Leukocyte L-selectin is up-regulated after mechanical trauma in adults

Prospective flow cytometry analysis of leucocyte subsets in critically ill patients who develop sepsis: a pilot study

PURPOSE

Sepsis in critically ill patients with injury bears a high morbidity and mortality. Extensive phenotypic monitoring of leucocyte subsets in critically ill patients at ICU admission and during sepsis development is still scarce. The main objective of this study was to identify early changes in leukocyte phenotype which would correlate with later development of sepsis.

METHODS

Patients who were admitted in a tertiary ICU for organ support after severe injury (elective cardiac surgery, trauma, necessity of prolonged ventilation or stroke) were sampled on admission (T1) and 48-72 h later (T2) for phenotyping of leukocyte subsets by flow cytometry and cytokines measurements. Those who developed secondary sepsis or septic shock were sampled again on the day of sepsis diagnosis (Tx).

RESULTS

Ninety-nine patients were included in the final analysis. Nineteen (19.2%) patients developed secondary sepsis or septic shock. They presented significantly higher absolute monocyte counts and CRP at T1 compared to non-septic patients (1030/µl versus 550/µl, p = 0.013 and 5.1 mg/ml versus 2.5 mg/ml, p = 0.046, respectively). They also presented elevated levels of monocytes with low expression of L-selectin (CD62Lneg monocytes) (OR[95%CI] 4.5 (1.4-14.5), p = 0.01) and higher SOFA score (p < 0.0001) at T1 and low mHLA-DR at T2 (OR[95%CI] 0.003 (0.00-0.17), p = 0.049). Stepwise logistic regression analysis showed that both monocyte markers and high SOFA score (> 8) were independently associated with nosocomial sepsis occurrence. No other leucocyte count or surface marker nor any cytokine measurement correlated with sepsis occurrence.

CONCLUSION

Monocyte counts and change of phenotype are associated with secondary sepsis occurrence in critically ill patients with injury.

Moderate to severe leukocytosis with vasopressor use is associated with increased mortality in trauma patients

Background

Leukocytosis is a rise in white blood cell (WBC) count and clinical outcomes of moderate to severe leukocytosis in trauma patients have not been described. We hypothesized that trauma patients with severe leukocytosis (SL; ≥40.0 × 109 leukocytes/L) have higher rates of in-hospital complications and mortality than those with moderate leukocytosis (ML; 25.0-39 × 109 leukocytes/L).

Methods

We performed a retrospective analysis (2010-2017) on trauma patients developing ML or SL at a single Level-I trauma center. A multivariable logistic regression analysis for risk factors were performed.

Results

From 15,807 trauma admissions, 332 (2.1%) had ML or SL. Of these, 308 (92.8%) were ML and 24 (7.2%) were SL. Patients with ML and SL reached their peak WBC count in 1 and 10 days after admission respectively (p < 0.001). SL patients suffered higher rates of in-hospital complications (p < 0.05) and mortality compared to those without ML or SL (14.5% vs. 3.3%, p < 0.001). Between ML and SL, mortality rates rose with leukocytosis severity (13.3% vs. 29.2%, p = 0.03). Among all patients with ML or SL, vasopressor use was the strongest independent risk factor for mortality (OR 12.61, p < 0.001).

Conclusion

Clinicians should be weary of the increased mortality rates and in-hospital complications in SL patients. Among patients with ML or SL, vasopressor use, rather than SL, was the strongest predictor of mortality. Patients with ML had a quicker time course to peak leukocytosis compared to SL, suggesting these two entities to be distinct in etiology and outcome, warranting future research.

Biomarkers to Guide the Timing of Surgery: Neutrophil and Monocyte L-Selectin Predict Postoperative Sepsis in Orthopaedic Trauma Patients

Deciding whether to delay non-lifesaving orthopaedic trauma surgery to prevent multiple organ failure (MOF) or sepsis is frequently disputed and largely based on expert opinion. We hypothesise that neutrophils and monocytes differentially express activation markers prior to patients developing these complications. Peripheral blood from 20 healthy controls and 162 patients requiring major orthopaedic intervention was collected perioperatively. Neutrophil and monocyte L-selectin, CD64, CD11, CD18, and CXCR1 expression were measured using flow cytometry. The predictive ability for MOF and sepsis was assessed using the Receiver Operating Characteristic (ROC) comparing to C-reactive protein (CRP). Neutrophil and monocyte L-selectin were significantly higher in patients who developed sepsis. Neutrophil L-selectin (AUC 0.692 [95%CI 0.574–0.810]) and monocyte L-selectin (AUC 0.761 [95%CI 0.632–0.891]) were significant predictors of sepsis and were not significantly different to CRP (AUC 0.772 [95%CI 0.650–0.853]). Monocyte L-selectin was predictive of MOF preoperatively and postoperatively (preop AUC 0.790 [95%CI 0.622–0.958]). CD64 and CRP were predictive of MOF at one-day postop (AUC 0.808 [95%CI 0.643–0.974] and AUC 0.809 [95%CI 0.662–0.956], respectively). In the perioperative period, elevated neutrophil and monocyte L-selectin are predictors of postoperative sepsis. Larger validation studies should focus on these biomarkers for deciding the timing of long bone/pelvic fracture fixation.

The impact of intramedullary nailing on the characteristics of the pulmonary neutrophil pool in rodents

PURPOSE

Dysregulation of polymorphonuclear neutrophil (PMN) biology is associated with the development of inflammatory complications after trauma, such as acute respiratory distress syndrome (ARDS). It has been demonstrated that intramedullary nailing is both associated with altered pulmonary neutrophil deposition and the occurrence of ARDS. This standardized study aimed to characterize the long-term remote neutrophil response in the lungs in case of a femur fracture and intramedullary nailing.

METHODS

A standardized rat model including intramedullary nailing and a femur fracture was utilized. Groups were terminated after observation times of three, seven and 14 days. Neutrophils were isolated from lung parenchyma and broncho-alveolar lavage fluid (BALF) and analyzed by flow cytometry. Absolute neutrophil numbers as well as membrane expression levels of CD11b, CD62L, and CD11a were compared.

RESULTS

Pulmonary neutrophil numbers were increased 3 days after intervention. Membrane expression levels of CD11b (P < 0.01), CD62L (P < 0.01), and CD11a (P = 0.06) on parenchymal PMNs increased as well after 3 days. Thereafter, values restored gradually to physiological levels. Furthermore, neutrophil activation status patterns between parenchymal and BALF neutrophil pools did not correlate.

