KIR3DL1 and systemic lupus erythematosus: In an attempt to confirm the presence of anti-KIR autoantibodies and to address their specificity in more detail, sera from the 10 SLE patients reacting with >3 KIRs, the three anti-KIR-positive HD, and eight anti-KIR-negative HD were analyzed for their ability to interfere with the binding of monoclonal anti-KIR antibodies to primary NK cells from a HD.