Aluminum-binding serum proteins: desferrioxamine alters serum aluminum speciation

The aluminum content of four size classes of protein (high and low molecular weight, transferrin/albumin and a fraction provisionally termed albindin) in sera from healthy volunteers (group I) and from aluminum workers with normal (group II) and high (group III) total serum aluminum was compared using size exclusion chromatography and electrothermal atomic absorption spectroscopy. In the absence of any drug treatment the transferrin/albumin fraction was the major carrier, containing 29% to 33% of the aluminum recovered, in all three subject groups. Desferrioxamine treatment of groups II and III significantly decreased the proportion of aluminum bound by albumin/transferrin (P less than 0.05 in group III) and increased that bound by albindin (P less than 0.05 in groups II and III). The albindin fraction contained over 40% of the aluminum recovered from sera of group III subjects during desferrioxamine treatment. We conclude that the albindin fraction contains a protein or proteins that can form stable complexes with aluminum which may be important in preventing aluminum toxicity.