KLRD1 and systemic lupus erythematosus: In agreement with the previous data reporting an aberrant NK cell education process due to the presence of functional anti-CD94/NKG2A and anti-CD94/NKG2C antibodies in 3.4% of patients with SLE (69, 70), the frequency of autoantibodies to eight different inhibitory receptors involved in the modulation of NK cytotoxicity was investigated (57).