KIR2DL1 and systemic lupus erythematosus: Initially we screened SLE, pSS, SSc, and HD sera (Table 1) for the presence of IgG that bound to KIR2DL1, 2DL2, 2DL3, 3DL1, 3DL2, 2DS2, 2DS4, or 2DL4-expressing HEK293T transfectants.