CONCLUSIONS

The current study demonstrates that IMN and a femur fracture are associated with transient increased pulmonary PMN deposition, as well as a specific pattern of activation characterized by temporary increased selectin and integrin receptor expression on pulmonary neutrophils. This phenomenon might play an important role in the pathomechanism of ARDS after IMN. Moreover, we found striking differences between parenchymal and BALF-neutrophil populations, demonstrating the limited readout potential of BALF analysis to investigate the entire pulmonary neutrophil pool.

Update on the role of endothelial cells in trauma

PURPOSE

This review gives an overview of physiological processes, mainly regarding vascular endothelial cells and their important role in hemostasis, information processing, and communication during trauma. An insight is given into molecules and cells involved in the first innate immune response through to the behavior of endothelial cells in developing trauma. The goal of this review is to show the overlap of crucial factors related to the endothelium and the development of trauma.

METHODS

A systemic literature search was performed using Google scholar and PubMed.

RESULTS

The results of the literature search showed that the endothelium, especially the vascular endothelium, is involved in various cellular and subcellular pathways of activation, suppression, and transfer of information. A variety of molecules and cells are orchestrated, subsequently the endothelium gets in contact with a traumatizing event.

CONCLUSION

The endothelium is one of the first barriers that comes into contact with exo- and endogenous trauma-related signals and is a pivotal point in activating subsequent pathways and cascades by transfer of information.

Effect of salvianolic acid B on TNF-α induced cerebral microcirculatory changes in a micro-invasive mouse model

PURPOSE

To investigate the effects of salvianolic acid B (SAB) on tumor necrosis factor a (TNF-α) induced alterations of cerebral microcirculation with a bone-abrading model.

METHODS

The influences of craniotomy model and bone-abrading model on cerebral microcirculation were compared. The bone-abrading method was used to detect the effects of intracerebroventricular application of 40 μg/kg·bw TNF-α on cerebral venular leakage of fluorescein isothiocyanate (FITC)- albulmin and the rolling and adhesion of leukocytes on venules with fluorescence tracer rhodamine 6G. The therapeutical effects of SAB on TNF-α induced microcirculatory alteration were observed, with continuous intravenous injection of 5 mg/kg·h SAB starting at 20 min before or 20 min after TNF-α administration, respectively. The expressions of CD11b/CD18 and CD62L in leukocytes were measured with flow cytometry. Immunohistochemical staining was also used to detect E-selectin and ICAM-1 expression in endothelial cells.

RESULTS

Compared with craniotomy method, the bone-abrading method preserved a higher erythrocyte velocity in cerebral venules and more opening capillaries. TNF-α intervention only caused responses of vascular hyperpermeability and leukocyte rolling on venular walls, without leukocyte adhesion and other hemodynamic changes. Pre- or post-SAB treatment attenuated those responses and suppressed the enhanced expressions of CD11b/CD18 and CD62L in leukocytes and E-selectin and ICAM-1 in endothelial cells induced by TNF-α.

CONCLUSIONS

The pre- and post-applications of SAB during TNF-α stimulation could suppress adhesive molecular expression and subsequently attenuate the increase of cerebral vascular permeability and leukocyte rolling.

ACTH- and cortisol-associated neutrophil modulation in coronary artery disease patients undergoing stent implantation

Background

Psychosocial stress and activation of neutrophil granulocytes are increasingly recognized as major risk factors of coronary artery disease (CAD), but the possible relationship of these two factors in CAD patients is largely unexplored. Activation of neutrophils was reported to be associated with stenting; however, the issue of neutrophil state in connection with percutaneous coronary intervention (PCI) is incompletely understood from the aspect of stress and its hypothalamic-pituitary-adrenal axis (HPA) background. Thus, we aimed to study cortisol- and ACTH-associated changes in granulocyte activation in patients undergoing PCI.

Methodology/Principal Findings

Blood samples of 21 stable angina pectoris (SAP) and 20 acute coronary syndrome (ACS) patients were collected directly before (pre-PCI), after (post-PCI) and on the following day of PCI (1d-PCI). Granulocyte surface L-selectin, CD15 and (neutrophil-specific) lactoferrin were analysed by flow cytometry. Plasma cortisol, ACTH, and lactoferrin, IL-6 were also assayed. In both groups, pre- and post-PCI ratios of lactoferrin-bearing neutrophils were relatively high, these percentages decreased substantially next day; similarly, 1d-PCI plasma lactoferrin was about half of the post-PCI value (all p≤0.0001). Post-PCI ACTH was reduced markedly next day, especially in ACS group (SAP: p<0.01, ACS: p≤0.0001). In ACS, elevated pre-PCI cortisol decreased considerably a day after stenting (p<0.01); in pre-PCI samples, cortisol correlated with plasma lactoferrin (r∼0.5, p<0.05). In 1d-PCI samples of both groups, ACTH showed negative associations with the ratio of lactoferrin-bearing neutrophils (SAP: r = −0.601, p<0.005; ACS: r = −0.541, p<0.05) and with plasma lactoferrin (SAP: r = −0.435, p<0.05; ACS: r = −0.609, p<0.005).

Conclusions/Significance

Pre- and post-PCI states were associated with increased percentage of activated/degranulated neutrophils indicated by elevated lactoferrin parameters, the 1d-PCI declines of which were associated with plasma ACTH in both groups. The correlation of plasma cortisol with plasma lactoferrin in the extremely stressed ACS before stenting, however, suggests an association of cortisol with neutrophil activation.

Oxidative burst of circulating neutrophils following traumatic brain injury in human

Besides secondary injury at the lesional site, Traumatic brain injury (TBI) can cause a systemic inflammatory response, which may cause damage to initially unaffected organs and potentially further exacerbate the original injury. Here we investigated plasma levels of important inflammatory mediators, oxidative activity of circulating leukocytes, particularly focusing on neutrophils, from TBI subjects and control subjects with general trauma from 6 hours to 2 weeks following injury, comparing with values from uninjured subjects. We observed increased plasma level of inflammatory cytokines/molecules TNF-α, IL-6 and CRP, dramatically increased circulating leukocyte counts and elevated expression of TNF-α and iNOS in circulating leukocytes from TBI patients, which suggests a systemic inflammatory response following TBI. Our data further showed increased free radical production in leukocyte homogenates and elevated expression of key oxidative enzymes iNOS, COX-2 and NADPH oxidase (gp91^phox) in circulating leukocytes, indicating an intense induction of oxidative burst following TBI, which is significantly greater than that in control subjects with general trauma. Furthermore, flow cytometry assay proved neutrophils as the largest population in circulation after TBI and showed significantly up-regulated oxidative activity and suppressed phagocytosis rate for circulating neutrophils following brain trauma. It suggests that the highly activated neutrophils might play an important role in the secondary damage, even outside the injured brain. Taken together, the potent systemic inflammatory response induced by TBI, especially the intensively increase oxidative activity of circulating leukocytes, mainly neutrophils, may lead to a systemic damage, dysfunction/damage of bystander tissues/organs and even further exacerbate secondary local damage. Controlling these pathophysiological processes may be a promising therapeutic strategy and will protect unaffected organs and the injured brain from the secondary damage.

