REGULATION OF INTERLEUKIN-1 RECEPTORS ON ATT-20 MOUSE PITUITARY-TUMOR CELLS

To study the cellular mechanisms of interleukin-1 (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 K(d) (dissociation constant) of 93 pM, and 482 binding sites/cell. [I-125]IL-1-alpha binding competed with IL-1-alpha and IL-1-beta in an equimolar fashion. A 24 h pre-incubation with either CRH, epinephrine or nor-epinephrine increased the [I-125]IL-1-alpha binding sites in the AtT-20 cells and conversely, a similar pre-incubation with either dexamethasone or tumour necrosis factor-alpha (TNF-alpha) decreased them without affecting the affinity of the receptors in either case.