Catabolism of avian and mammalian haptoglobins and their complexes with haemoglobin in chicken. 
The following 125I-labelled preparations of human and chicken haptoglobins (Hph, Hpc) and their complexes with human and chicken haemoglobins (Hph-Hbh, Hpc-Hbc, Hph-Hbc) were injected intravenously to chickens.  Hpc exhibited long half-life time (t1/2 = 12.9 hr), whereas the homologous Hpc-Hbc complex disappeared from circulation faster (t1/2 = 3.1 hr).  This suggested that the Hpc-Hbc complex was internalized by the receptor-mediated process in the avian liver.  Mammalian Hph-Hbh complex was eliminated from chicken circulation rather fast (t1/2 = 0.5 hr) in contrast to "mixed" Hph-Hbc complex which was characterized by the relatively long half-life time (t1/2 = 4.4 hr).  Hph-Hbc complex displayed 1-2 sites for binding an anti-Hph antibody i.e. less than Hph-Hbh or Hph-Hbc complexes.  The Hph binding with Hbc seems to be weaker than with mammalian haemoglobins.