Functional properties of granulocytes after thermal injury

Thermal injury, as well as other forms of severe trauma, induces simultaneous hyper- and anti-inflammatory response. While data about decreased number and responsiveness of T lymphocytes are largely consistent, reports concerning granulocytes following trauma are contradictory. Contrary to the evidence on the increased accumulation of granulocytes in the lungs or liver, the results from our laboratory demonstrated reduced granulocyte influx in the wound that heals in conditions of thermal injury. We also demonstrated evidence that indicates impaired signal transduction in granulocytes following thermal injury, as well as their divergent response regarding the adhesiveness, oxidative burst and nitric oxide production at the wound site.

Regulation of L-selectin expression by trauma-relevant cytokines

The leukocyte adhesion molecule L-selectin is important for the rolling of neutrophil granulocytes (PMN), the first step of the cascade leading to adhesion, diapedesis, and subsequent organ dysfunction. The activation of leukocytes in the posttraumatic course is assumed to be induced by different pro-inflammatory cytokines. In the present study, we investigated the effects of stimulation with pro- and anti-inflammatory cytokines on the L-selectin surface expression on PMN. Twenty patients admitted to our institution for elective operations of the lower extremities were enrolled in a prospective clinical study. For the measurement of L-selectin expression, blood was taken before the operation (0 h), as well as 24 h and 48 h postoperatively. Without and after incubation with different pro- and anti-inflammatory cytokines (TNF-α, IL-1β, IL-6 and IL-10), the surface expression of L-selectin was detected using an anti-L-selectin-specific antibody and flow cytometry. L-selectin surface expression without any stimulation showed a non-significant increase 48 h after the operation (63.6±6.6 ng/ml at 0 h, 95.2±10.5 ng/ml at 48 h). Stimulation with TNF-α resulted in a significant decrease of L-selectin expression at 0 h (25.6±2.7 ng/ml; p<0.05) and 24 h (18.3±2.5 ng/ml; p<0.05), but not at 48 h (39.8±4.2 ng/ml). No significant differences were observed after stimulation with IL-1β, IL-6, and IL-10 in comparison to the non-stimulated group. The study results indicate that the primary pro-inflammatory cytokine TNF-α regulates the L-selectin surface expression on PMN after surgical trauma. Therefore, a regulation of neutrophil activation on this level might be crucial in the development of posttraumatic complications.

Neutrophil phenotype and function in partial hepatectomy in man

PURPOSE

Hepatic resections are still associated with considerable morbidity mainly because of postoperative infection. Adequate function of neutrophils is a crucial element in host defense. The aim of the study was to characterize neutrophils during partial hepatectomy.

METHODS

Fourteen patients undergoing partial liver resection were enrolled. Twenty-four hours pre-, intra- (after induction of anesthesia, after preparation of the liver, and 15 min after release of the Pringle maneuver), as well as postoperatively (3 h after Pringle; 24, 48, and 120 h after surgery), blood samples were obtained. In addition, healthy volunteers (n = 5) were investigated. Adhesion molecules (CD 62, CD 18), Fcy receptors (CD 16, CD 32), and phagocytosis by neutrophils were characterized by fluorescence-activated cell sorter analysis. Spontaneous and stimulated (formyl-methionyl-leucyl-phenylalanine) oxygen radical generation was measured by lucigenin-enhanced chemiluminescence.

RESULTS

Numeric upregulation of CD 62 and CD 18 on neutrophils was seen before the use of Pringle maneuver and persisted thereafter (p < 0.05). Spontaneous numeric expression of Fcy receptors (CD16 and CD 32) was unchanged during liver dissection but downregulated after Pringle maneuver was opened (p < 0.05). Although numeric Fcy receptors were downregulated, phagocytosis of heterologous opsonized Escherichia coli bacteria by neutrophils was unaffected. Spontaneous oxygen radical production peaked sharply 15 min after release of the Pringle maneuver (p < 0.05), contrary to stimulated oxygen radical production, which was depressed 3 h after the release of the Pringle maneuver (ns).

CONCLUSIONS

Uneventful partial hepatectomy in man resulted already in a significant change in the phenotype but in less significant changes in the functions of neutrophils.

The systemic inflammatory response induced by trauma is reflected by multiple phenotypes of blood neutrophils

Secondary morbidity and mortality after trauma are mainly due to a dysfunctional immune system. Severe injury can trigger a systemic inflammatory response, which is characterised by pre-activation or priming of neutrophils in peripheral blood. Signals initiated as result of local tissue damage can further activate these neutrophils leading to post-injury inflammatory complications. Additional trauma caused by surgical intervention can worsen the inflammatory response, thereby increasing the risk of these inflammatory complications. Limiting surgical procedures through damage control principles can reduce the risk of secondary morbidity. Inflammatory complications after injury cannot adequately be predicted using the current anatomical and physiological-based scoring systems. In this review we propose a methodology focussing on the activation state of the systemic inflammatory response with focus on neutrophils to aid in the risk assessment of secondary morbidity after trauma. Neutrophils are essential effector cells during the post-injury systemic inflammatory response. Neutrophils differentially express an array of surface receptors by which the cells can respond and adapt to changing environmental signals. The determination of specific expression profiles of neutrophil receptors can aid in phenotyping and quantifying the systemic inflammatory response. This article reviews the application of these specific signatures of neutrophil receptors as a consequence of severe injury.

Quantification and characterisation of endothelial injury after trauma

The microenvironment theory has become very popular for providing mechanisms which explain the development of often lethal posttraumatic complications such as systemic inflammatory response syndrome (SIRS), adult respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS). With the recent advances in molecular biology and the ever-expanding understanding of trauma pathophysiology, immunomonitoring in trauma patients attempts to characterise and quantify novel molecules in order to predict patients at risk. This review article assesses the existing evidence on the biomarkers of endothelial injury and their potential utility as quantification parameters of endothelial dysfunction in trauma patients.

