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It is now recognized that epithelial cells lining airways and alveoli are capable of releasing various mediators, which have the potential to modulate local inflammatory reactions. The amount of the 16 kDa Clara cell protein (CC16), an inhibitor of phospholipase A2 activity produced by pulmonary epithelial cells, was measured by means of a sensitive immunoassay in the unconcentrated bronchoalveolar lavage fluid (BALF) of 13 control subjects, and in patients with acute lung injury (14 with the full-blown adult respiratory distress syndrome (ARDS); 21 after standard cardiopulmonary bypass surgery, a known risk factor for ARDS). The level of CC16 was compared with other markers of inflammation with a wide range of molecular weights: albumin (nephelometry); total protein (spectrophotometry); beta 2-microglobulin (latex immunoassay); cystatin C (latex immunoassay); alpha 1-antitrypsin (immunoradiometry), and lipocortin-1 (enzyme-linked immunosorbent assay (ELISA)). The Clara cell protein (CC16) was detectable in all BALF, and significantly higher levels of this protein were observed in BALF from patients with acute lung injury. Changes in BALF Clara cell protein levels differed from those of alpha 2-macroglobulin and the natural phospholipase inhibitor lipocortin-1. Alpha 2-macroglobulin levels were not significantly enhanced in patients at risk for ARDS, but were increased in patients with ARDS; whereas, lipocortin 1 levels were not elevated in either group. Pretreatment of patients at risk for ARDS with high dose methylprednisolone did not alter the amount of Clara cell protein recovered in BALF. The mean CC16 level in BALF from patients with ARDS who died was significantly lower than from those who survived. The data presented in this study suggest that pulmonary epithelial cells secrete a natural anti-inflammatory protein during acute lung injury, which might have a protective and immunosuppressive role.

The neutrophil enzyme elastase is a potent secretagogue of airway secretory cells, and elastase is present in high concentrations in sputum of patients with hypersecretion (e.g., cystic fibrosis, bronchiectasis). Interleukin-8 (IL-8), a recently discovered cytokine with potent neutrophil chemotactic properties in vitro, is also found in the sputum of these patients. We used an isolated tracheal segment in dogs in vivo to study the effect of IL-8 in causing neutrophil accumulation, elastase release, and secretion (by measuring lysozyme concentrations) in the luminal superfusate. IL-8 caused a potent time-dependent neutrophil accumulation at between 3 and 6 h. The effect was significant at 10(-9) and maximum at 10(-8) M. No increase in free elastase, cathepsin G, or lysozyme was detected in the superfusate. Thus, in contrast to previous studies showing that ragweed antigen causes the accumulation of neutrophil elastase which in turn causes lysozyme secretion, IL-8 causes neutrophil accumulation without granule secretion (or subsequent secretagogue activity). The findings were confirmed with dog and human neutrophils in vitro.

Besides its effects on tumour cells, tumour necrosis factor (TNF) also acts on a variety of other cells, thus enhancing inflammatory and immune processes. In view of the prominent role of the mast cell in such processes, the aim of the present study was to assess the effects of recombinant TNF-alpha on human mast cells. Mast cells from the infant foreskin obtained during circumcision were dispersed by an enzymatic technique using collagenase and hyaluronidase. Cells thus obtained were pooled, washed and separated by Percoll gradient centrifugation. Mast cells, with a purity of 70-90% were incubated for 60 min with 10(-11) to 10(-7) M rTNF-alpha. Histamine and tryptase levels were assessed in the cell supernatant by spectrofluorometry and radioimmunoassay (RIA) respectively. A concentration dependent release of histamine was observed, which reached a maximum of 11.5 +/- 2.2 nmol/10(6) cells at 10(-8) M rTNF. Release of tryptase was also concentration dependent and reached a maximum of 293 +/- 105 mU/10(6) cells (10(-8) rTNF). rTNF-alpha thus appears to be a direct stimulus for mast cells to degranulate and to release both histamine and tryptase.

The presence of histamine and tryptase in serum during and after coronary artery bypass grafting may be an indication for the induction of inflammation. One group of patients received no glucocorticoids, a second one received methylprednisolone before extracorporeal circulation. In the steroid group, no effects were seen on the basal levels of histamine and tryptase. In the other group, two peak levels of histamine were observed, one peak 10 minutes after starting extracorporeal circulation and another peak 4 hours post-surgery. In this group, tryptase was only elevated during the period of extracorporeal circulation. There were no differences between both groups in complement activation. It was concluded that during surgery mast cells were activated but, since tryptase levels decreased in the post-operative period, the increase in histamine level can only be explained by activation of basophils.

The acute respiratory distress syndrome (ARDS), a process of non-hydrostatic pulmonary edema and hypoxemia with a variety of etiologies, consists of diffuse, acute parenchymal lung injury that results in increased permeability and mechanical dysfunction [1]. In recent years, a large body of research has focused on a key role for polymorphonuclear leukocytes (PMN) in the pathogenesis of ARDS. Recently, interest has shifted from formed blood elements to both the alveolar macrophage, the resident phagocyte of the alveolar space, and cytokines. In this hypothesis, ARDS is related to the uncontrolled production and liberation of many substances, including cytokines. Cytokines are low-molecular weight proteins, arbitrarily divided into several classes: interleukins (originally described as messengers between leukocytes), interferons (named after their ability to interfere in the life cycle of viruses), growth factors, colony-stimulating factors and chemokines. However, most cytokines are pleiotropic and have multiple, diverse, biological activities [2], frequently not related to their original name.

