Binding of anti-factor VIII antibodies over time. Immunoprecipitation analysis of antibodies binding to the A2 domain of factor VIII, with plasma samples of patient A from various time points. Lanes 1 through 4, plasma of patient A from 1992, 1993, 1994, and 1995; and lanes 5 and 6, plasma of patient B from 1993 and 1995. Some nonspecific binding of a protein of approximately 100 kD was observed in this particular experiment. A molecular weight marker is given on the right of the figure.