HIGH-AFFINITY INTERLEUKIN-6 BINDING-SITES IN BOVINE HYPOTHALAMUS

The cytokine interleukin-6 (IL-6) has been proposed to interact with the hypothalamic-pituitary axis. The present data provide the first reported evidence of high affinity binding sites for [I-125]IL-6 in brain tissue, specifically bovine hypothalamic membranes. Binding was saturable and represented a single site, with a K(d) of 316 +/- 49 pM and receptor density of 15.8 +/- 3.2 fmol/mg protein. Other cytokines tested did not interact with this site, but a neutralizing monoclonal anti-IL-6 antibody blocked specific binding. These findings support the proposed involvement of IL-6 in communication between neural and immune systems.