Correlation between serum level of soluble L-selectin and leukocyte count in chronic myeloid and lymphocytic leukemia and during bone marrow transplantation

Dynamic changes in the levels of sCD62L and SPARC in chronic myeloid leukaemia patients during imatinib treatment

WHAT IS KNOWN AND OBJECTIVE

Chronic myeloid leukaemia (CML) microenvironment is responsible for resistance of leukaemic cells to tyrosine kinase inhibitor, altered adhesion, increased proliferation and leukaemic cells growth and survival through the secretion of many soluble molecules. We aimed at monitoring soluble L-selectin (sCD62L) and secreted protein acidic and rich in cysteine (SPARC) levels in chronic phase chronic myeloid leukaemia (CP-CML) patients and assessing the impact of imatinib on these parameters.

METHODS

This prospective controlled clinical trial enrolled 35 subjects classified into two groups: control group included 10 healthy volunteers and CP-CML patients group included 25 newly diagnosed CP-CML patients received imatinib 400 mg once daily. sCD62L plasma levels, SPARC serum levels, breakpoint cluster region-Abelson1 (BCR-ABL1) %, complete blood count with differential, liver and kidney functions parameters were assessed at baseline and after 3 and 6 months of treatment.

RESULTS AND DISCUSSION

At baseline, sCD62L and SPARC were significantly elevated in CP-CML patients (p < 0.05) compared to control group. After 3 months of treatment, sCD62L was non-significantly decreased (p > 0.05), while surprisingly SPARC was significantly increased (p < 0.05) compared to baseline. Moreover, after 6 months of treatment, sCD62L was significantly decreased (p < 0.05) and SPARC was non-significantly decreased (p > 0.05) compared to baseline. In addition, sCD62L was significantly correlated with WBCs and neutrophils counts, while SPARC was significantly correlated with lymphocytes count at baseline and after 3 and 6 months of imatinib treatment.

WHAT IS NEW AND CONCLUSION

The elevated levels of sCD62L and SPARC at diagnosis in CP-CML patients could reflect their roles in CML pathogenesis and the dynamic changes in their levels during imatinib therapy might suppose additional mechanisms of action of imatinib beside inhibition of BCR-ABL. Furthermore, imatinib showed a significant impact on sCD62L and SPARC levels during treatment period.

Circulating P-, L- and E-selectins in pseudoxanthoma elasticum patients

OBJECTIVES

Pseudoxanthoma elasticum (PXE) is a hereditary disorder predominantly affecting the skin, retina and vascular system. The aim of this study was to measure cell adhesion molecules in PXE patients.

DESIGN AND METHODS

Soluble P-, E- and L-selectins were measured in 61 non-consanguineous PXE patients. The distribution of the variants E-selectin S128R and P-selectin T715R were determined.

RESULTS

P-selectin concentrations were significantly increased in male and female PXE patients. Furthermore, P-selectin levels correlated with the ABCC6 gene status of the PXE patients. Patients harboring two mutant ABCC6 alleles had 1.5-fold increased P-selectin concentrations in comparison to patients with at least one wild-type allele. E- and L-selectin levels were within normal range and the allelic frequencies of the investigated polymorphisms did not differ between patients and age- and sex-matched controls.

CONCLUSIONS

Our data show elevated P-selectin levels in PXE patients potentially due to oxidative stress and elevated protease activity in PXE.

Clinical significance of serum levels of soluble intercellular adhesion molecule-1 and soluble L-selectin in malignant melanoma

Although several molecules have been evaluated as tumor markers of malignant melanoma (MM) progression, there are few available markers sensitive enough to detect recurrence or metastasis. The objective of the present study was to determine clinical significance of serum soluble adhesion molecules in the monitoring of progression in patients with MM. Serum levels of soluble L-selectin (sL-selectin), sE-selectin, sP-selectin, and soluble intercellular adhesion molecule-1 (sICAM-1) were determined by ELISA in 57 MM patients. In a retrospective longitudinal study, nine serum samples from two MM patients were analyzed during a follow-up period of 4.0 and 4.3 years, respectively. Serum sICAM-1 levels in MM patients were significantly higher than those in healthy controls and tended to be elevated as the disease stage progressed. In contrast, serum sL-selectin levels were significantly lower in MM patients compared to healthy controls and tended to decrease as the disease stage progressed. There was no significant difference in serum sE-selectin and sP-selectin levels between MM patients and normal control. In a longitudinal study, increased sICAM-1 and decreased sL-selectin levels were generally associated with the progression of MM. These results suggest that monitoring both sICAM-1 and sL-selectin is available to evaluate the progression of MM.

