KLRK1 and systemic inflammatory response syndrome: Except for higher proportion of KIR3DL1+ NK cells, no difference in expression of either activating (i.e., CD16, NKp30, NKp46, and NKG2D) or inhibitory membrane receptors (i.e., KIR, NKG2A) was observed between Sepsis group and SIRS group patients (Table 2), as well as between patients with severe sepsis or septic shock (data not shown).