NF-kappa B is a pleiotropic regulator of a variety of genes implicated in the cellular response to injury. This function has been attributed to the coordinated binding of subunits of NF-kappa B to distinct regions of the promoter elements of numerous genes, including cytokines, growth factor receptors, and adhesion molecules. Antisense phosphorothioate oligonucleotides to the p50 and p65 subunits of the NF-kappa B complex were used to define the physiologic role of this transcription factor in resting and stimulated granulocytes. A reduction in the expression of p65 was produced by treatment with the phosphorothioate antisense oligodeoxynucleotide. This reduction was accompanied by rapid changes in the cellular adhesion of dimethyl sulfoxide-differentiated HL-60 leukemia cells stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA). These effects were characterized by a marked reduction in CD11b integrin expression on the surface of treated cells. Furthermore, the p65 antisense oligomer effectively abolished an upregulation of CD11b that was produced by formyl-met-leu-phe and TPA. However, the p65 antisense phosphorothioate oligodeoxynucleotide had no significant effect on the production of reactive oxygen intermediates or on phagocytosis by these cells. These findings indicate that antisense oligomers to p65 can be used to define the role of NF-kappa B in the activation pathways of neutrophils.