Complement sensitivity of PIGA(−) RBCs. (A) Sensitivity toward complement mediated lysis. Lysis of RBCs from mosaic mice (▵PIGA) and from normal control mice were exposed to different dilutions of acidified absorbed rat serum (S) or acidified absorbed rat serum after heat inactivation (HS; see Materials and Methods) for 60 minutes at 37^oC. The supernatant shows the degree of hemolysis. (B, D) Lysis of RBCs from mosaic mice (filled symbols) and from normal control mice (empty symbols) at different serum dilutions from rat and (B) human (D). (C, E) Preferential lysis of PIGA(−) RBCs by rat and (C) human serum (E) at serum dilutions that lyse only blood cells from mosaic mice but not from normal control mice (full lines). Dotted lines show the percentage of PIGA(−) RBCs exposed to heat inactivated serum. Serum dilutions shown in C: triangle 1:2, rectangle: 1:4, squares: 1:8; in E: rectangle: 1:4, squares: 1:8, circles: 1:16, and triangles: 1:32.