Deficient ferritin immunoreactivity in visceral organs from four patients with Niemann-Pick disease type C

Ferritin, the major iron storage protein, was found to be undetectable on immunoblot analysis of spleen and liver extracts from four patients with Niemann-Pick disease type C (NPC). The patients had died from different clinical forms of this storage disease of still unknown etiology. The absence of ferritin immunoreactivity was shown using two different antisera, raised in rabbits, against ferritin from human spleen containing predominantly light-chain subunits (L-ferritin). Further evidence of absent L-ferritin in visceral tissues was provided by immunohistochemical studies performed in one of the four NPC patients. However, heavy-chain and light-chain ferritin mRNAs could be identified in cultured fibroblasts from this patient. The finding of deficient ferritin immunoreactivity is suggestive of an additional biochemical abnormality that is as marked as the known impairment of the transport of exogenously derived cholesterol in this complex lysosomal storage disorder.