Impact Of an Immune Modulator Mycobacterium-w On Adaptive Natural Killer Cells and Protection Against COVID-19

Abstract

SummaryThe kinetics of NKG2C+ adaptive natural killer (ANK) cells and NKG2A+inhibitory NK (iNK) cells with respect to the incidence of SARS-CoV-2 infection were studied in a cohort of health-care workers following administration of heat killed Mycobacterium w (Mw group) in comparison to a control group. COVID-19 infection correlated with a lower NKG2C+ANK cells at baseline. NKG2C+ANK cells at baseline did not differ, but there was a significant upregulation of NKG2C expression and cytokine release in the Mw group (p=0.0009), particularly in those with lower baseline NKG2C expression (<15%), along with marked downregulation of NKG2A+iNK cells (p<0.0001), and an increase in the NKG2C+ANK/NKG2A+iNK ratio. This translated to a significant reduction in COVID-19 and its severity in the Mw group. No impact was observed on T cell subsets. Mw was observed to have a salutary impact on the ANK cell profile which might have provided protection against COVID-19 over a prolonged period in a non-immune high-risk population.