Expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in human crescentic glomerulonephritis

AIMS: In glomerulonephritis, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) may play important roles in the formation of crescents. These studies are designed to evaluate the expression patterns of ICAM-1 and VCAM-1 in human crescentic glomerulonephritis and to determine the cellular origin of adhesion molecules in the crescentic lesions. METHODS AND RESULTS: We examined the expression of ICAM-1 and VCAM-1 proteins in renal biopsies with cellular (n=7), fibrocellular (n=9) or fibrous (n=4) crescentic glomerulonephritis, and six controls by immunohistochemistry. mRNA expression of ICAM-1 and VCAM-1 was further evaluated by RNA in-situ hybridization. Cytokeratin or CD68 immunohistochemistry was performed on the same sections, where in-situ hybridization had been carried out. In cellular crescents, ICAM-1 and VCAM-1 proteins were over-expressed to a similar extent. Of the three types of crescents, the extent of ICAM-1 immunopositivity was the greatest in the cellular crescents and decreased towards the fibrous crescents (P < 0.05). Yet the extent of VCAM-1 immunoreactivity was not different between the types. Fibrous crescents still contained some epithelial cells and showed only VCAM-1 expression. In the glomeruli with cellular or fibrocellular crescents, the extent of ICAM-1 immunopositivity in the glomerular tufts was significantly larger than that of VCAM-1 (P < 0.05). In an in-situ hybridization study, the mRNA expression patterns of ICAM-1 and VCAM-1 paralleled their protein expressions. A double-labelling study showed that the signal for ICAM-1 and VCAM-1 mRNAs was mainly present in cytokeratin-positive and CD68-negative cells in the crescentic lesions. CONCLUSIONS: These results suggest that glomerular parietal epithelial cells in cellular crescents up-regulate both ICAM-1 and VCAM-1, and that some epithelial cells retained in fibrous crescents persistently over-express VCAM-1, but not ICAM-1. They also suggest that ICAM-1 is involved in early leucocyte recruitment into glomeruli in crescentic glomerulonephritis.     

Increased adhesion to vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 of eosinophils from patients with asthma

Adhesion of peripheral blood eosinophil and neutrophil granulocytes to the endothelial cell adherence receptors E-selectin, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 has been measured. The study included patients with allergic rhinitis, patients with mild allergic and nonallergic asthma, and healthy individuals; 10 persons were in each group. In addition, assay of eosinophil and neutrophil cell surface expression of the receptor complex CD11b/CD18 was performed. Increased eosinophil adhesion to vascular cell adhesion molecule-1 (p < 0.05) and intercellular adhesion molecule-1 (p < 0.05) was demonstrated in the patients with a more labile asthma, that is, a peak expiratory flow rate variability of more than 10%, suggesting a relationship to the degree of ongoing inflammation in the airways of the patients. The increased eosinophil adhesion was most probably due to a functional upregulation of the CD11b/CD18 and very late activation antigen-4 receptors, because the number of receptors measured as cell surface expression was unaltered. The increased eosinophil adhesion in the patients with high peak expiratory flow rate variability appeared independent of atopy. The increased adhesion was not entirely specific to the eosinophils, because neutrophils from patients with a peak expiratory flow rate variability of more than 10% also demonstrated increased adhesion to intercellular adhesion molecule-1 (p < 0.05) when compared with neutrophils from the patients with low peak expiratory flow rate variability. In conclusion, the demonstrated priming of eosinophil adhesion to vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 might be one contributing mechanism behind the selective accumulation of eosinophils in the lung tissue of patients with asthma. (J ALLERGY CLIN IMMUNOL 1995;96:941-50.)     