Granulocyte activation in humans is modulated by psychological stress and relaxation

Our aim was to study the possible relationship between psychological stress and granulocyte activation primarily in healthy students during an examination period (n = 11) and also in chronically anxious patients (n = 15). We employed cell surface markers: lactoferrin, L-selectin, alphaMbeta2-integrin and CD15s and flow cytometry to detect changes in the activation state of granulocytes, with the start of the stressed state in students at the beginning of an examination period, which was associated with elevated blood plasma cortisol level, and following relaxation hypnosis in both students, during their examination term, and patients. The ratios of all four types of marker-carrier granulocytes increased at the start of the examination period in students; an especially dramatic (ca. 5-fold) enhancement was observed in the proportion of lactoferrin-bearing cells relatively to the pre-examination term value. After hypnosis, the percentage of lactoferrin-exposing granulocytes decreased considerably both in students and in patients, by about half; a similar decrease was observed in the ratio of CD15s-carrier cells in patients. No significant alteration was observed during the study in state or trait anxiety levels, and in total or differential leukocyte counts. Thus, granulocyte activation could be associated with stress, while relaxation may facilitate reducing activation of these cells. In both groups of subjects, granulocyte surface lactoferrin appeared to be a sensitive "stress indicator". This needs further evaluation.

Adhesion molecules and cytokine expression in fibromyalgia patients: increased L-selectin on monocytes and neutrophils

Several lines of evidence implicate the immune system in the pathophysiology of fibromyalgia (FM). We investigated the role of cytokines and adhesion molecules involved in immune cell trafficking and the influence of 1.5 mg of dexamethasone (DEX) per os on their expression. L-selectin was elevated on monocytes and neutrophils of FM patients. Differences in group response to DEX were observed for CD11b on NK cells, sICAM-1 and IL-2. This study shows a slight disturbance in the innate immune system of FM patients, and suggests an enhanced adhesion and recruitment of leukocytes to inflammatory sites.

Intraoperative splanchnic hypoperfusion, increased intestinal permeability, down-regulation of monocyte class II major histocompatibility complex expression, exaggerated acute phase response, and sepsis

BACKGROUND

A compromised gut barrier function may be associated with systemic inflammatory response syndrome, sepsis, and multiple organ dysfunction syndrome in patients after major trauma or critical illness, and inadequate oxygenation of the gut mucosa has been incriminated as an underlying mechanism. The focus of this study was the relationship of splanchnic hypoperfusion to regional and systemic immune responses after major surgery.

METHODS

Patients (n=20) undergoing curative oncologic resection of the esophagus or esophagogastric junction were studied. Gastric mucosal pH level was monitored by gastric tonometry. The expression of class II major histocompatibility complex antigen (human leukocyte antigen-DR) and L-selectin on systemic monocytes was assessed before surgery, during surgery (as well as portal monocytes), and for 1 week after surgery, along with C-reactive protein levels. Intestinal permeability was measured before surgery and on the first and seventh postoperative days by using dual sugar probes.

RESULTS

Significant mucosal acidosis (pH<7.1) intraoperatively was evident in 5 patients (25%), and a further 7 patients (35%) had a nadir gastrointestinal mucosal pH level between 7.1 and 7.2. Severe (<7.1) mucosal acidosis was associated significantly (P< .05) with postoperative septic complications, an increase in postoperative intestinal permeability, C-reactive protein and L-selectin expression, and a decrease (P< .05) in monocyte human leukocyte antigen-DR expression.

CONCLUSIONS

Intraoperative splanchnic hypoperfusion is associated significantly with down-regulation of monocyte function, increased intestinal permeability, and an exaggerated acute phase response. This suggests that splanchnic hypoperfusion alters local and systemic immune function, supporting the thesis that the gut has a central role in the immunoinflammatory response to major surgery.

L-selectin: adhesion, signalling and its importance in pathologic posttraumatic endotoxemia and non-septic inflammation

The leucocyte expressed surface-bound L-selectin belongs to the selectin family of adhesion molecules. It exhibits adhesive as well as signalling functions. Mainly, it is of importance in lymphocyte homing and in the extravasation of leucocytes into the surrounding tissue during inflammation. Acting in the initial step of the cell adhesion cascade, L-selectin is responsible for the rolling of leucocytes on endothelial layers. Therefore, L-selectin is thought to be an adequate target for pharmacological interventions. Beneath the discussion of the molecules' general features like molecule structure and its regulation, the review focuses firstly on L-selectin in the context of posttraumatic inflammatory disorders, and secondly on the importance of L-selectin specific signalling events.

L-selectin shows time and gender dependency in association with MODS

BACKGROUND

Recent investigations have demonstrated gender related immunologic alterations after trauma. These complications arise due to polymorphonuclear granulocytes (PMN) interacting with endothelium via L-selectin. Therefore, the purpose of this study was to investigate gender related differences in the expression of L-selectin in relation to posttraumatic multiple organ dysfunction syndrome (MODS).

METHODS

Multiply injured patients were prospectively entered in the study. MODS was determined using the Denver score. The concentration of L-selectin on the surface of PMN was determined using flow cytometry during a 14 days' period.

RESULTS

48 patients were included in the study. The kinetics of L-selectin were different comparing male and female patients. Male patients with MODS initially showed a rapid decrease of surface L-selectin from 80 to 20 ng/ml. A return to admission levels was related to MODS. Male patients without MODS displayed elevated L-selectin levels up to 140 ng/ml. Female patients, however, all showed an initial rapid decrease of L-selectin to 20 ng/ml. Women who developed posttraumatic MODS had significantly increased levels up to 110 ng/ml before development of MODS developed.

CONCLUSIONS

We feel that a gender related dimorphism in the initial L-selectin expression following trauma exists and is associated with MODS. These findings indicate new therapeutic means for the treatment of MODS. Therapies should be timely and gender dependently coordinated.

