No abstract

The salient features of systemic or local inflammation are the myriad of cellular and humoral interactions that result in elicitation of inflammatory leukocytes. In this study using specialized connective tissue, intact whole blood, we demonstrate the gene expression of two novel chemotactic factors. The buffy-coat cellular expression of neutrophil chemotactic/activating factor/interleukin 8 (IL-8) and monocyte chemotactic/activating protein (MCP-1) mRNA were time and dose-dependent in response to either lipopolysaccharide or zymosan stimulation. This system with the complexity of tissue provides a unique model for the determination of chemotactic cytokine gene expression.

Interleukin-8 (IL-8) is a potent neutrophil chemoattractant, produced by a variety of immune and nonimmune cells in response to exogenous and host-derived inflammatory stimuli. We demonstrate here that a suspension of normal bone marrow mononuclear cells, consisting principally of myeloid precursors, produces IL-8 in response to stimulation with lipopolysaccharide (LPS). IL-8-specific mRNA is rapidly induced, being detected first 30 min after stimulation. IL-8 is detected by enzyme-linked immunosorbent assay within 2 h of stimulation, with steady a increase in its level through 72 h. Further studies demonstrated that LPS could serve as a primary stimulus for the expression of IL-8, since LPS challenge in the presence of cycloheximide resulted in superinduction of bone marrow mononuclear cell-derived IL-8 mRNA. These investigations suggest that the stimulatory effect of LPS is independent of other cytokines such as IL-10. When compared with LPS, I-1,1 proved to be a weak signal for the expression of IL-8 by bone marrow mononuclear cells. In a dose-response study, the maximum stimulatory concentration of IL-11 (300 pg/ml) resulted in the production of 500 pg of IL-8 per 106 cells, whereas 1 ,ug of LPS resulted in the production of 5.5 ng/106 cells. Although IL-11 was not a particularly potent stimulus for IL-8 production by bone marrow mononuclear cells, peripheral blood mononuclear cells were highly susceptible to IL-1p challenge. In addition, the potential dependence of LPS-induced marrow-derived IL-8 production on the intermediate synthesis of IL11 was further investigated. Results of studies assessing kinetics, addition of cycloheximide, and blocking with IL-113 neutralizing antibody were all consistent with the ability of LPS to directly induce bone marrow-derived IL-8 independently of IL-11.These investigations demonstrate that bone marrow may be a significant source of IL-8 and may play a significant role in acute infectious, inflammatory responses.