CoV-2 peptides could form a neo-ligand interacting with KIR3DS1. Similarly, a putative neo-ligand for KIR2DS4 could arise from other HLA-I molecules presenting SARS-CoV-2 peptides expressed on infected/activated lung antigen presenting cells. Conclusions Our results support a crucial role of NKcs in the clinical variability of COVID-19 with specific KIR/Ligand interactions associated to disease severity.

Therapies using NK cells (NKc) expanded/activated ex vivo or stimulated in vivo with new immunostimulatory agents offer alternative opportunities for patients with recurrent/ refractory tumors, but relevant biomarkers to guide the selection of patients are required for optimum results. Overall survival of 249 solid cancer patients was evaluated in relation to the genetics and/or the expression on peripheral blood NKcs of inhibitory and activating killer-cell immunoglobulin-like receptors (iKIR and aKIR, respectively), HLA class I ligands, CD226 (also known as DNAM-1), and NKG2A. Compared with patients with higher expression, patients with low expression of CD226 on total NKcs showed shorter mean overall survival (60.7 vs. 98.0 months, P < 0.001), which was further reduced in presence of telomeric aKIRs (KIR2DS1-DS5 and/or KIR3DS1, 31.6 vs. 96.8 months, P < 0.001). KIR2DL2/S2 þ , KIR3DL1 þ , KIR2DL1 þ , and KIR2DL3 þ NKc subsets in the presence of their cognate ligands primarily contributed to shortening patients' overall survival by increasing the sensitivity to CD226 downmodulation in aKIR-rich telomeric genotypes. In patients with high tumor burden who died during the follow-up period, aKIR-rich telomeric genotypes were associated with: (i) specific downmodulation of CD226 on educated NKcs but not on CD8 þ T cells or uneducated NKcs, (ii) lower expression of CD226 and higher expression of NKG2A on aKIR þ NKcs, and (iii) lower numbers of total CD56 dim NKcs. The reduced expression of CD226 on NKcs with aKIR-rich genotypes may be a biomarker indicative of NKc hyporesponsiveness in patients that could benefit from new NKc immune-stimulatory therapies.

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