Soluble intercellular cell adhesion molecule-1 in lung cancer: A meta-analysis

BackgroundMany recent studies have investigated the prognostic, diagnostic, and progressive features of soluble intercellular cell adhesion molecule-1 (sICAM-1) in lung cancer patients, but the results remained inconsistent. This study aimed to explore the value of serum sICAM-1 in patients with lung cancer.MethodsA comprehensive systematic literature search in the Wanfang databases, china national knowledge infrastructure, Pubmed, and Embase was carried out update to June 15, 2019. The standard mean difference (SMD), hazard ratio (HR), and 95% confidence interval (95% CI) were applied to investigate the effect sizes.Results23 observational studies were included. According to our results, the serum sICAM-1 concentrations in patients with lung cancer were significantly higher than that in controls (healthy controls: SMD: 4.08, 95% CI: 3.14–5.02, P < 0.001; benign lung diseases controls : SMD: 1.48, 95% CI: 0.23–2.73,P = 0.02). Fortunately, a subgroup analysis was performed by language, treatment status, and lung cancer types, and the statistical results were similar. Serum sICAM-1 levels were markedly higher in stage III/IV than stage I/II (SMD: 1.96, 95% CI: 1.08−2.84, P < 0.001), Additionally, lung cancer patients with lymph node metastasis had a higher concentrations of serum sICAM-1(SMD: 1.83, 95% CI: 0.95−2.72, P < 0.001), as well as with distant metastasis (SMD: 0.86, 95% CI: 0.47−1.25, P < 0.001). Additionally, patients with higher sICAM-1 levels were related to a significantly poorer prognosis (progression free survival: HR: 1.16, 95% CI: 1.07–1.26, P < 0.001; overall survival: HR: 1.45, 95% CI: 1.17–1.79, P = 0.001).ConclusionsOur study suggested that serum sICAM-1 levels may act as a potential marker for diagnosing lung cancer and predicting its staging, and were negatively correlated with prognosis of lung cancer.     

Effects of different hyaluronic acid products on synovial fluid levels of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in knee osteoarthritis

The aim of this study was to evaluate the effects of different hyaluronic acid (HA) forms on synovial fluid levels of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) during the treatment of patients with knee osteoarthritis (OA). Forty patients were randomly assigned to 2 groups that were treated with native sodium hyaluronate (group I) or cross-linked hylan G-F 20 (group II). Clinical evaluations and synovial fluid aspirations were performed before the 1st injection (baseline), the 2nd injection (week 1), the 3rd injection (week 2), and at 1 week after the 3rd injection (week 3). Synovial fluid levels of both ICAM-1 and VCAM-1 were significantly reduced at weeks 1 to 3, compared to the baseline values. The Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index was used for clinical evaluations; the WOMAC pain score and physical function score were progressively improved at weeks 1 to 3 in both groups; the WOMAC stiffness score was significantly improved at week 3 in both groups. No significant differences were noted between the 2 treatment groups in respect to ICAM-1 levels, VCAM-1 levels, WOMAC pain score, stiffness score, or physical function score at any time. The decreased ICAM-1 and VCAM-1 levels after intra-articular HA injection may help to explain the anti-inflammatory effects of HA therapy in knee OA.     

细胞粘附分子在狼疮性肾炎及膜增殖性肾炎肾组织中的表达

用免疫组化方法和计算机图像分析系统，对２５例狼疮性肾炎（ＬＮ）ＩＶ型及１５例膜增殖性肾炎（ＭＰＧＮ）Ｉ型患者肾组织内ＩＣＡＭ－１和ＶＣＡＭ－１的表达进行了定量研究。结果显示：ＭＰＧＮ及ＬＮ患者肾组织中ＩＣＡＭ－１及ＶＣＡＭ－１表达均显著增加，ＬＮ患者ＩｃＡＭ－１在肾小球内皮细胞表达最强，且与内皮细胞增殖程度显著正相关。     

Hypothermic preservation of lung allograft inhibits cytokine-induced chemoattractant-1, endothelial leucocyte adhesion molecule, vascular cell adhesion molecule-1 and intracellular adhesion molecule-1 expression

Organ dysfunction is a major clinical problem after lung transplantation. Prolonged cold ischaemia and reperfusion injury are believed to play a central role in this complication. The influence of cold preservation on subsequent warm reperfusion was studied in an isolated, ventilated and perfused rat lung. Rat lungs were flushed with cold Perfadex-solution and stored at 4 degrees C for different time periods. Thereafter lungs were perfused and ventilated for up to 3 h. Physiological parameters, production of inflammatory mediators and leucocyte infiltration were measured before and after perfusion. Lungs subjected to a cold ischaemia time of up to 6 h showed stable physiological conditions when perfused for 3 h. However, cold-ischaemia time beyond 6 h resulted in profound tissue oedema, thereby impairing ventilation and perfusion. Warm reperfusion and ventilation per se induced a strong inflammatory response, as demonstrated by a significant up-regulation of chemokines and adhesion molecules (cytokine-induced chemoattractant-1, intracellular adhesion molecule and endothelial leucocyte adhesion molecule), accompanied by enhanced leucocyte infiltration. Although the up-regulation of inflammatory mediators was blunted in lungs that were subjected to cold ischaemia, this did not influence leucocyte infiltration. In fact, cold ischaemia time correlated with leucocyte sequestration. Although cold preservation inhibits the expression of inflammatory mediators it does not affect leucocyte sequestration during warm reperfusion. Cold preservation might cause impairment of the endothelial barrier function, as evidenced by tissue oedema and profound leucocyte infiltration.     

