Antibodies to factor VIII. I. Variations in stability of antigen-antibody complexes in hemophilia A.

Human factor VIll-anti-factor VIII comThe extent of dissociation was measured plexes were formed in vitro in slight antiby the recovery of anti-factor VIII activity. gen excess, using plasma of hemophiliacs Increasing resistance of complexes towho were found to have antibodies neuwards dissociation was observed in the tralizing AHF activity. These complexes, plasma of the patients whose titer of instable at +37uC and pH 7.4, were subhibitor was increasing after recent transmitted to classical procedures known to fusions. These observations suggested the favor dissociation of antibody from antigen. emergence, as a direct consequence of reThe methods used to obtain dissociation, newed antigenic stimulation, of a populaincubations at +56cC and at pH 4.2, intion of different antibodies characterized activated both unbound factor VIII and that by higher combining strength. released as a consequence of dissociation.