Identification and characterization of specific receptor for interleukin-8 from the surface of human monocytes

A specific receptor for interleukin-8 has been identified on the surface of human monocytes using I-125 IL-8 as a probe. A binding kinetic pattern shows that saturation was attained after 90 min and that the receptor was distinct from the receptors of other cytokines (IL-1 alpha, IL-2, TNF alpha, GMCSF) and FMLP. Scatchard analysis of the binding data shows that 7000-10,000 receptors/monocyte are present with an equilibrium Kd 7x10(-9)M. By immunoblot, the receptor for IL-8 showed a sharp band with approximate M.W. 59kD, consistent with the M.W. of IL-8 receptor of neutrophils. In Boyden Chamber, monocytes migrated towards IL-8 and the cytokine was observed to induce transient rise of intracellular Ca++ in the cells. Thus, identification of functionally active IL-8 receptor in monocyte may be helpful for understanding its possible role during inflammation.