Adhesion molecules, catecholamines and leucocyte redistribution during and following exercise

The circulating blood normally contains no more than 1-2% of the body's population of leucocytes. The numbers and phenotypes of circulating leucocyte subsets can change dramatically during and immediately following exercise. The surface expression of adhesion molecules makes an important contribution to such responses by changing patterns of cell trafficking. Alterations in the surface expression of adhesion molecules could reflect a shedding of molecules, selective apoptosis or differential trafficking of cells with a particular phenotype, effects from mechanical deformation of the cytoplasm, active biochemical processes involving cytokines, catecholamines, glucocorticoids or other hormones, or changes in the induction of adhesion molecules. The expression of adhesion molecules changes with maturation and activation of leucocytes. Typically, mature cells express lower densities of L-selectin (CD62L), the homing receptor for secondary lymphoid organs, and higher densities of LFA-1 (CD11a), the molecule associated with trafficking to non-lymphoid reservoir sites. The neutrophils and natural killer cells that are mobilised during exercise also express high levels of Mac-1 (CD11b), a marker associated with cellular activation. Possibly, exercise demarginates older cells that are awaiting destruction in the spleen. Plasma concentrations of catecholamines rise dramatically with exercise, and there is growing evidence that catecholamines, acting through a cyclic adenosine monophosphate second messenger system, play an important role in modifying the surface expression of adhesion molecules. Analogous changes can be induced by other forms of stress that release catecholamines or by catecholamine infusion, and responses are blocked by beta(2)-blocking agents. Catecholamines also modify adherence and expression of adhesion molecules in vitro. Cell trafficking is modified by genetic deficiencies in the expression of adhesion molecules, but leucocyte responses to exercise and catecholamines are generally unaffected by splenectomy. A number of clinical conditions including atherogenesis and metaplasia are marked by an altered expression of adhesion molecules. The effects of exercise on these molecules could thus have important health implications.

Increased production of leukocyte microparticles with enhanced expression of adhesion molecules from activated polymorphonuclear leukocytes in severely injured patients

BACKGROUND

Polymorphonuclear leukocyte (PMNL)-derived microparticles (MPs) have been recently reported as activators of vascular endothelium in vitro. The objectives of the present study were to evaluate the production of MPs in severely injured patients and to clarify the role of these MPs.

METHODS

Thirty severely injured patients (mean Injury Severity Score of 27 +/- 11) and 21 healthy volunteers participated in the study. Blood samples were obtained serially at three time points: days 0 to 1, days 2 to 5, and days 6 to 12 after the trauma event. MP production, CD11b and CD62L expression on MPs, and oxidative activity in PMNLs were measured by flow cytometry in both the presence and absence of formylmethionyl-leucyl-phenylalanine. Expressions of CD11b and CD62L were differentially evaluated according to the size of the MPs (>or= or < 1.0 microm). Soluble E-selectin and thrombomodulin levels in blood, variables representative of systemic vascular endothelial damage, were also measured.

RESULTS

Production of MPs with and without formylmethionyl-leucyl-phenylalanine and the oxidative activity in PMNLs (O ) were prominently increased on days 2 to 5 after trauma. CD62L expression was enhanced on MPs at all three time points, and CD11b expression was enhanced on MPs < 1.0 microm in diameter at all three time points. Soluble E2-selectin and thrombomodulin in blood did not change significantly between time points.

CONCLUSION

Activated PMNLs enhance production of PMNL-derived MPs with increased adhesion molecule expression on days 2 to 5 after severe trauma. This response per se, however, may not progress to systemic vascular endothelial damage.

Effect of stress hormones on the expression of fibrinogen-binding receptors in platelets

Acute coagulopathy is a common clinical complication after trauma, and contributes to posttraumatic multiple organ failure. The phenomenon may be due to the effect of stress hormones on platelet adhesion molecule expression after trauma. Catecholamine levels correlate with injury severity scores and changes of L-selectin expression on leucocytes, whilst adrenaline (ADR) (epinephrine) alone also activates platelets. This study thus investigates the effects of ADR and noradrenaline (NOR) (norepinephrine) on platelets, at doses similar to those found in the plasma of normal and trauma subjects. Blood was taken from 19 healthy subjects and placed in tubes containing sodium citrate. Anti-platelet-bound fibrinogen monoclonal antibody was used to identify the activated platelets while anti-CD41 was used to identify platelets with and without activation. Five increasing concentrations of ADR and NOR (1, 3, 5, 10, 30 nmol/l) as well as one negative control (0.9% normal saline) and one positive control (10 micromol/l adenosine diphosphate/ADP) were prepared for the stimulation. A whole blood protocol was used in order to minimize any activation artefacts, which might be created by centrifugation. The percentage of platelets expressing fibrinogen receptors increased significantly with ADR and NOR even at the lowest dose (1 nmol/l) and continued to increase in a dose-dependent manner. Although the effect of ADR was greater than NOR in stimulating platelets to express fibrinogen receptors, the average number of fibrinogen receptors on each platelet was constant. ADR and NOR activated platelets to express fibrinogen receptors at doses that are similar to those found in the plasma of trauma patients.

Soluble L-selectin attenuates tumor necrosis factor-alpha-mediated leukocyte adherence and vascular permeability: a protective role for elevated soluble L-selectin in sepsis

OBJECTIVE

We have previously demonstrated that leukocyte delivery to remote sites is decreased in sepsis and that increased concentrations of soluble L-selectin are, in part, responsible for this finding. Given that leukocytes have been implicated in the pathogenesis of vascular leakage, we hypothesized that the elevated soluble L-selectin concentrations in sepsis may translate into decreased inflammation-mediated leukocyte-endothelial cell interactions and vascular leakage at these sites.

DESIGN

Prospective, controlled animal study.

SETTING

Surgical research laboratory in a university hospital.

SUBJECTS

Swiss white male mice weighing 25-35 g.

INTERVENTIONS

Mice were randomized to one of three study groups: intracremaster tumor necrosis factor-alpha with subsequent intravenous bicarbonate buffered solution; intracremaster tumor necrosis factor-alpha with intravenous soluble L-selectin (10 microg/mL); and intracremaster bicarbonate buffered solution with intravenous bicarbonate buffered solution. The cremaster muscle was prepared for both light and fluorescence intravital microscopy 2 hrs after intracremaster injection, and fluorescein isothiocyanate-labeled albumin was injected intravenously. Leukocyte-endothelial interactions (rolling flux, rolling velocity, and adherence) were counted off-line. Postcapillary venule leakage was determined by the permeability index (perivenular/intravenular fluorescence) after intravenous injection of fluorescent albumin.

MEASUREMENTS AND MAIN RESULTS

Soluble L-selectin significantly attenuated tumor necrosis factor-alpha-mediated increases in leukocyte adherence and vascular leakage. Leukocyte rolling velocity was restored to baseline with soluble L-selectin; however, rolling flux was not altered. Blood pressure, shear rate, and leukocyte counts did not differ between groups.

CONCLUSIONS

Soluble L-selectin decreases local inflammation-mediated leukocyte adherence and vascular leakage in vivo. The increased concentrations of soluble L-selectin in sepsis may represent a protective mechanism by which the host attempts to diminish the deleterious systemic effects of activated leukocytes during sepsis.