Neutrophil adhesion molecule expression in the developing neonatal rat exposed to hyperoxia

Neonatal rats have an increased tolerance to hyperoxia, which is associated with a diminished pulmonary inflammatory response compared with adults. To investigate this differing response, expression of the neutrophil adhesion molecules, L-selectin and CD18, and levels of soluble L-selectin, were examined using flow cytometry and sandwich enzyme-linked immunosorbent assay on air-exposed neonatal rat neutrophils at 0-24 and 72 h and 7, 10, 14, and 21 d of age compared with the adult and after exposure to hyperoxia (>/= 98% O2) for 56 h in adults and for 72 h and 7 d in neonates. Expression of L-selectin in 0-24-h neonates was similar to adults, but was significantly lower than adults at 72 h and 7 d (P = 0.011). Soluble L-selectin levels were significantly higher than those in adults in the 0-24- and 72-h neonates (P < 0.001). CD18 expression in unstimulated and activated neutrophils of neonatal rats was higher at 0-24 h than in the adult (P < 0.001), but thereafter did not differ from adults. After hyperoxic exposure, L-selectin did not differ between the exposure groups but soluble L-selectin tended to increase in neonates after 7 d of O2 exposure Finally, CD18 was significantly higher after hyperoxic exposure of the adult (P = 0.008), but did not change with oxygen exposure in the neonate. Based on these findings, we speculate that differences between neonatal and adult rats in expression of L-selectin may contribute to delayed oxygen toxicity in neonatal rats.

Markers of endothelial function in pediatric stem cell transplantation for acute leukemia

BACKGROUND

Endothelial cells and leukocytes intimately interact in inflammation and coagulation processes, so that dysregulation of their function may lead to both cellular damage and thrombosis, which may occur as complications of bone marrow transplantation (BMT). Partially conflicting evidence about endothelial markers and their relationships with clinical complications after BMT has been reported in the literature. Since almost all studies were carried out in adults, we evaluated some recent available markers of endothelial cell function in pediatric patients undergoing stem cell transplantation (SCT) for acute leukemia.

PROCEDURE

We studied the variation in circulating serum endothelial-selectin (ES), leukocyte-selectin (LS), thrombomodulin (TM), von Willebrand factor (vWF), nitrate + nitrite (NO(2) (-)/NO(3) (-)), endothelin-1 (EN), and tissue factor (TF) in 21 pediatric patients undergoing SCT for acute leukemia.

RESULTS

ES and LS significantly lowered following SCT and returned to pre-SCT levels 4 weeks after the procedure. NO(2) (-)/NO(3) (-) markedly increased following SCT. Also, TM and vWF increased, although such changes did not reach statistical significance. EN and TF did not appreciably change. A strong correlation was observed between white blood cell (WBC) count and both ES and LS, as well as between such selectins. TM significantly correlated with both selectins and NO(2) (-)/NO(3) (-). The pre-conditioning levels of TM and vWF in patients undergoing major complications, considered altogether, were significantly lower and higher, respectively, than in uncomplicated patients. NO(2) (-)/NO(3) (-) levels 3 and 4 weeks post-SCT were significantly lower in patients suffering from veno occlusive disease. Both selectins were significantly higher in allo- than in auto-transplanted patients 4 weeks after SCT.

CONCLUSIONS

Our data support the hypothesis of severe endothelial damage after conditioning and SCT, particularly allogeneic. However, the increase in TM, which has strong anticoagulant properties, and metabolites of NO, involved also in protective actions, may reflect regeneration of the anti-thrombotic endothelial function. This could take place after transitory functional impairment, rather than pure endothelial damage.

