Evidence for the localization of haemopexin immunoreactivity in neurones in the human brain.

Haemopexin is a 60 kDa serum glycoprotein responsible for the transport of haem to tissues such as liver, by receptor-mediated endocytosis, in an analogous manner to the iron transport protein transferrin, with recycling of intact haemopexin. The immunocytochemical distribution of haemopexin has been investigated, using a monospecific polyclonal antiserum to human haemopexin, in human brain. Neurones in all the brain regions studied showed immunostaining of the soma, axons and dendrites. A few scattered glial cells exhibited positive immunostaining. Oligodendrocytes and choroid plexus epithelial cells lacked haemopexin immunoreactivity. Thus, haemopexin is present within neurones and we propose that this protein may play an important role in haem transport for neuronal iron homeostasis.