Characterization of ICAM-4 binding to the I domains of the CD11a/CD18 and CD11b/CD18 leukocyte integrins. Serum cytokine analysis revealed IL-8 levels of 146 pg/ml (0-70) and IL-1 levels of 5.5 pg/ml (0-0.6). Neutrophil-activating protein 1/interleukin 8 stimulates the binding activity of the leukocyte adhesion receptor CD11b/CD18 on human neutrophils.