Soluble l-selectin (sCD62L) in relapsed childhood acute lymphoblastic leukaemia

Soluble l-selectin (sCD62L) plasma concentrations at diagnosis and outcome were investigated in 193 children at first relapse of acute lymphoblastic leukaemia (ALL) after treatment according to the Berlin-Frankfurt-Münster relapsed ALL multicentre trials, ALL-REZ BFM 95 and 96. sCD62L was low (< fifth paediatric reference percentile) in 63 (33%) and high (> 95th percentile) in 36 (19%) children, and was independent of remission duration, sex, BCR-ABL fusion or extramedullary disease. High sCD62L was associated with circulating blasts and T-cell phenotype. More initial adverse events occurred in children with high and low levels of sCD62L (23 out of 99) than in those with normal levels (9 out of 94, P = 0.018). Among 75 worst-prognosis patients (risk groups S3/S4, isolated bone marrow relapse occurring less than 6 months after elective cessation of front-line therapy, or T-cell phenotype with bone marrow involvement), 27 had low sCD62L and decreased event-free survival (EFS) probability (PEFS5 = 0.09 at 5 years) and duration (219 d) compared with normal sCD62L (29 out of 75, PEFS5 = 0.24, 640 d, P = 0.01). Low (44 out of 118), normal (72 out of 118), and high (19 out of 118) sCD62L non-S3/S4 patients fared similarly (average PEFS5 = 0.45, 1369 d; P = 0.5). Low sCD62L may be a marker of malignant blasts replacing normal sCD62L-producing haematopoietic cells. In children with first relapse of ALL and worst prognosis, plasma sCD62L may be useful for risk-adapted stratification.

Decreased expression levels of L-selectin on subsets of leucocytes and increased serum L-selectin in severe psoriasis

L-selectin is a leucocyte adhesion molecule involved in leucocyte interactions with vascular endothelial cells. Following leucocyte activation L-selectin is endoproteolytically released from the cell surface. To assess whether psoriasis vulgaris results in systemic leucocyte activation, we examined expression levels of L-selectin on subsets of peripheral blood leucocytes from patients with psoriasis (n = 25) and normal control subjects. Serum levels of soluble L-selectin were quantified by ELISA in patients with psoriasis (n = 75), pustulosis palmaris et plantaris, and contact dermatitis, as well as normal control subjects. Psoriasis severity was evaluated by psoriasis area and severity index (PASI). L-selectin expression levels on CD4+ T cells, B cells, monocytes, and neutrophils from patients with severe-type psoriasis (PASI > or = 15) was significantly decreased compared with leucocytes from normal control subjects. Furthermore, L-selectin expression on CD4+ T cells showed good inverse correlation with PASI scores. Monocyte L-selectin expression was restored when the skin lesions of psoriasis were remitted. The frequencies of L-selectin+ CD4+ T cells or L-selectin+ CD8+ T cells from patients with psoriasis were almost normal. Serum L-selectin levels in patients with severe-type psoriasis were significantly higher than those in normal control subjects. These results suggest that subsets of leucocytes may be activated in psoriasis, and that L-selectin expression levels on some leucocyte subsets, especially CD4+ T cells, tend to correlate with disease severity of psoriasis.

Circulating L-selectin concentrations in children with recent-onset IDDM

To clarify conflicting claims of altered serum concentrations of soluble L-selectin (sCD62L) in recent-onset IDDM, sCD62L was measured in 89 children and adolescents with IDDM (35 recent-onset, 12 during the first year of insulin treatment, and 42 with long-standing (> 1 yr) treatment) alongside 124 controls. Children < 14 yr of age both with and without IDDM (n = 160) had grossly elevated sCD62L concentrations (20.2 +/- 4.9 nmol/l), as compared with adolescents (14-18 yr, n = 23; 15.9 +/- 3.9 nmol/l) and adults (> 18 yr, n = 30; 11.2 +/- 2.3 nmol/l) (p < 0.0001). Multivariate analysis confirmed the strong inverse association between age and sCD62L (p < 0.001) while revealing that sCD62L concentrations were slightly elevated in recent-onset IDDM, as compared with insulin-treated IDDM patients or nondiabetic controls (p = 0.028). Actual sCD62L concentrations in the 35 recent-onset IDDM patients were 22.2 +/- 4.9 nmol/L vs 19.6 +/- 3.6 nmol/l in 35 non-diabetic controls matched for age (p = 0.022). While this significant but small rise of systemic sCD62L reflects leukocyte activation, it is obscured by the inverse association between sCD62L and chronological age in children and adolescents. Therefore, determining sCD62L serum concentrations appears to be of limited value for clinical investigators caring for children and adolescents with IDDM.

Expression and release of adhesion molecules by human acute myelogenous leukemia blasts

The expression and release of adhesion molecules by acute myelogenous leukemia (AML) blasts was investigated in vitro. For most patients AML blasts expressed relatively low levels of membrane-bound L-selectin and Intercellular adhesion molecule 1 (ICAM-1), but their soluble forms were detected in the supernatants for the majority of patients when AML blasts were cultured in vitro. These in vitro levels of SL-selectin and sICAM-1 were considerably lower than the normal serum levels. Divergent and relatively small alterations in SL-selectin and sICAM-1 levels were usually observed when exogenous growth factors were present during AML blast culture, whereas increased SL-selectin levels were observed after coculture of AML blasts and normal leucocytes. E- and P-selectin were neither expressed nor released by AML blasts. We conclude that AML blasts are a source of soluble adhesion molecules.

