Endothelial cell activation in vasculitis of peripheral nerve and skeletal muscle

Machine learning for early detection and severity classification in people with Parkinson's disease

Early detection of Parkinson's disease (PD) and accurate assessment of disease progression are critical for optimizing treatment and rehabilitation. However, there is no consensus on how to effectively detect early-stage PD and classify motor symptom severity using gait analysis. This study evaluated the accuracy of machine learning models in classifying early and moderate-stages of PD based on spatiotemporal gait features at different walking speeds. A total of 178 participants were recruited, including 103 individuals with PD (61 early-stage, 42 moderate-stage) and 75 healthy controls. Participants performed a walking test on a 24-m walkway at three speeds: preferred walking speed (PWS), 20% faster (HWS), and 20% slower (LWS). Key features-walking speed at PWS, stride length at HWS, and the coefficient of variation (CV) of the stride length at LWS-achieved a classification accuracy of 78.1% using the random forest algorithm. For early PD detection, the stride length at HWS and CV of the stride length at LWS provided an accuracy of 67.3% with Naïve Bayes. Walking at PWS was the most critical feature for distinguishing early from moderate PD, with an accuracy of 69.8%. These findings suggest that assessing gait over consecutive steps under different speed conditions may improve the early detection and severity assessment of individuals with PD.

Diagnostic accuracy of dual-phase 18F-FP-CIT PET imaging for detection and differential diagnosis of Parkinsonism

Delayed phase 18F-FP-CIT PET (dCIT) can assess the striatal dopamine transporter binding to detect degenerative parkinsonism (DP). Early phase 18F-FP-CIT (eCIT) can assess the regional brain activity for differential diagnosis among parkinsonism similar with 18F-FDG PET. We evaluated the diagnostic performance of dual phase 18F-FP-CIT PET (dual CIT) and 18F-FDG PET compared with clinical diagnosis in 141 subjects [36 with idiopathic Parkinson's disease (IPD), 77 with multiple system atrophy (MSA), 18 with progressive supranuclear palsy (PSP), and 10 with non-DP)]. Visual assessment of eCIT, dCIT, dual CIT, 18F-FDG and 18F-FDG PET with dCIT was in agreement with the clinical diagnosis in 61.7%, 69.5%, 95.7%, 81.6%, and 97.2% of cases, respectively. ECIT showed about 90% concordance with non-DP and MSA, and 8.3% and 27.8% with IPD and PSP, respectively. DCIT showed ≥ 88% concordance with non-DP, IPD, and PSP, and 49.4% concordance with MSA. Dual CIT showed ≥ 90% concordance in all groups. 18F-FDG PET showed ≥ 90% concordance with non-DP, MSA, and PSP, but only 33.3% concordance with IPD. The combination of 18F-FDG and dCIT yielded ≥ 90% concordance in all groups. Dual CIT may represent a powerful alternative to the combination of 18F-FDG PET and dCIT for differential diagnosis of parkinsonian disorders.

Primary and secondary vasculitic neuropathy

Necrotizing vasculitis occurs as a primary phenomenon in connective tissue disorders and cognate fields, including polyarteritis nodosa and the Churg and Strauss syndrome variant, rheumatoid arthritis, systemic lupus and Wegener's granulomatosis. In all these conditions focal and multifocal neuropathy occur as a consequence of destruction of the arterial wall and occlusion of the lumen of small epineurial arteries. Vasculitis may also complicate the course of other conditions ranging from infection with the HIV and with the B and C hepatitis viruses to diabetes and sarcoidosis. Pathologically polymorphonuclear cells are present in the infiltrates of the vessel wall in primary necrotizing vasculitis, while in secondary vasculitis the inflammatory infiltrate is mainly composed of mononuclear cells. In all instances symptomatic vasculitis requires corticosteroid to control the inflammatory process and prevent further ischemic nerve lesions.

Advances in understanding and treatment of immune-mediated disorders of the peripheral nervous system

During recent years, novel insights in basic immunology and advances in biotechnology have contributed to an increased understanding of the pathogenetic mechanisms of immune-mediated disorders of the peripheral nervous system. This increased knowledge has an impact on the management of patients with this class of disorders. Current advances are outlined and their implication for therapeutic approaches addressed. As a prototypic immune-mediated neuropathy, special emphasis is placed on the pathogenesis and treatment of the Guillain-Barré syndrome and its variants. Moreover, neuropathies of the chronic inflammatory demyelinating, multifocal motor, and nonsystemic vasculitic types are discussed. This review summarizes recent progress with currently available therapies and--on the basis of present immunopathogenetic concepts--outlines future treatment strategies.

