LAIR1 and mixed connective tissue disease: First, we analyzed the expression of LAIR1 receptor on peripheral B cells of SLE (n = 50, table 1), AR (n = 14), SSc (n = 20), or MCTD (n = 24) patients and HD (n = 40), by staining PBMC with anti-LAIR1, anti-CD20 mAb followed by PE or Alexafluor647-conjugated anti-isotype specific GAM and sIgM-FITC conjugated antibodies.