Circulating L-selectin levels and endothelial CD34 expression in inflammatory bowel disease

OBJECTIVE

Soluble L-selectin (sL-selectin) concentrations are positively correlated with disease activity in ulcerative colitis (UC) but not in Crohn's disease (CD). This difference in sL-selectin regulation could be due to a disease specific regulation of L-selectin ligands. The aim of this study was to compare levels of circulating sL-selectin, expression of the L-selectin ligand CD34 in the affected colon, and inflammatory bowel disease activity.

METHODS

Twenty-three patients with UC, 16 patients with CD, and 18 control subjects were included in the study. In blood samples concentrations of serum sL-selectin were determined by an ELISA technique. In colonoscopically obtained biopsies, CD34 expression was evaluated by immunohistochemical methods using monoclonal CD34 antibodies. Disease activity was determined by a clinical semiquantitative scale.

RESULTS

sL-selectin levels were found to be significantly increased along with increasing disease activity in UC (p < 0.001) but not in CD (p > 0.05) patients. UC patients with quiescent and severe disease activity had significantly lower (p < 0.005) and higher (p < 0.002) sL-selectin concentrations than controls, respectively. CD34 expression was found to be increased in both disease groups as compared with controls (p < 0.05).

CONCLUSION

A disease-specific regulation of CD34 was not found as an explanation for the distinction in sL-selectin regulation. In the light of recent reports on low sL-selectin in other diseases, it is suggested instead that ongoing neutrophil activation may be the reason for low sL-selectin concentrations during quiescent disease stages, whereas chemokine secretion could explain the increased levels of sL-selectin associated with severe disease activity.

Decreased soluble adhesion molecule L-selectin plasma concentrations after major trauma

BACKGROUND

Binding of the leukocyte glycoprotein L-selectin to ligands expressed by activated endothelium directs leukocyte recruitment to areas of acute inflammation. Sequestration by activated microvascular endothelium has been proposed to explain the low plasma concentrations of soluble L-selectin (sCD62L) observed early in patients with acute respiratory distress syndrome. We hypothesized that inflammatory endothelial activation may occur in trauma patients, leading to decreased sCD62L plasma concentrations.

METHODS

This study was a prospective analysis of sCD62L plasma concentrations in patients with isolated head injuries and multiple trauma patients without head injuries admitted to two tertiary-level intensive care units. sCD62L plasma concentrations were determined in 18 consecutive adult patients with isolated moderate and severe head injuries and in 13 multiple trauma patients without head injuries immediately upon admission to the intensive care unit and then daily for up to 10 days after trauma.

RESULTS

Compared with healthy adult controls (n=22), patient sCD62L plasma concentrations were significantly decreased upon admission (5.7+/-1.6 vs. 11.0+/-1.7 pmol/mL; p < 0.001). In all patients, sCD62L concentrations remained depressed throughout the study period. sCD62L concentrations did not differ significantly between patients with isolated head injuries and multiple trauma patients without head injuries, although repeated-measures analysis of variance showed significantly more depressed sCD62L concentrations associated with severe (n=14) compared with moderate head injuries (n=4) during the study period (p < 0.05).

CONCLUSION

Patients with major trauma present with a significant reduction of sCD62L plasma concentrations within the first 12 hours after trauma and during subsequent intensive care. This finding suggests widespread microvascular endothelial activation after trauma, which may be associated with increased neutrophil extravasation.

