KLRK1 and COVID-19: Similar results were obtained when the same analysis was performed to study the expression of NKG2D in NKT cells with values of 99,577 (81,873–107,068) in healthy controls vs. 62,247 (45,737–82,792) in COVID-19 patients (Table 1), p < 0.001; 60611 (42,408–76,618) in non-hospitalized patients (p < 0.001); and 70,436 (56,316–96,138) in severe COVID-19 patients, p = 0.009 (Figure 2B).