KIR2DL3 and severe acute respiratory syndrome: In this regard, the National Research Project for SARS, Beijing Group, has reported that in the cohort study of 221 patients with SARS who were admitted to hospitals, determining the total number of NK cells and CD158b+ (KIR2DL3) NK cells in 72 cases of severe SARS were significantly lower than those in mild cases (National Research Project for SARS, Beijing Group, 2004).