Epinephrine as a mediator of pulmonary neutrophil sequestration

Neutrophil-mediated lung injury is a potential complication of trauma and sepsis. Concomitant with trauma and sepsis, there is an immediate and sustained systemic elevation of catecholamines including epinephrine. In the absence of trauma or sepsis, we examined whether epinephrine contributes to the accumulation of neutrophils in the lung. Eight- to 12-week-old male CF-1 mice were injected i.p. with 0.2 mL of normal saline or epinephrine (0.1-5.0 mg/kg). An unmanipulated control group was included to examine the stress of i.p. injection. Animals were sacrificed at predetermined time points, and lung and spleen were harvested. PMN accumulation was assessed by using a myeloperoxidase (MPO) assay, which is an indirect marker for neutrophil presence. Morphometric analysis of lung tissue was performed by a pathologist blinded to the groups. Increasing epinephrine doses resulted in a significantly increased accumulation of pulmonary neutrophils compared with normal saline. The stress of normal saline injection also resulted in a significantly greater pulmonary neutrophil accumulation than unmanipulated controls. The effects of epinephrine on pulmonary neutrophil accumulation were greatest at 2 h, but they were not significantly different from saline-injected controls by 12 h. These results correlated with histological analysis. There were no significant differences in spleen MPO activity between groups, suggesting an organ-specific mechanism of epinephrine-induced pulmonary neutrophil sequestration. In the absence of trauma, shock, or infection, epinephrine results in the accumulation of neutrophils in murine lungs. The finding that "injection stress" increased lung neutrophil sequestration suggests the possibility that this mechanism may be physiologically relevant. Thus, epinephrine release in trauma may set the stage for development of neutrophil-mediated acute lung injury.

Role of L-selectin in the development of ventilator-associated pneumonia in patients after major surgery

BACKGROUND

The circulating level of soluble L-selectin (sL-selectin) has been reported to be low in adult respiratory distress syndrome and acute lung injury. This study explores the role of L-selectin in the development of ventilator-associated pneumonia (VAP) in patients undergoing major surgery.

PATIENTS AND METHODS

Thirty-four patients who underwent esophagectomy were maintained by mechanical ventilation in a surgical intensive care unit. Fourteen patients developed VAP by postoperative day (POD) 7, while 20 patients did not. The plasma levels of soluble adhesion molecules and elastase were measured serially by ELISA or EIA. The expression of L-selectin on polymorphonuclear neutrophils (PMNs) was analyzed by flow cytometry.

RESULTS

In multiple logistic regression analysis, only the preoperative plasma level of sL-selectin was significantly associated with VAP. The plasma sL-selectin level before surgery was significantly lower in the patients who developed VAP compared with the patients who did not develop VAP. After surgery, the level of sL-selectin did not change. The plasma level of soluble intercellular adhesion molecule-1 increased in the patients with and without VAP. The plasma level of soluble vascular cell adhesion molecule-1 was significantly higher in the patients with VAP. L-selectin expression on PMNs showed a peak on POD 2 in the patients without VAP, whereas it was impaired in the patients with VAP.

CONCLUSIONS

Determination of the preoperative plasma level of sL-selectin may help to identify patients at high risk for VAP after esophagectomy.

L-selectin in health and disease

This article reviews recent advances in the knowledge of the role of L-selectin, an adhesion molecule that is expressed on the surface of circulating leucocytes, in animal and human physiology and pathophysiology. After a brief discussion on nomenclature and structure, it progresses through the evidence for expression and regulation of L-selectin, cell collection and purification, physiological function and roles. The special role of knock out mice and monoclonal antibodies in determining a role for L-selectin in inflammatory states is described before proceeding to discuss the importance of L-selectin ligands and shed L-selectin. A second section describes a role for L-selectin in pathophysiological states in animals and man, with special reference to trauma, systemic inflammatory syndromes and sepsis. The review concludes with a summary of the potential role of anti-inflammatory medication and L-selectin blockers in the management of inflammation.

Humoral markers of severity and prognosis of critical illness

Despite the considerable advances made in understanding the pathophysiology of systemic inflammation during critical illness, clinical progress has been elusive as it remains a very deadly condition. Cortisol and thyroid hormone levels can be as predictive of outcome as the commonly used severity parameters (i.e. APACHE). Indeed, levels of endocrine humoral substances such as arachidonic acids, nitric oxide, endothelin, calcitonin precursors, leptin and adenosine correlate with the severity and outcome of critical illness. Furthermore, calcitonin precursors represent a potentially new hormokine paradigm, being transcriptionally activated in all cells in response to infection. The cytokines are immune markers that often correlate with severity and outcome, but their release is transient. In contrast, the so-called acute phase proteins, such as C-reactive protein and serum amyloid A, are highly sensitive to inflammatory activity and can be important markers of severity and outcome. Leukocyte esterase, adhesion molecules, platelet activating factor and activated protein C are additional humoral immune markers; the replacement of the latter has been shown to be a promising therapeutic option. Natriuretic peptides are neurocrine humoral markers that have important cardiovascular implications. The level of macrophage migrating inhibitory factor, released by the pituitary, is elevated in sepsis and counteracts glucocorticoid action. Cellular markers to severe stress include the enhanced expression of protective substances in the form of heat shock proteins. High mobility group-1 is a DNA-binding protein and a late mediator of the inflammatory response. Apoptotic markers such as the soluble fas ligand are also elevated in inflammation. In summary, during critical illness, the endocrine, immune and nervous systems elaborate a multitude of humoral markers, the roles of which merit further scrutiny in order to improve therapeutic outcome.

Cantharidin blisters: a technique for investigating leukocyte trafficking and cytokine production at sites of inflammation in humans

A skin blister technique is described which allows the investigation of acute inflammation in humans in vivo. Filter paper discs are placed on the skin, impregnated with cantharidin and covered with impermeable film held by adhesive tape. The assembly is easily applied, unobtrusive, stable and may be worn during normal activities. The blister formed at 24 h contains approximately 5x10(5)-5x10(6) cells, predominantly neutrophils and macrophages. Inflammatory cytokines and chemotactic factors are detectable in the blister fluid. The technique is useful for characterizing the acute inflammatory response in health and disease.

