Decreased spontaneous and lipopolysaccharide stimulated production of interleukin 8 by polymorphonuclear neutrophils of patients with active systemic lupus erythematosus

Objective. Interleukin 8 (IL-8) acts as a potent chemotactic cytokine and also as an autocrine factor for polymorphonuclear neutrophils (PMN), thus amplifying the acute inflammatory reaction. We undertook to study the IL-8 producing capacity of PMN in patients with systemic lupus erythematosus (SLE). Methods. PMN from twelve patients with active SLE, from fifteen patients with inactive disease and from sixteen healthy individuals were incubated for 24 hours in medium alone, or in medium with lipopolysaccharide (LPS) or TNF-α. The IL-8 concentration in the culture supernatants was measured by an enzyme linked immunosorbent assay. Results. We found that the spontaneous and LPS-stimulated, but not TNF-α-stimulated, production of IL-8 by the PMN of active SLE patients were significantly lower than that of healthy individuals. The impaired IL-8 production by SLE-PMN was linked to disease activity but not to the administration of steroid, because incubation of normal PMN or inactive SLE-PMN with prednisolone (1 μg/ml and 5 μg/ml) for 24 hours did not affect IL-8 production. In addition, IL-8 production increased in three active SLE patients after effective treatment with immunosuppressants but not in two cases of ineffective treatment, in the follow-up study. Conclusion. These results suggest that decreased IL-8 production is one of the defects of PMN in patients with active SLE, which might predispose SLE patients to infection.