Intradermal catabolism of rabbit IgG and its fragments

Disappearance of rabbit EgG and its Fc fragment from the injected sites in skin and also the relationship to reverse passive cutaneous anaphylaxis (RPCA) were studied using guinea pigs. Rabbit IgG and its Fc fragment, trace labelled with -125-I, disappeared from the injected sites with half-lives of 12--14 and 6--7 hr, respectively. The shorter half-life of the Fc fragment explained why its activity to provoke RPCA disappeared more rapidly than that of intact IgG as the sensitization period was prolonged. The ability to provoke RPCA did not seem to influence the persistence of Fc fragment in the sites, since F(ab')2 as well as Fab fragments had the same half-life as Fc fragment.