Objective: Identification of the association of killer cell immunoglobulin-like receptor (KIR) genes with SLE and accompanying infections.
Methods: Presence or absence of all 14 KIR genes was studied for association with SLE by case-control studies. A total of 417 SLE cases, 72 RA cases and 256 controls, all of Japanese descent, were enrolled.
Results: The carrier frequency of KIR2DL5 was significantly decreased in SLE patients compared with healthy controls [39.3 vs 50.4%; odds ratio (OR) = 0.64; 95% CI 0.36, 0.92; P = 0.005). When the prevalence of severe infections was analysed in 184 SLE patients, whose medical records were available, KIR2DL5 carriers were at an increased risk of overall infection and viral infection (crude OR = 2.66; 95% CI 1.43, 4.92; P = 0.017 and crude OR = 2.31; 95% CI 1.15, 4.62; P = 0.017, respectively). After adjusting for methylprednisolone pulse and/or cyclophosphamide pulse therapy, KIR2DL5 carriers were at significantly greater risk of infectious events overall (adjusted OR = 2.45; 95% CI 1.24, 4.81; P = 0.0095). However, KIR2DL5 carriers were marginally associated with an increased risk of viral infectious events (adjusted OR = 2.03; 95% CI 0.94, 4.41; P = 0.0718).
Conclusion: KIR2DL5 was significantly associated with a decreased risk of SLE as well as an increased risk of infectious events overall in SLE patients. Our data suggest a further role of KIRs in the pathogenesis of autoimmune diseases and infection.