Detection of specific binding of [1,6-³H]2,3,7,8-tetrachlorodibenzo-p-dioxin ([³H]TCDD) in human leukocytes using electrofocusing in polyacrylamide gel

The binding of [1,6-³H]2,3,7,8-tetrachlorodibenzo-p-dioxin ([³H]TCDD) in human leukocyte cytosol has been studied using electrofocusing in polyacrylamide gel. One single peak of bound [³H]TCDD is found after completed focusing with an isoelectric point of 6.0. The binding capacity for 1.5 nM [³H]TCDD in the leukocyte cytosol was completely saturated by incubation in the presence of 150 nM unlabelled 2,3,7,8-tetrachlorodibenzofuran. [³H]TCDD also binds to a single binding species in human serum and plasma which focuses at pH 5.2 and which is not saturated by the addition of a 100-fold excess of unlabelled 2,3,7,8-tetrachlorodibenzofuran to the incubation. The levels of specific binding of [³H]TCDD in leukocytes from healthy blood donors ranged from 0 to 50 fmol/mg cytosolic protein.