Kinetics of circulating selectin levels during bone marrow aplasia

We have studied the kinetics of plasma levels of circulating (c)selectins in 8 patients undergoing bone marrow or stem cell transplantation to gain estimates for the distribution and half-life of (c)selectins and to potentially identify an endothelial source of cP-selectin in patients who are deprived of platelets and megakaryocytes. Blood was sampled just before conditioning treatment and immediately after, at 2 occasions under bone marrow aplasia (1 and 2 wk after BMT), on 2 separate days (3-8 d apart) before and at 60 min after platelet transfusion, and 30-72 d after BMT. All (c)selectins showed a strikingly parallel decrease during bone marrow aplasia: cP-selectin decreased by a median of 70% (range: 59-95%), cE-selectin by 63% (range: 27-78%), and cL-selectin by 75% (range: 66-90%) compared to baseline (p=0.012 for all comparisons). Estimates for plasma half-lives of all (c)selectins were obtained from individual time vs. concentration profiles of the maximal decreases and ranged from 2 to 4 d. cP-selectin increased by 23% (p=0.003), cE-selectin by 5% (p=0.041) and cL-selectin by 19% (p=0.009) 1 h after the platelet transfusions. Based on these results the calculated volume of distribution (Vd) of transfused (c)selectins was 2.5-fold higher than the plasma volume, which supports the concept of the in-vivo expression of binding sites, i.e. ligands, for cE-selectin and cL-selectin. In summary, while our study cannot provide any evidence for endothelial cells as a source of cP-selectin, we have found for the first time evidence for the existence of ligands for soluble cE-selectin and cL-selectin in humans.

Soluble L-selectin concentration in bronchoalveolar lavage fluid obtained from infants who develop chronic lung disease of prematurity

AIMS

To explore the changes in neutrophil adhesion molecule expression and release into bronchoalveolar lavage fluid (BAL) obtained from infants who developed chronic lung disease (CLD).

METHODS

BAL fluid was obtained from 37 infants: 18 (median gestation 26 weeks, birthweight 835 g) who developed CLD, 12 (29 weeks, 1345 g) with respiratory distress syndrome (RDS) and seven control infants (33 weeks, 2190 g).

RESULTS

Soluble L-selectin (sL-selectin) in BAL fluid from the CLD and non-CLD groups was similar immediately after birth, but in infants who subsequently developed CLD, sL-selectin remained persistently increased (at day 7: CLD 42.6 vs RDS 6.0 ng/ml, p < 0.05; CLD vs controls 1.5 ng/ml; p < 0.05). CD11b/CD18 expression on neutrophils obtained by BAL increased with time to reach a maximum at 17 days of age in infants who developed CLD.

CONCLUSIONS

These results suggest that leucocyte traffic persists in infants who develop CLD and may have an important part to play in the pathogenesis of CLD.

L-selectin expression in CD34 positive cells in chronic myeloid leukemia

L-selectin is a cell adhesion molecule, expressed on leukocytes and involved in the regulation of leukocyte traffic. This adhesion receptor is implicated in hematopoiesis by the interaction of hematopoietic stem cells and progenitors to stroma in the bone marrow microenvironment. We found that L-selectin expression on CD34++ cells from patients with chronic myelogenous leukemia (CML) is decreased or deficient, reflecting one of the features of malignant CML progenitors. In this review, we briefly describe the structure and function of L-selectin, and its role in hematopoiesis and its expression in leukemia and lymphoma. Finally, we discuss the abnormal adhesiveness of CML progenitor cells, and the role of L-selectin in this defect.

Dexamethasone down-regulates the expression of L-selectin on the surface of neutrophils and lymphocytes in humans

OBJECTIVE

On the basis of previous animal studies, we hypothesized that dexamethasone may reduce the expression of L-selectin on neutrophils and lymphocytes in healthy men.

METHODS

A double-blind, randomized, placebo-controlled, and three-way crossover trial was conducted in nine healthy men. Every subject received four identical infusions of saline solution, 0.04 mg/kg dexamethasone, or 1.0 mg/kg dexamethasone during three observation periods of 48 hours each.

RESULTS

Dexamethasone time and dose dependently decreased the L-selectin expression on neutrophils and lymphocytes as measured by flowcytometry. This effect occurred with a time lag of 8 hours after start of treatment: the L-selectin binding index of neutrophils decreased by a maximum of -50% (confidence interval [CI], -37% to -63%) and that of lymphocytes by -26% (CI, -8% to -45%) at 32 hours after the start of treatment with high-dose dexamethasone (p < 0.016). Low-dose dexamethasone had only a transient effect on L-selectin expression of lymphocytes and a less pronounced effect on L-selectin expression of neutrophils.

CONCLUSION

Dexamethasone time and dose dependently decreases L-selectin expression on neutrophils and lymphocytes in health men, an effect that is less pronounced than that previously reported for animals.

