Background Despite numerous advances in the identification of risk factors for the development of severe coronavirus disease 2019 (COVID-19), factors that promote recovery from COVID-19 remain unknown. Natural killer (NK) cells provide innate immune defense against viral infections and are known to be activated during moderate and severe COVID-19. Killer immunoglobulin-like receptors (KIR) mediate NK cell cytotoxicity through recognition of an altered MHC-I expression on infected target cells. However, the influence of KIR genotype on outcome of patients with COVID-19 has not been investigated so far. We retrospectively analyzed the outcome associations of NK cell count and KIR genotype of patients with COVID-19 related severe ARDS treated on our tertiary intensive care unit (ICU) between February and June 2020 and validated our findings in an independent validation cohort of patients with moderate COVID-19 admitted to our tertiary medical center. Results Median age of all patients in the discovery cohort ( n = 16) was 61 years (range 50–71 years). All patients received invasive mechanical ventilation; 11 patients (68%) required extracorporeal membrane oxygenation (ECMO). Patients who recovered from COVID-19 had significantly higher median NK cell counts during the whole observational period compared to patients who died (121 cells/µL, range 16–602 cells/µL vs 81 cells/µL, range 6–227 cells/µL, p -value = 0.01). KIR2DS5 positivity was significantly associated with shorter time to recovery (21.6 ± 2.8 days vs. 44.6 ± 2.2 days, p -value = 0.01). KIR2DS5 positivity was significantly associated with freedom from transfer to ICU (0% vs 9%, p -value = 0.04) in the validation cohort which consisted of 65 patients with moderate COVID-19. Conclusion NK cells and KIR genotype might have an impact on recovery from COVID-19. Supplementary Information The online version contains supplementary material available at 10.1186/s40635-021-00409-4.
【저자키워드】 COVID-19, SARS-CoV-2, ARDS, intensive care unit, NK cells, KIR, 【초록키워드】 viral infection, intensive care, severe COVID-19, NK cell, cytotoxicity, outcome, risk factor, ICU, extracorporeal membrane oxygenation, Cohort, Patient, Genotype, ECMO, age, Time to recovery, expression, moderate, association, innate immune, MHC-I, target cells, natural, Factor, supplementary material, severe coronavirus disease, severe ARDS, transfer, validation cohort, Defense, Cell, independent, Result, analyzed, died, significantly, investigated, required, median, treated, activated, promote, significantly higher, invasive mechanical, Killer immunoglobulin-like receptor, KIR2DS5, patients with COVID-19, patients with moderate, 【제목키워드】 coronavirus disease, receptor,