KIR2DL3 and severe acute respiratory syndrome: More importantly, this study has shown that percentage of CD158b+ NK cells in patients with M pneumonia infection and SARS patients (with positive clinical criteria and negative anti-SARS coronavirus) wasn’t significantly altered as compared to the percentages of NK cells in SARS cases (with positive for both clinical criteria and anti-SARS coronavirus), which indicates that the NK cells monitoring should be helpful in differentiating true SARS from false SARS and M pneumonia infection.