Interferon-gamma up-regulates intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 and recruits lymphocytes into the vagina of immune mice challenged with herpes simplex virus-2

Lymphocyte recruitment into tissues involves interactions between adhesion molecules on vascular endothelial cells and corresponding ligands on the lymphocyte surface. In the present study we investigated the expression of four endothelial addressins in the vagina and their possible up-regulation by interferon-gamma (IFN-gamma) in immune mice after vaginal challenge with herpes simplex virus type 2. The adhesion molecules intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were minimally expressed in the vagina of non-immune mice with or without vaginal challenge and in immune mice before challenge, but both were up-regulated by IFN-gamma, directly or indirectly, in immune mice after challenge. Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) was detected in most vaginas but was not up-regulated by IFN-gamma in immune mice after virus challenge. E-selectin was not detected in any vaginas. The results suggest that ICAM-1 and VCAM-1 may be involved in rapid, IFN-gamma-mediated recruitment of lymphocytes to the vaginal mucosal of immune mice after local virus challenge.     

Serum levels of soluble intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and interleukin-2 receptor in patients with vernal keratoconjunctivitis and allergic conjunctivitis

BACKGROUND: Vernal keratoconjunctivitis (VKC) is characterized by severe ocular allergic inflammation that may have a poor visual prognosis. Due to the high frequency of the presence of atopic dermatitis (AD) in VKC, most systemic parameters are dependent on the clinical severity of AD. METHODS: Serum levels of sICAM-1, sVCAM-1, and sIL-2R were measured by enzyme-linked immunoassay using samples from 30 VKC patients, 30 allergic conjunctivitis (AC) patients, and 20 normal subjects, to determine whether the concentrations of these molecules are elevated. RESULTS: Circulating sICAM-1 and sIL-2R levels were increased in patients with VKC with AD compared with those in VKC without AD, AC, and normal controls. Serum levels of sVCAM-1 in VKC patients with and without AD were significantly higher than those in controls. No significant difference was found in the levels of sVCAM-1 between patients with VKC with and without AD. In VKC patients with AD, the sIL-2R level correlated significantly with severity of AD, whereas no such correlation was found for sICAM-1 and sVCAM-1. CONCLUSIONS: These results suggest that serum sVCAM-1 can be used as a marker to differentiate VKC from nonproliferative ocular allergic diseases, and specific immunologic features of VKC may underlie the upregulation of serum sVCAM-1.     

Lack of stimulatory effect of dienogest on the expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 by endothelial cell as compared with other synthetic progestins

Objectives: Monocyte adhesion to endothelial cells is an important initial event at the onset of atherosclerosis. It is partially mediated by the expression of adhesion molecules on the endothelial cell surface. While estrogens inhibit the development of atherosclerosis, the effect of co-administered progestin remains controversial. We examined the effect of progestins on cytokine-stimulated human umbilical venous endothelial cell (HUVEC) expression of adhesion molecules. Methods: In HUVECs, mRNA expression of progesterone receptors (PRs) and androgen receptors (AR) was determined by RT-PCR. HUVECs were stimulated by interleukin-1β (IL-1β) for 24 h with or without various steroids, and then the cell-surface expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was semiquantified by ELISA. Results: In all preparations of HUVECs used in this study, RT-PCR confirmed mRNA expression of both isoforms of PR, PR-A and PR-B, as well as AR. Addition of progesterone (10⁻¹⁰–10⁻⁷ M) or dienogest (DNG) (10⁻¹⁰–10⁻⁸ M) did not affect IL-1β-stimulated ICAM-1 or VCAM-1 expression. In contrast, medroxyprogesterone acetate, norethindrone acetate and levonorgestrel (10⁻¹⁰–10⁻⁸ M) dose-dependently increased cell adhesion molecules. The progestin-induced increase was blocked by the concomitant addition of mifepristone, a PR antagonist, but not by hydroxyflutamide, an AR antagonist, indicating that the progestin stimulation was mediated predominantly via PR. Conclusions: These results suggest that DNG, unlike other synthetic progestins, lacks stimulation of cell adhesion molecules. For the prevention of atherosclerosis, estrogen in combination with DNG may be a suitable regimen in hormone replacement therapy in postmenopausal women.     

Intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 cooperatively contribute to the cutaneous Arthus reaction

Immune complex (IC)-induced inflammation is mediated by inflammatory cell infiltration, a process that is highly regulated by expression of multiple adhesion molecules. The roles and interactions of ICAM-1 and VCAM-1, the major regulators of leukocyte firm adhesion, were examined in the cutaneous reverse-passive Arthus reaction using ICAM-1-deficient (ICAM-1-/-) mice and blocking mAb against VCAM-1. Within 8 h, IC challenge of wild-type mice induced edema, hemorrhage, interstitial accumulation of neutrophils and mast cells, as well as production of TNF-alpha and IL-6. All of these inflammatory parameters were reduced significantly in ICAM-1-/- mice. The blockade of VCAM-1 in wild-type mice did not affect any inflammatory parameters. In contrast, ICAM-1-/- mice treated with anti-VCAM-1 mAb had significantly reduced edema, hemorrhage, and neutrophil infiltration. Furthermore, VCAM-1 blockade in ICAM-1-/- mice suppressed cutaneous TNF-alpha and IL-6 production. Thus, VCAM-1 plays a complementary role to ICAM-1 in the cutaneous Arthus reaction by regulating leukocyte accumulation and proinflammatory cytokine production.     

Normal levels of soluble E-selectin, soluble intercellular adhesion molecule-1 (sICAM-1), and soluble vascular cell adhesion molecule-1 (sVCAM-1) decrease with age

sE-selectin, sICAM-1, sVCAM-1 and von Willebrand factor (vWF) were assayed in 238 samples in a longitudinal study of 81 normal children from 9.5 to 15.5 years old. Multilevel modelling was used to quantify changes with age. sE-selectin, sICAM-1 and sVCAM-1 all fell significantly over the age range (by 17%, 16%, and 10%, respectively). In contrast, levels of vWF were not age-dependent. Our findings highlight the need for age-matched controls when studying cell surface adhesion molecules in disease groups, and may imply developmental changes in expression of these molecules and their shedding from the cell surface.     

Smoke and C5a induce airway epithelial intercellular adhesion molecule-1 and cell adhesion

The human bronchial epithelial cell is one of the first cell types to be exposed to the irritants and toxins present in inhaled cigarette smoke. The ability of the bronchial epithelium to modulate inflammatory and immune events in response to cigarette smoke is important in the pathogenesis of smoke-induced airway injury. We have shown that cigarette smoke extract and the complement anaphylatoxin C5a both independently induce increased expression of intercellular adhesion molecule (ICAM)-1 on airway epithelial monolayers compared with unstimulated cells in vitro. This enhanced ICAM-1 expression is associated with a greater capacity of the airway epithelial cells to bind mononuclear cells, a process that appears to require the proinflammatory cytokine tumor necrosis factor-alpha and protein kinase C intracellular signaling. Exposure of epithelial monolayers to the combination of cigarette smoke followed by C5a results in an additive response for ICAM-1 expression and mononuclear cell adhesion compared with smoke or C5a challenge alone. Inhibiting C5a receptor expression can attenuate these responses. These findings suggest that smoke exposure in some way enhances the functional responsiveness of the C5a receptor expressed on these airway epithelial cells for subsequent C5a-mediated increases in ICAM-1 expression and mononuclear cell adhesion. Our results may help explain the initiation and propagation of inflammatory events in vivo induced by chronic airway exposure to cigarette smoke.     

