Associations of Killer Cell Immunoglobulin-like Receptor Genes with Complications of Rheumatoid Arthritis

We investigated whether killer cell immunoglobulin-like receptor (KIR) genes are risk factor(s) for rheumatoid arthritis (RA) and its clinical manifestations. One hundred and seventy-seven RA patients and 243 healthy individuals were tested for the presence of 11 KIR genes using PCR-SSP method. The frequencies of KIRs in patients with RA were similar to the frequencies in controls. However, RA patients positive for KIR2DL3 and negative for KIR2DS3 had earlier disease diagnosis. Additionally, KIR2DL2 and KIR2DS2 were significantly more frequent among RA patients with extra-articular manifestations and in its subgroup with vasculitis than in controls and in patients without these complications. Furthermore, the frequencies of KIR2DS1 and KIR3DS1 were lower in patients without bone erosions compared with healthy individuals. Relationships between the presence or absence of autoantibodies (rheumatoid factor and anti-cyclic citrullinated peptide) and KIR frequencies were also evaluated, but no significant differences were observed. These results suggest that particular clinical manifestations of RA may have different genetic backgrounds with respect to KIR genotype.