Characterization of the human interleukin 1 receptor on human polymorphonuclear leukocytes

Interleukin 1 (IL-1) is a mediator of inflammation with multiple proinflammatory and immunologic enhancing activities. Human polymorphonuclear leukocytes (PMN) also play a major role in the inflammatory response. We have found that PMN possess a single type of high affinity receptor for human recombinant (r) IL-1 alpha with an apparent dissociation constant of 0.28 nM. Approximately 700 receptors are present per cell. Binding is rapid with 50% of maximal binding occurring within 20 min at 4 degrees C. Internalization of the receptor occurs within 25 min after shifting the cells to 37 degrees C. The receptor exhibits an apparent molecular weight of approximately 60-70 kDa. Electron microscopic autoradiography studies reveal that the 125I-rIL-1 alpha localized in the nucleus within 180 min after shifting cells to 37 degrees C. The accumulation of relatively high levels of 125I-rIL-1 alpha in the nucleus is consistent with earlier observations on the nuclear localization of IL-1 in T lymphocytes. The possibility that IL-1 may exert a direct action in the nucleus remains to be determined.