Characterization of the Interaction Between Recombinant Human lnterferon‐γ and Its Receptor on Human Polymorphonuclear Leukocytes

The interaction of human recombinant interferon‐γ (rlFN‐γ) with human polymorphonuclear cells (PMN) was investigated. Bolton‐Hunter radioiodinated rlFN‐γ bound to PMN in a specific and saturable manner. Eleven hundred binding sites were observed with a K a of 0.56 x 10 10 M ‐1 . Binding to PMN was rapid with a K 1 of 9 x 10 5 M ‐1 sec ‐1 at 4°C. At 37°C binding was complete within 6 min. About 50% of bound ligand was internalized within 30 min at 37°C. The receptor demonstrated moderate lability at 37°C in culture. After 1 h at 37°C, PMN lost 80% of their 125 l‐rlFN‐γ binding sites. This loss was reversed in part by the presence of interleukin‐1 in the culture, but not tumor necrosis factor. These studies provide a framework for further investigation into the signalling process of rlFN‐γ on PMN.