Study of leukocyte activation and release of toxic mediators during extracorporeal circulation (ECC). ECC can be used to study the potential protective effect of a pharmacon against neutrophil-mediated lung injury. Clinical studies have indicated that N-acetylcysteine (NAC) may improve systemic oxygenation and reduce the need for ventilatory support when given to patients with acute lung injury.Cardiac surgery patients were pretreated with high-dose NAC in order to assess the potential role of NAC to interfere with neutrophil-mediated inflammation and lung injury.18 patients who underwent ECC: group 1 (n = 8) no premedication (only placebo); group 2 (n = 10) NAC (72 mg/kg i.v. as a bolus, later 72 mg/kg over 12 h).In group 2, the partial pressure of oxygen in arterial blood/fractional inspired oxygen 4 h after surgery was significantly higher than in group 1 (213 +/- 31 vs 123 +/- 22; p = 0.044). NAC pretreatment prevented an increase in plasma neutrophil elastase activity (18.9 +/- 6.9 vs 49.9 +/- 5.6 ng/ml in group 1 at the end of ECC; p = 0.027). Release of myeloperoxidase (MPO) was not affected (group 1:1105 +/- 225 ng/ml vs group 2:1127 +/- 81 at the end of ECC; p = 0.63). At the end of ECC, total antigenic human neutrophil elastase (group 1:671 +/- 72 ng/ml vs group 2:579 +/- 134; p = 0.37) and complex formation between elastase and alpha 1-proteinase inhibitor were no different in the two groups. There were no significant difference in cellular composition and mediators in the lavage fluid, although values for total number of neutrophils, elastase, MPO and interleukin-8 were lower in group 2.Pretreatment with NAC may prevent lung injury by diminishing elastase activity. Since the release of mediators, especially MPO, is not affected, this diminished activity of elastase may be achieved by enhanced inactivation by antiproteases after initial treatment.

1. The presence of histamine and tryptase in serum during and after coronary artery bypass grafting may be an indication of the induction of inflammation. 2. One group of patients received no glucocorticoids and a second group received methylprednisolone before extracorporeal circulation. In the steroid group no effects were seen on the basal levels of histamine (2.84 + 0.12 ng/ml) and tryptase (030 + 0.05 ng/ml) during and after surgery. In the other group two peak levels of histamine were observed: one at 10 min after starting extracorporeal circulation (4.19 +1.79 ng/ml) and another at 4h after surgery (8.26 +4.85 ng/ml). In this group tryptase was only elevated during the period of extracorporeal circulation (1.54+ 0.16 ng/ml). 3. There were no differences between the two groups in complement activation. C3a levels rose to 170 +8% and 180 +10% of the initial value in the steroid and non-steroid group, respectively. 4. It was concluded that during surgery mast cells were activated, but since tryptase levels decreased in the post-operative period, the second increase in the histamine level can be explained by activation of basophils or by an unknown mechanism for the release of histamine but not tryptase by mast cells. 5. In the bronchoalveolar lavage fluid the levels of histamine and tryptase showed no differences between the two groups of patients, but histamine was enhanced compared with normal levels.

An L-arginine-dependent pathway, by which L-arginine is metabolised to citrulline and nitrogen oxides, has been recently identified in some cell types. In cultured rat lung fibroblasts the presence of L-arginine was necessary for the production of nitrite to be induced by rat recombinant interferon-gamma and synergistically enhanced by lipopolysaccharide and interleukin-1beta. Lipopolysaccharide and interleukin-1beta did not induce nitrite biosynthesis by themselves. Biosynthesis was apparently dependent on tetrahydrobiopterin, since it could be blocked by diaminohydroxypyrimidine, an inhibitor of tetrahydrobiopterin synthesis. Dexamethasone blocked nitrite production by a receptor-mediated mechanism. These data indicate that rat lung fibroblasts express an L-arginine-dependent nitric oxide synthase which can be induced by some mediators of inflammation.

Mast cells from infant foreskin obtained during circumcision were dispersed by an enzymatic technique, pooled, washed and purified. Mast cells, with a purity of 70–90% were incubated with 10−11 to 10−7M rTNFα. Histamine and tryptase levels were assessed in the cell supernatant and a concentration dependent release of histamine was observed. Histamine reached a maximum of 11.5±2.2 nmol/106 cells at 10−8M rTNF. Tryptase reached a maximum of 293±105 mU/106 cells (10−8M rTNF). rTNFα thus appears to be a direct stimulus for mast cells to degranulate and to release both histamine and tryptase.

An elevation in the serum creatine kinase (CPK) level (without a simultaneous rise in the MB fraction or massive ischaemic cerebral infarction) correlates with the extent of muscular damage. Although usually asymptomatic, it could evolve into a life-threatening condition of rhabdomyolysis complicated by acute renal failure and/or disseminated intravascular coagulation. Critically ill patients may present with an elevated CPK for a number of different reasons. We performed an observational prospective pilot study during 31 days in a mixed ICU in a tertiary referral teaching hospital in order to study the incidence of elevated CPK levels and its possible influence on outcome.