Characterization of antibodies present in plasma of a patient with inhibitors to factor VIII.

Binding of antibodies to metabolically labeled factor VIII fragments corresponding to the factor VIII light chain and the C2 domain was evaluated by immunoprecipitation. The samples were analyzed under reducing conditions on a 12.5% (wt/vol) sodium dodecyl sulfate–polyacrylamide gel. (lanes 1 and 2) Positive control (CLB-CAg 117); (lanes 3 and 4) negative control (normal plasma); (lanes 5 and 6) patient's plasma. Arrowheads indicate C2 domain (C2) and factor VIII light chain (LCh). Molecular weight markers in kd are indicated at the right.