1044. Identification and Characterization of an Unconventional NK Subset in COVID-19

Abstract Background Coronavirus Disease 2019 (COVID-19) caused by the SARS-CoV-2 virus is associated with dysregulation in innate immune response including NK cells. cells are integral against viral infections. Canonical classified as CD56dim CD16+ and CD56bright CD16-. An unconventional subset of CD16- has previously been identified COVID-19 that not present other Here we characterize phenotypic changes patients severe work towards determining functional status this subset. Methods Peripheral blood mononuclear (PBMCs) plasma were isolated from healthy donors (n=5) on Extra Corporeal Membrane Oxygenation (ECMO) (n=15). Primary stimulated vitro or donors. Flow cytometry was used to phenotype A separate cohort PBMC samples (n=7) requiring hospitalization for underwent Cellular Indexing Transcriptomes Epitopes Sequencing (CITE-Seq) analysis. Results The expanded PBMCs compared controls. CITE-Seq demonstrated without surface CD16 clustered separately based transcriptional profiling did express FCGR3A at translational level. Stimulation recapitulated loss primary human led increased activity Caspase 3/7. Figure 1.NK shift CD16-subset COVID-19. a) Representative gating cell subsets Cytometry patient peripheral (PBMCs). b) Percentage total belonging a particular between donor (n=4) (n=8). Data points represent an individual sample. Error bars standard deviation mean. Differences groups analyzed using two tailed t-test. *: p< 0.05, ns: significant 2.NK after stimulation analysis plasma. b)Relative change percentage (n=6)and (n=15) conditions. mean difference two-tailed T-test. **: 0.01, ***: 0.001, significant. Conclusion We demonstrate nonclassical population replicate vitro. Reproduction vivo system will allow additional studies state presence may reflect dysregulated immunopathogenesis Disclosures All Authors: No reported disclosures.