Enhanced expression of E-selectin on the vascular endothelium of peripheral nerve in critically ill patients with neuromuscular disorders

Neuropathic complication often occurs in critically ill patients, and changes in the microcirculation of the peripheral nerve have been suggested to play a role in the pathogenesis of the nerve lesion. We report the results of a pathological and immunohistochemical study of superficial peroneal nerve biopsy specimens in a series of 22 critically ill patients with sepsis and neuromuscular disorders. Eight patients had histopathological features of axonal neuropathy compatible with critical illness polyneuropathy (CIP). The nerve lesions ranged in severity from mildly reduced myelin-fiber density with sporadic axonal degeneration to marked fiber loss with abundant degenerative changes. In no patient did we detect evidence of primary demyelinization or inflammatory infiltrates. We analyzed the immunohistochemical expression of E-selectin, vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and tumor necrosis factor alpha (TNF-alpha) in nerve microvessels. Expression of E-selectin was significantly increased in endothelium of epineurial and endoneurial vessels, suggesting endothelial cell activation. These findings again confirm axonal degeneration as the major pathological feature of CIP. Our immunohistochemical data provide first evidence that activation of the endothelial cells of the microvessels in the endoneurium of human peripheral nerve does occur during sepsis. This specific activation might have implications with the mechanisms responsible for the axonopathy in critically ill patients.

The expression of adhesion molecules in muscle biopsies: the LFA-1/VLA-4 ratio in polymyositis

OBJECTIVES

The expression of three pairs of adhesion receptors and ligands was examined in 22 consecutive muscle biopsies showing morphological signs of inflammation.

MATERIAL AND METHODS

The following groups were studied: patients with polymyositis (PM) (n=7), patients with myositis that did not fulfil criteria for PM, i.e. suspected PM (n=5), patients with other diseases, with no clinical signs of inflammatory myopathy (n=6), and a small group of non-PM inflammatory myopathies (n=4). The endothelial expression of ICAM-1, VCAM-1 and E-selectin was evaluated, as was the cellular expression of LFA-1, VLA-4 and SLex. In addition, the expression of MHC class I and II was studied.

RESULTS

The ratio between the number of cells expressing LFA-1 and VLA-4 showed significant differences between the groups, with the lowest values in PM.

CONCLUSION

The LFA-1/VLA-4 ratio should be suitable for diagnostic purposes. Our findings also indicate that the VLA-4/VCAM-1 system is important for chronic T cell inflammation in muscle, in line with findings in other "hidden" organs like joints and the central nervous system.

Endothelial cell activation following moderate traumatic brain injury

Traumatic brain injury (TBI) initiates a cascade of acute and chronic injury responses which include disturbances in the cerebrovasculature that may result in the activation of the microvascular endothelial development of a dysfunction endothelium. The present study examines endothelial cell (EC) activation in a percussion model of moderate TBI. The criteria for endothelial activation used in these studies was surface expression of a number of markers collectively termed endothelial activation antigens. Temporal induction of the major histocompatibility (MHC) class II molecules, E-selectin (CD62E), vascular cell adhesion molecule (VACM-1) (CD106) as well as altered expression of constitutively expressed intercellular adhesion molecule-1 (ICAM-1) (CD54), the glucose transporter protein (glut-1), the transferrin receptor (tfR) (CD71), and MHC class I molecules was examined at various times following impact. Induction of E-selectin and increased expression of ICAM-1 was seen by 2 h post-impact (PI) and was sustained through 24 h PI. Decreased expression of immunologically reactive glut-1 and tfR was observed by 2-4 h PI and remained low up to 24 h PI. No induction of VCAM-1, MHC class II molecules or altered constitutive expression or MHC class I molecules was seen. Changes in EC activation were observed predominantly at the site of impact and were diminished temporarily. These results indicate that mild concussive injury to the brain results in activation of the endothelium.

Cell adhesion molecules in the development of inflammatory infiltrates in giant cell arteritis: inflammation-induced angiogenesis as the preferential site of leukocyte-endothelial cell interactions

OBJECTIVE

To investigate the expression pattern of adhesion molecules involved in leukocyte-endothelial cell interactions in giant cell arteritis (GCA).