ICAM-1与支气管哮喘的研究进展

细胞间粘附分子-1(intercellularadhesionmolecule-1,ICAM-1)是免疫球蛋白(immunoglobulin,Ig)超家族成员之一,对白细胞牢固黏附和白细胞从血管中迁移到炎症组织部位起着关键作用.白细胞表面粘附分子与血管内皮细胞表面的粘附分子(如:ICAM-1)相互作用后可介导白细胞从血液循环中迁移到肺组织的炎症部位,这在支气管哮喘发病机制中起着重作用.本综述将简阐述ICAM-1及其表达调控在支气管哮喘中的研究进展.     

血管内皮生长因子、细胞间黏附分子1在糖尿病大鼠肾小球的表达

目的 探讨血管内皮生长因子(VEGF)和细胞间黏附分子1(1CAM-1)在糖尿病肾病(DN)发生机理中的作用。方法 采用链脲佐菌素(STZ)诱发糖尿病(DM)大鼠模型，观察大鼠肾小球肥大、肾功能和24h尿蛋白改变以及用免疫组织化学和计算机图像分析技术定位、半定量检测VEGF和ICAM—1在DM大鼠肾小球的表达。结果 VEGF和ICAM—1在糖尿病大鼠肾小球中均有不同程度表达，VEGF主要分布于肾小球脏层上皮细胞的脑浆之中，ICAM—1主要分布于肾小球内皮细胞和系膜细胞的脑浆中。VEGF、ICAM-1水平与蛋白尿和肾小球肥大呈正相关关系。结论 DM大鼠肾小球VEGF和ICAM-1的升高可能参与了DN的疾病发展过程，估计是糖尿病肾病发生机理之一。     

细胞间黏附分子-1与血管生成的研究进展

实体肿瘤的生长、浸润和转移均依赖于血管生成这一进程,而血管生成是在一系列生长因子调控下实现的。有资料显示,细胞间黏附分子-1与血管生成有关,它通过与内皮细胞表面上的特异性受体结合而发挥其生物学活性,在某些疾病过程中的血管生成及发生发展过程中起着重要作用。现就细胞间黏附分子-1的生物学特性及与血管生成的关系研究进展概述如下。     

Eosinophils adhere to vascular cell adhesion molecule-1 via podosomes

Vascular cell adhesion molecule (VCAM)-1 supports specific eosinophil adhesion via alpha4beta1 integrin. We tested the hypothesis that adhesive contacts formed by eosinophils on VCAM-1 are different from focal adhesions formed by adherent fibroblasts. Eosinophils adherent on VCAM-1 formed punctate adhesions that fit the criteria for podosomes, highly dynamic structures found in adherent transformed fibroblasts, osteoclasts, and macrophages. The structures contained beta1 integrin subunit, phosphotyrosine-containing proteins, punctate filamentous actin, and gelsolin, a podosome marker. In contrast, nontransformed fibroblasts on VCAM-1 formed peripheral focal adhesions that were positive for alpha4, beta1, phosphotyrosine, vinculin, talin, and paxillin; negative for gelsolin; and associated with microfilaments. Phorbol myristate acetate or tumor necrosis factor-alpha and interleukin-5 stimulated podosome formation in adherent eosinophils. Because podosomes in tumor cells are associated with extracellular matrix degradation, we analyzed the VCAM-1 layer. VCAM-1 was lost under adherent eosinophils but not under adherent fibroblasts. This loss was inhibited by the metalloproteinase inhibitor ortho-phenanthroline and correlated with expression and podosome localization of a membrane-tethered metalloproteinase, a disintegrin and metalloproteinase domain 8. Podosome-mediated VCAM-1 clearance may be a mechanism to regulate eosinophil arrest and extravasation in allergic conditions such as asthma.     

The role of amniotic fluid interleukin-6, and cell adhesion molecules, intercellular adhesion molecule-1 and leukocyte adhesion molecule-1, in intra-amniotic infection

PROBLEM: To determine amniotic fluid concentrations and correlations of interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1), and leukocyte adhesion molecule-1 (LAM-1) in patients with and without intra-amniotic infection. METHOD OF STUDY: Fourteen specimens with intra-amniotic infection and 45 without intra-amniotic infection were studied. Intra-amniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid IL-6, ICAM-1, and LAM-1 levels were determined by an enzyme-linked immunoassay, and normalized by amniotic fluid creatinine levels. RESULTS: Amniotic fluid concentrations of IL-6 and LAM-1 were significantly higher in patients with than without intra-amniotic infection. However, amniotic fluid ICAM-1 concentrations were not significantly different between two groups. Amniotic fluid IL-6, LAM-1, and ICAM-1 were positively correlated. CONCLUSIONS: Our data indicate that amniotic fluid IL-6 is significantly associated with an increased adhesion molecule expression in intra-amniotic infection. However, LAM-1 plays a more important role than ICAM-1 in intra-amniotic infection.     

