{'fraction_non_alphanumeric': 0.03286384976525822, 'fraction_numerical': 0.011997913406364111, 'mean_word_length': 4.938080495356037, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The impact of SARS-CoV-2 peptides on activation of NK cells

BACKGROUND: NK cells, alone with T lymphocytes, have a high antiviral activity. Exploring the contribution of NK cells in fighting SARS-CoV-2 infection may promote the development of appropriate treatments for COVID-19. Previously, NK cell response was considered nonspecific, provided by a combination of signals from activating and inhibitory receptors. Currently, the existence of certain subpopulations of antigen-specific, or adaptive, NK cells has been shown. 
AIM: To evaluate the functional response of NK cells induced by SARS-CoV-2 peptides. 
MATERIALS AND METHODS: The functional response of NK cells to SARS-CoV-2 peptides was determined by their degranulation (surface CD107a expression) and IFN production levels, and by the activation degree (HLA-DR expression level). Volunteers who recovered from COVID-19 participated in the study, and immune cells from a healthy volunteer without SARS-CoV-2-specific antibodies were used as controls. 
RESULTS: NK cells from individuals who had recovered from COVID-19, in contrast to a donor who had not been infected, showed a higher level of IFN production in response to SARS-CoV-2 peptides, compared with control samples. The level of degranulation of NK cells from donors previously infected with SARS-CoV-2 was higher than in the corresponding control. The proportion of activated NK cells obtained from recovered donors was also higher in samples stimulated with SARS-CoV-2 peptides. 
CONCLUSIONS: We have demonstrated the activation of NK cells obtained from people who had previously recovered from COVID-19 in response to SARS-CoV-2 peptide antigens in cultures of peripheral mononuclear cells in vitro. This study reveals the possibility for further investigation of antigen-specific NK cells in COVID-19 disease. The use of such cells could help develop treatments for SARS-CoV-2 infection.