The reaction of 16alpha-hydroxyestrone with erythrocytes in vitro and in vivo

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Abstract
16α-Hydroxyestrone (16αOHE) had been shown previously to react with albumin, forming stable covalent adducts with lysine residues. The incubation of [3H]16αOHE with whole blood also results in the incorporation of tritium into cells, with the rate of incorporation paralleling that of 16αOHE-protein adduct formation. 32% of erythrocyte acid-precipitable radioactivity was found to be present within membrane proteins and electrophoresis demosnstrated that several of these proteins are modified by [3H]16αOHE. Membrane proteins from the red cells of ten individuals were reduced with sodium borohyride, acid hydrolyzed, and the 16αOHE-lysine adducts purified by hydrophobic chromatography and reverse-phase high-pressure liquid chromatography. The amount of these adducts was quantitated by radioimmunoassy and found to be five times higher than the plasma levels of free 16αOHE. This reflects most likely the accumulation of 16αOHE-proteins may contribute to our understanding of systemic lupus erythematosus, an autoimmune disease in which elevated levels of 16αOHE occur.