ENHANCED RELEASE OF ELASTASE IS NOT CONCOMITANT WITH INCREASED SECRETION OF GRANULOCYTE-ACTIVATING CYTOKINES IN WHOLE-BLOOD FROM PATIENTS WITH SEPSIS

Background: The proteolytic enzyme elastase released by granulocytes ( polymorphonuclear leukocytes [PMN]) in high concentrations during seps is causes degradation of essential plasma proteins, endothelial damage , and tissue edema. This may result in organ dysfunction and organ fai lure during sepsis, since increased elastase plasma levels correlate w ith the mortality rate of patients with sepsis. In vitro studies demon strated a regulatory role of inflammatory cytokines (tumor necrosis fa ctor-alpha [TNF-alpha], interleukin 1 beta [IL-1 beta], IL-8]) upregul ating protease release by PMN. In this light, the interactions between cytokine release by macrophages and altered elastase secretion during sepsis remain to be determined. Methods: An ex vivo model consisting of lipopolysaccharide stimulation of human whole blood as a relevant p hysiological milieu was used. Heparinized blood was obtained from 20 p atients with sepsis syndrome (APACHE II [Acute Physiology and Chronic Health Evaluation II] score 28.5 +/- 1.2 points [mean +/- SD]) on days 0 through 3, 5, 7, and 10 after sepsis diagnosis and from 20 control patients without infection. Blood was incubated with lipopolysaccharid e (1 mg/L) for 8 hours. Plasma levels of elastase, TNF-alpha, IL-1 bet a, and IL-8 were determined using enzyme-linked immunosorbent assay or bioassay (TNF-alpha), respectively. Results: Elastase plasma levels i n whole blood from patients with sepsis were increased up to 188% (P<. 01) above normal, while the release of TNF-alpha (-87%), IL-1 beta (-9 1%), and IL-8 (-51%) was markedly (P<.01) decreased compared with cont rol patients. Neutralization of TNF-alpha or IL-1 beta did not attenua te the increased release of elastase. Conclusions: These data indicate an increased release of elastase by PMN despite a reduced secretion o f PMN-activating cytokines. Although priming effects of TNF-alpha, IL- 1 beta, and IL-8 on protease secretion in vivo cannot be excluded comp letely, other mediators or mechanisms may be involved in the upregulat ion of detrimental protease release during sepsis.