LY9 and systemic lupus erythematosus: Previous limited reports suggested an altered expression of isolated SLAMF protein on the surface of T and/or B cells from SLE patients compared to healthy controls (SLAMF1[15], SLAMF3 [16], SLAMF4 [17, 18], SLAMF6 [19, 20] and SLAMF7 [18]).