Levels of intracellular adhesion molecule-1 and vascular cell adhesion molecule-1 in children with Henoch-Sch?nlein purpura.

BACKGROUND AND PURPOSE: Henoch-Sch?nlein purpura (HSP) is a small vessel vasculitis. Soluble adhesion molecules play a very important role in the immuno-inflammatory reaction of damaged vascular tissues. This study investigated the prognostic and diagnostic potential of soluble intracellular adhesion molecule-1 (sICAM-1) and vascular cell adhesion molecule-1 (sVCAM-1) in HSP. METHODS: Serum levels of sICAM-1 and sVCAM-1 were studied in 26 children with HSP. Paired blood samples (during acute and convalescent stages) were collected from 17 of the children and assayed by enzyme-linked immunosorbent assay. Correlations with clinical manifestations were examined. Seventeen healthy children served as controls. RESULTS: Both sICAM-1 and sVCAM-1 were significantly elevated at the acute stage compared with the remission stage of HSP patients versus controls (p=0.006 and p=0.0173, respectively). CONCLUSIONS: Although the levels of sICAM-1 and sVCAM-1 were not correlated with the severity of clinical manifestations in HSP, these soluble adhesion molecules may serve as diagnostic markers.     

细胞间黏附分子-1的研究概况及临床意义

细胞间黏附分子-1( ICAM-1)是一种细胞表面的跨膜糖蛋白,可介导细胞与细胞间或细胞与细胞外基质之间的相互作用.ICAM-1广泛地参与细胞黏附、炎症的发生发展、信号转导和肿瘤转移等多种重要的生理及病理过程.在临床上,ICAM-1可作为多种炎症或肿瘤发展和预后的重要生物标记物之一.以ICAM-1为靶点的药物或能预防和治疗多种急、慢性炎症引起的组织损伤和肿瘤等.     

Differential up-regulation of circulating soluble and endothelial cell intercellular adhesion molecule-1 in mice.

Although circulating levels of soluble intercellular adhesion molecule-1 (sICAM-1) are frequently used as an indicator of the severity of different immune, inflammatory, or neoplastic diseases, little is known about the factors that govern plasma sICAM-1 concentration and its relationship to the membranous form of ICAM-1 (mICAM-1) expressed on vascular endothelial cells. Plasma sICAM-1 concentration (measured by enzyme-linked immunosorbent assay) and mICAM-1 expression (measured using the dual radiolabeled monoclonal antibody technique) in different vascular beds (eg, lung, small intestine, and spleen) were monitored in wild-type (C57BL) and ICAM-1-deficient mice, before and after administration of tumor necrosis factor (TNF)-alpha. In wild-type mice, TNF-alpha elicited time-dependent increases in lung and intestine mICAM-1 (plateau achieved at 12 hours), with a corresponding increase in plasma sICAM-1 (peaked at 5 hours and then declined). The initial increases in mICAM-1 and pulmonary leukocyte sequestration (measured as lung myeloperoxidase activity) induced by TNF-alpha preceded any detectable elevation in sICAM-1. In ICAM-1-deficient mice, plasma sICAM-1 was reduced by approximately 70%, with > 95% reductions of mICAM-1 in lung and intestine, and > 75% reduction in splenic accumulation of anti-ICAM-1 antibody. Although TNF-alpha doubled plasma sICAM-1 in ICAM-1-deficient mice, mICAM-1 was unaffected in all tissues. Either splenectomy or pretreatment with cycloheximide resulted in an attenuated TNF-induced increase in sICAM-1, without affecting mICAM-1 expression. These findings indicate that plasma sICAM-1 concentration does not accurately reflect the level of ICAM-1 expression on endothelial cells in different vascular beds.