Serum levels of adhesion molecules and cytokines in patients with acute leukaemia

The cytokine network and the adhesion molecule system are intercellular signal pathways. The cytokine effects are modulated in vivo by soluble cytokine antagonists, whereas the cell to cell contact mediated by adhesion molecules and their ligands may be blocked by the soluble forms of the adhesion molecules. The cytokine network is important for proliferation and cytokine secretion by acute leukaemia blasts, and membrane-bound adhesion molecules are important for blast interactions with neighbouring cells of the in vivo microenvironment. Both these signal systems are operative during the period of cytopenia following intensive chemotherapy for acute leukaemia. In the present review, we discuss the influence of disease status, chemotherapy and complicating infections on serum levels of cytokines and soluble adhesion molecules in acute leukaemia patients. We have demonstrated increased serum levels of both cytokines and cytokine antagonists in acute leukaemia patients with complicating bacterial infections during chemotherapy-induced cytopenia. Serum levels of the selectin adhesion molecules were decreased during bacterial infections in leukopenic patients compared to healthy individuals. In contrast, the intercellular adhesion molecule-1 response and the cytokine/cytokine antagonist responses were qualitatively similar to responses seen in previously healthy individuals with serious bacterial infections.

Soluble L-selectin in peripheral arterial disease: relationship with soluble E-selectin and soluble P-selectin

Soluble L-selectin, E-selectin and P-selectin were measured in a small case control study of 42 patients with peripheral arterial disease and 42 age and sex matched controls. Levels of soluble L-selectin were 1204 +/- 221 ng/ml (mean +/- S.D.) in the patients compared to 1256 +/- 271 ng/ml in the controls (P = 0.37). There was also no difference in levels of soluble E-selectin (57 +/- 17 ng/ml versus 51 +/- 20 ng/ml, P = 0.15) but levels of soluble P-selectin were increased (249 +/- 101 ng/ml versus 198 +/- 98 ng/ml, P = 0.011). There were no significant correlations between any of the selectins and the risk factors for atherosclerosis or with any leucocyte index. The data point to different mechanisms of release of the soluble selectins in peripheral atherosclerosis and may have important implications for leukocyte/endothelial cell interactions.

Cerebrospinal fluid soluble L-selectin (sCD62L) in meningoencephalitis

The leucocyte adhesion molecule L-selectin (CD62L) is rapidly cleaved off proteolytically after cell activation, generating soluble L-selectin (sCD62L) molecules. sCD62L concentrations were determined in 185 cerebrospinal fluid (CSF) samples obtained from children aged 1 month to 17 years. In 36 CSF samples of children with meningoencephalitis, sCD62L was significantly higher (median 209 fmol/ml) than in samples of children with other febrile diseases (n = 67, median 50 fmol/ml) or non-febrile disorders (n = 82, median 44 fmol/ml). There was a positive correlation between CSF protein and CSF sCD62L (rS = 0.68), suggesting that a disturbed blood-brain barrier contributes to raised sCD62L concentrations in the CSF. However, the CSF sCD62L/protein ratio of children with meningoencephalitis was significantly higher than in children with other febrile diseases or non-febrile disorders, indicating that sCD62L concentrations in children with meningoencephalitis were higher than expected from plasma leakage alone. It is concluded that both an impaired blood-brain barrier and the generation of sCD62L by infiltrating leucocytes contribute to raised CSF sCD62L concentrations in children with meningoencephalitis.

Diminished soluble and total cellular L-selectin in cord blood is associated with its impaired shedding from activated neutrophils

We have previously shown that surface levels of the adhesive glycoprotein, L-selectin, are diminished on cord blood neutrophils (polymorphonuclear leukocytes, PMN) and associated with impaired adherence to endothelium under flow conditions. To test the hypothesis that diminished surface levels reflect a total cellular deficiency, we measured L-selectin in PMN lysates and plasma from cord and adult blood. L-selectin content was decreased in cord blood PMN lysates compared with those of adults by both Western blot analyses and ELISA (cord blood, 1195 +/- 160 pg/mL; adult, 1870 +/- 260 pg/mL; X +/- SEM; p < 0.05). Soluble L-selectin levels were also decreased in cord blood plasma (324 +/- 24 ng/mL versus 537 +/- 28 ng/mLiter in adult plasma, p < 0.01). To evaluate L-selectin function, we next compared the dose dependent effect of several chemoattractants on shedding of L-selectin from cord blood and adult PMN. Adult PMN showed greater overall shedding of L-selectin as compared with cord blood PMN after stimulation with fMet-Leu-Phe (p < 0.03) and granulocyte-macrophage colony-stimulating factor (p < 0.02). In contrast, shedding of L-selectin was similar between groups after IL-8 tested stimulation. We conclude that cord blood PMN have a decreased cellular content of L-selectin in addition to an impaired ability to shed surface L-selectin in response to specific inflammatory mediators.