METHODS

Immunohistochemical analysis was performed on frozen temporal artery sections from 32 patients with biopsy-proven GCA and from 12 control patients with other diseases. Adhesion molecules identified were intercellular adhesion molecule 1 (ICAM-1), ICAM-2, ICAM-3, vascular cell adhesion molecule 1 (VCAM-1), platelet endothelial cell adhesion molecule 1 (PECAM-1), E-selectin, P-selectin, L-selectin, lymphocyte function-associated antigen 1 (LFA-1), very late activation antigen 4 (VLA-4), Mac-1 (CD18/CD11b), and gp 150,95 (CD18/CD11c). Clinical and biochemical parameters of inflammation in the patients, as well as the duration of previous corticosteroid treatment, were prospectively recorded.

RESULTS

Constitutive (PECAM-1, ICAM-1, ICAM-2, and P-selectin) and inducible (E-selectin and VCAM-1) endothelial adhesion molecules for leukocytes were mainly expressed by adventitial microvessels and neovessels within inflammatory infiltrates. Concurrent analysis of leukocyte receptors indicated a preferential use of VLA-4/VCAM-1 and LFA-1/ICAM-1 at the adventitia and Mac-1/ICAM-1 at the intima-media junction. The intensity of inducible endothelial adhesion molecule expression (E-selectin and VCAM-1) correlated with the intensity of the systemic inflammatory response. Previous corticosteroid treatment reduced, but did not completely abrogate, the expression of the inducible endothelial adhesion molecules E-selectin and VCAM-1.

CONCLUSION

Inflammation-induced angiogenesis is the main site of leukocyte-endothelial cell interactions leading to the development of inflammatory infiltrates in GCA. The distribution of leukocyte-endothelial cell ligand pairs suggests a heterogeneity in leukocyte-endothelial cell interactions used by different functional cell subsets at distinct areas of the temporal artery.

Mechanisms of immune regulation in the peripheral nervous system

The peripheral nervous system (PNS) is a target for heterogenous immune attacks mediated by different components of the systemic immune compartment. T cells, B cells, and macrophages can interact with endogenous, partially immune-competent glial cells and contribute to local inflammation. Cellular and humoral immune functions of Schwann cells have been well characterized in vitro. In addition, the interaction of the humoral and cellular immune system with the cellular and extracellular components in the PNS may determine the extent of tissue inflammation and repair processes such as remyelination and neuronal outgrowth. The animal model experimental autoimmune neuritis (EAN) allows direct monitoring of these immune responses in vivo. In EAN contributions to regulate autoimmunity in the PNS are made by adhesion molecules and by cytokines that orchestrate cellular interactions. The PNS has a significant potential to eliminate T cell inflammation via apoptosis, which is almost lacking in other tissues such as muscle and skin. In vitro experiments suggest different scenarios how specific cellular and humoral elements in the PNS may sensitize autoreactive T cells for apoptosis in vivo. Interestingly several conventional and novel immunotherapeutic approaches like glucocorticosteroids and high-dose antigen therapy induce T cell apoptosis in situ in EAN. A better understanding of immune regulation and its failure in the PNS may help to develop improved, more specific immunotherapies.

Sialyl Lewis X, Lewis X, and N-acetyllactosamine expression on normal and glaucomatous eyes

PURPOSE

Sialyl Lewis X (sLex), Lewis X (Lex), and N-acetyllactosamine are carbohydrate chains of neolactoglycoconjugates which are expressed by specific cell types and are important in the functioning of cells within an organism. This study attempts to determine the expression of these glycoconjugates on the conjunctiva, cornea, and trabecular meshwork (TM) of both normal and glaucomatous eyes.

METHODS

Frozen anterior segment sections of both normal and glaucomatous human cadaver eyes, as well as rabbit eyes, were stained with a panel of monoclonal antibodies (mAbs) to neolactoglycoconjugates using an Avidin Biotin Peroxidase Complex/Alkaline Phosphatase staining method.

RESULTS

SLex characteristically stained both human conjunctival and corneal epithelia in normal (n=5) and glaucomatous (n=5) sections. SLex stained corneal and conjunctival epithelia of glaucomatous eyes much more intensely than normal eyes. Rabbit cornea sections stained for sLex, Lex, and N-acetyllactosamine. However, human cornea only consistently stained with sLex. Normal and glaucomatous human TM sections did not stain for sLex, Lex, or N-acetyllactosamine.

CONCLUSIONS

The expression of glycoconjugates with sLex side chains appears to be upregulated in the conjunctival and corneal epithelia of glaucomatous eyes. Distinct species specific differences were noted in Lex and N-acetyllactosamine staining patterns in rabbit and human corneal epithelia.