Role of monocyte L-selectin in the development of post-traumatic organ failure

The vascular leucocyte adhesion molecule, L-selectin, plays an important early role in monocyte trafficking at sites of inflammation, a process which leads to the development of inflammatory organ failure. In this prospective observational study, we investigate whether early numerical and functional changes in circulating monocytes, expression of monocyte L-selectin (CD62L) and monocyte:neutrophil L-selectin ratios are related to the subsequent development of post-traumatic organ failure (OF) and multiple organ dysfunction syndrome (MODS). Monocyte counts and cell surface L-selectin were measured by an automated cell counter and flow cytometry, respectively. Of 164 trauma patients admitted to a university emergency department resuscitation room, 64 had multiple injuries, 51 developed OF, 20 developed MODS and 21 died. Early monocyte counts in patients with multiple injuries were lower in those who developed MODS (0.44 x 10(9)/l) compared with those who did not (0.60 x 10(9)/l; P=0.024). Monocyte L-selectin mean channel fluorescence increased with injury severity and was highest in those who developed MODS (P=0.033). In the sub-group of patients with multiple injuries, L-selectin mean channel fluorescence was also greater in those patients who developed MODS compared with patients who did not develop MODS (P=0.042). The monocyte to neutrophil count ratio also decreased with injury severity (P=0.006). Using optimal cut off values for L-selectin mean channel, fluorescence, the positive and negative predictive values for OF was 43.5 and 91.4%, respectively and for MODS it was 25.4 and 92.9%, respectively. Alterations in early circulating monocyte counts and L-selectin expression after injury are related to the development of post-traumatic organ failure and suggest an area in the inflammatory pathway that may be influenced by L-selectin blockade.

Shed L-selectin (sCD62L) load in trauma patients

BACKGROUND

Low circulating plasma concentrations of the leukocyte adhesion molecule L-selectin (sCD62L) were found to be associated with an increased risk for subsequent lung failure and case fatality after severe trauma. The objective of this study was to determine the robustness of soluble L-selectin, correcting for a broad spectrum of physiological variables.

METHODS

Patients with suspected multiple and/or trunk injuries were enrolled into this study over a 1-year period. Plasma samples were obtained on hospital presentation, and circulating soluble L-selectin was measured with a commercially available ELISA kit. Study records comprised all relevant clinical and laboratory data. Thirty-day survival rate, subsequent acute lung failure, and nosocomial pneumonia were defined as study endpoints. Statistical analysis was performed using multivariate logistic regression models.

RESULTS

Seventy patients with a mean age of 35.51 years (range, 10-87 years) and a mean ISS score of 36.61 (95% CI, 31.08-42.14) entered the study. Eleven patients died, leading to an attributable mortality of 15.70%. L-Selectin levels did not differ between survivors and nonsurvivors. Five patients progressed to acute lung injury, whereas 11 patients developed hospital-acquired pneumonia. Lower L-selectin levels indicated patients at risk for lung injury with a relative odds estimated at 4.43 (P = 0.017). Statistical significance diminished in the multivariate model. In contrast, plasma concentrations of circulating sCD62L were significantly decreased in patients developing nosocomial pneumonia (P = 0.023), with a twofold increased relative odds (OR, 1.96; 95% CI, 0.51-7.50). No effect modification was observed by the included covariables.

CONCLUSIONS

The results of this study highlight the independent predictive value of initially decreased soluble L-selectin levels for the identification of patients susceptible to subsequent respiratory complications after severe trauma.

Soluble L-selectin at levels present in septic patients diminishes leukocyte-endothelial cell interactions in mice in vivo: a mechanism for decreased leukocyte delivery to remote sites in sepsis

OBJECTIVE

Recent in vivo studies of both septic humans and animals demonstrate that leukocyte delivery is attenuated to sites remote from the primary infection. The mechanisms for this are not entirely clear. L-selectin is integral to rolling, the first step in leukocyte recruitment to an inflammatory site. L-selectin is shed from leukocytes in sepsis, resulting in increased levels of soluble L-selectin in plasma (2.33 microg/mL). This study investigates the effects of soluble L-selectin at levels found in sepsis on leukocyte trafficking in vivo.

DESIGN

Prospective, controlled trial.

SETTING

Surgical research laboratory in a university hospital.

SUBJECTS

Swiss white male mice of 25-35 g.

INTERVENTIONS

Mice were randomized to one of three study groups: soluble L-selectin 2.33, soluble L-selectin 8.0, or albumin. Intravital microscopy was performed on postcapillary venules of 20-40 microm in diameter in the cremaster muscle of mice. Leukocyte-endothelial cell interactions (rolling, adherence, and rolling velocity) were measured pre- and post- (1, 15, 30, and 45 mins) intravenous infusion of human recombinant soluble L-selectin (2.33 and 8.0 microg/mL) or human albumin (8.0 microg/mL).

MEASUREMENTS AND MAIN RESULTS

The intravenous administration of soluble L-selectin to a systemic concentration of 2.33 microg/mL diminished rolling significantly. Soluble L-selectin at 8.0 microg/mL decreased rolling and increased rolling velocity to a greater degree. Injection of albumin did not alter leukocyte-endothelial cell interactions at any time point. No difference between groups in blood pressure, shear rate, or leukocyte counts was detected.

CONCLUSIONS

Soluble L-selectin diminishes leukocyte rolling at levels present in sepsis (2.33 microg/mL). This effect is dose dependent, and could not be explained by differences in blood pressure, shear rate, or leukocyte counts. These findings identify increased soluble L-selectin levels as one of the mechanisms for decreased leukocyte delivery and exudation to remote sites in septic patients.

Early role of neutrophil L-selectin in posttraumatic acute lung injury

OBJECTIVE

To investigate whether early numerical and functional changes in circulating neutrophils and expression of neutrophil L-selectin and soluble L-selectin are related to the subsequent development of posttraumatic acute lung injury (ALI), the systemic inflammatory response syndrome, sepsis, and organ failure.

DESIGN

Prospective study of whole blood and plasma samples to assess numerical and functional changes in circulating neutrophils and in soluble L-selectin.

SETTING

The emergency department of a university hospital.

PATIENTS

A total of 147 patients admitted to the resuscitation room after trauma were compared with 69 control subjects. Ten patients developed ALI.

LABORATORY ANALYSIS

Flow cytometry of whole blood and ELISA of plasma.

RESULTS

Total leukocyte and neutrophil counts, expression of L-selectin, and the ratio of neutrophil to plasma L-selectin increased with injury and were highest in those who developed ALI. Soluble L-selectin decreased with injury severity and was lowest in those who developed ALI.

CONCLUSIONS

Early changes in the average expression of L-selectin per cell do not correlate with the development of subsequent posttraumatic ALI. However, the development of ALI is related to the total expression of L-selectin in the neutrophil mass, and the most striking association is in those with lower concentrations of plasma L-selectin.

