Regulation of interleukin‐1 receptors on AtT‐20 mouse pituitary tumour cells

To study the cellular mechanisms of interleukin‐I (IL‐1) in the pituitary corticotroph, we studied the properties of IL‐1 receptors on a mouse pituitary ACTH‐producing cell line, AtT‐20. Scatchard plot analysis revealed a single type of receptor with a Kd(dissociation constant) of 93 pM, and 482 binding sites/cell. [125I]IL‐1α binding competed with IL‐1α and IL‐1β in an equimolar fashion. A 24 h pre‐incubation with either CRH, epinephrine or nor‐epinephrine increased the [125I]IL‐1α binding sites in the AtT‐20 cells and conversely, a similar pre‐incubation with either dexamethasone or tumour necrosis factor‐α (TNFα) decreased them without affecting the affinity of the receptors in either case.