Binding of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to cytosolic Ah receptor (AhR) in human tonsils

The AhR was identified and characterized in cytosol from human tonsils obtained at surgery from children 2–6 years of age. The receptor was detectable with [3H]TCDD in tonsils from all donors studied, and sedimented at ≈ 9 S on sucrose gradients in low ionic strength. Scatchard plot analysis revealed that, similar to AhR from other human tissues, the apparent binding affinity of the AhR in human tonsils (≈ 8 nM) was in all cases lower than that observed in rat liver cytosol (1–2 nM).