Increased plasma free cyclic-AMP levels following major trauma and their relevance to the immune response

BACKGROUND

Following injury, neutrophil mobilisation is an important element of the immune response. The ideal features of an agent responsible for this mobilisation would include the ability to mobilise neutrophils without activating them, and rapid reversibility. This study investigates the hypothesis that raised levels of plasma adrenaline following trauma act via cyclic adenosine monophosphate (cAMP) to mobilise neutrophils, and measures the amount of cAMP extruded from cells into the plasma following injury.

METHODS

20-ml samples of venous blood were drawn from 34 trauma patients within 3 h of injury and divided between three sample tubes: (1) ethylene diamine tetra-acetic acid anticoagulant (EDTA) for full blood count; (2) cooled EDTA for cAMP levels; and (3) cooled lithium heparin for catecholamines. The latter two tubes were immediately centrifuged at low temperature and the supernatant plasma deep frozen pending analysis. Adrenaline was measured using high pressure liquid chromatography (HPLC) and cAMP measured by an enzyme immunoassay technique.

RESULTS

34 patients, six of whom had sustained minor trauma (ISS 1-8), 12 moderate trauma (ISS 9-15) and 16, major trauma (ISS 16 and above) were studied. Median age was 39 years (range 16-77) and 30 patients were male. Plasma adrenaline levels were available for 28 of the patients. Plasma free cAMP levels were significantly raised in patients with major trauma (P < 0.006). There were positive correlations between the plasma levels of cAMP and adrenaline (rho 0.660, P = 0.011), adrenaline and neutrophil count (rho 0.654, P = 0.01) and cAMP and neutrophil count (rho 0.508, P = 0.013).

CONCLUSIONS

Evidence is presented of the possible inter-relationships between neutrophil counts, adrenaline levels and cAMP levels following injury, supporting the proposition that neutrophil mobilisation pathways are activated early via beta-adrenergic stimulation.

L-selectin in trauma patients: a marker for organ dysfunction and outcome?

BACKGROUND

Systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) are important factors affecting morbidity and mortality after trauma. Adhesion molecules, e.g. L-selectin (CD62 L), play crucial roles in both conditions.

PATIENTS AND METHODS

In 51 multiple trauma patients, CD62 L surface expression on granulocytes, monocytes, lymphocytes, as well as sCD62 L plasma concentrations were determined during the first 6 days after trauma, starting at the site of accident. Clinical parameters were severity of injury scores (ISS, APACHE II), requirement of red blood cell transfusion, acute lung or liver failure, development of MODS or SIRS, early (< or = 6 d) or late (> 6 d), and outcome.

RESULTS

CD62 L expression was reversibly elevated on granulocytes, T cells and monocytes in comparison with initial values. sCD62 L plasma concentrations did not show temporal variations but were depressed throughout observation period, in comparison with healthy controls. Lung failure within the first 6 days was associated with increased CD62 L expression on monocytes and B cells on admission and increased sCD62 L concentrations after 12 and 24 h. Patients with more severe injuries (APACHE II > 20 points) had higher sCD62 L concentrations after 24 h. Non-survivors had decreased sCD62 L (on admission) and T-cell CD62 L expression (after 4 h). Patients with early MODS or SIRS showed increased monocyte CD62 L expression after 6 days.

CONCLUSIONS

In multiple trauma patients, severe organ dysfunction is associated with altered CD62 L expression on leukocytes and circulating sCD62 L plasma concentrations. However, the obvious complexity of the pattern currently restricts use of CD62 L quantitation for clinical purposes.

Adrenaline upregulates monocyte L-selectin in vitro

OBJECTIVE

Although surface adhesion molecules mediate leucocyte-endothelial interactions at sites of inflammation, relatively little is known of the factors which increase the expression of L-selectin in circulating leucocytes. The expression of leucocyte L-selectin increases during acute stress events such as injury and is temporally related to an early neuroendocrine response. This study investigates whether adrenaline increases the expression of L-selectin on monocytes, neutrophils and lymphocytes in vitro and whether these effects are mediated via beta-adrenoceptors.

METHODS

A total of 20 ml of blood was withdrawn from 28 healthy volunteers (21 males) with a mean age of 29 years (range 23-67 years). Adrenaline at physiological doses mimicking trauma (0-200 nmol/l) was added to whole blood prior to immunofluorescent staining and analysis by flow cytometry. Propranolol (50 microl of 2 x 10(-5) M) was also added to separate tubes prior to incubation with adrenaline. Saline (40 microl 0.9% solution) was used as a control. Expression is described firstly as percentage of cells expressing L-selectin and secondly as average intensity (mean channel fluorescence, mcf) per cell expressing CD62L. Summary measures were used to analyse the data.

RESULTS

A significant increase in both the percentage of monocytes expressing L-selectin and mean channel fluorescence of L-selectin was evident with adrenaline in vitro (P < 0.0001). Maximal increases occurred at 100 nmol/l adrenaline when a 9% increase in the percentage of monocytes expressing L-selectin and a 23% increase in mean channel fluorescence were observed. These effects were both blocked by propranolol (P < 0.0001). No significant differences were observed for neutrophils or lymphocytes except for a slight increase in the percent neutrophils expressing L-selectin, and a small decreasing trend in percent lymphocytes expressing L-selectin.

CONCLUSIONS

Adrenaline upregulates the surface expression of L-selectin on monocytes in vitro, an effect which is partially mediated by beta-adrenoceptors. As monocytes initiate early aspects of the inflammatory response, these findings suggest that beta-blockade may have an inhibitory role for certain aspects of leucocyte trafficking.

Do peripheral blood counts have any prognostic value following trauma?

BACKGROUND

Both lymphocytosis and lymphopenia have been observed following trauma and each has been claimed to predict mortality. An understanding of the early temporal changes in leucocyte counts may help to explain why such discrepancies have been found. The purpose of this study was to determine the early serial changes in peripheral leucocyte counts following injury.

METHODS

A whole blood cell counter was used to measure serial total leucocyte, granulocyte, lymphocyte and monocyte counts from 20 patients in the first 3 h following blunt injury. Four to six peripheral blood samples were taken from each subject and grouped into 20 min intervals.

RESULTS

Granulocytosis, lymphocytosis and monocytosis were evident within 40 min of injury. A biphasic granulocyte and monocyte response was observed in the first 3 h following trauma. Lymphocytes showed a linear resolution towards normal (regression coefficient -0.022; p < 0.01) with some individuals developing a lymphopenia. No correlation with injury severity was observed.

CONCLUSION

Rapid mobilisation and subsequent redistribution of leucocytes occurs early following injury. Temporal changes will affect any predictive value of circulating leucocytes and studies must be precise with respect to blood sampling time.