SELL and COVID-19: For further analysis, NKT cells of 202 COVID-19 patients and 28 controls were grouped into 6 cell subtypes, including NKT_CD4_CD40LG, NKT_CD4_TIM3_CD62L, NKT_CD8, NKT_CD8_CD40LG, NKT_CD8_TIM3, and NKT_DN_ITGAX (Figure 3A).