Increased levels of soluble forms of adhesion molecules in Takayasu arteritis

The present series of experiments were designed to determine if soluble forms of vascular cell adhesion molecule-1 and inter cellular adhesion molecule-1 are elevated in the setting of Takayasu arteritis. Plasma levels of these soluble adhesion molecules were measured by enzyme-linked immunosorbent assay in 73 Takayasu arteritis and 36 age-matched normal controls and examined with respect to the age of patients. Soluble vascular cell adhesion molecule-1 levels were significantly higher in Takayasu arteritis (mean 871.4 ng/ml, P<0.01) compared with controls (mean 607.9 ng/ml). No difference was found in soluble inter cellular adhesion molecule-1 levels between these two groups. Comparison of soluble vascular cell adhesion molecule-1 and inter cellular adhesion molecule-1 in these patients subdivided by age into three groups indicated significantly higher levels of these molecules in individuals over 50 years old compared to those under 39 years old (P<0.05). These data suggest that the measurement of soluble vascular cell adhesion molecule-1 may be clinically important in Takayasu arteritis. The correlation of soluble vascular cell adhesion molecule-1 and inter cellular adhesion molecule-1 levels with age may indicate some relationship with progression of this disease.

Expression of integrins in experimental autoimmune neuritis and Guillain-Barré syndrome

Integrins are a subclass of adhesion molecules that mediate cell-cell and cell-extracellular matrix interactions. Integrins influence transendothelial migration of lymphocytes and monocytes and are suitable targets for experimental immunotherapy. They are critically involved in the pathogenesis of autoimmune neuritis and abnormally expressed in human neuropathies. Also, the role of integrins in myelination, neurite outgrowth, and nerve regeneration suggests that they could be involved in the recovery phase of immune-mediated neuropathies. We investigated by immunohistochemistry the expression of a number of integrin subunits during the course of experimental autoimmune neuritis (EAN). Results were compared with the human immune neuropathy Guillain-Barre syndrome (GBS) and extended in vitro. Inflammation and demyelination in both EAN and GBS induced the down-regulation of beta4 integrin in Schwann cells (SCs), whereas loss of alpha2 was noted only in EAN. When axonal loss was present, SCs displayed alpha5 integrin, in both EAN and GBS. In vitro, basal lamina and inflammatory cytokines modulated the expression of beta4 in SCs, but they did not influence alpha2 and alpha5 expression. Finally, integrins were differentially expressed in blood vessels during EAN. In conclusion, the spatiotemporal changes in integrin expression may be used to characterize, stage, and better understand the pathogenesis and evolution of inflammation during GBS and EAN. This may help to establish useful, novel therapy for immune-mediated neuropathies.

Monoclonal antibodies against ICAM-1 and CD18 attenuate cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits

BACKGROUND AND PURPOSE

Inflammatory responses have been implicated in the elaboration of several forms of central nervous system injury, including cerebral vasospasm after subarachnoid hemorrhage (SAH). A critical event participating in such responses is the recruitment of circulating leukocytes into the inflammatory site. Two of the key adhesion molecules responsible for the attachment of leukocytes to endothelial cells are intercellular adhesion molecule-1 (ICAM-1) and the common beta chain of the integrin superfamily (CD18). This study examined the effects of monoclonal antibodies on ICAM-1 and the effects of CD18 on cerebral vasospasm after SAH.

METHODS

A rabbit model of SAH was utilized to test the influence of intracisternally administered antibodies to ICAM-1 and CD18 on cerebral vasospasm. Antibodies were administered alone or in combination, and the cross-sectional area of basilar arteries was assessed histologically on day 2 post-SAH.

RESULTS

Treatment with antibodies to ICAM-1 or CD18 inhibited vasospasm by 22% and 27%, respectively. When administered together, the attenuation of vasospasm increased to 56%. All of these effects achieved statistical significance.

CONCLUSIONS

These findings provide the first evidence that the severity of cerebral vasospasm can be attenuated using monoclonal antibodies against ICAM-1 and CD18. The results reinforce the concept that cell-mediated inflammation plays an important role in cerebral vasospasm after SAH and suggest that therapeutic targeting of cellular adhesion molecules can be of benefit in treating cerebral vasospasm.

Skeletal muscle immune deposits in systemic lupus erythematosus. Correlation with histologic changes, autoantibodies, and clinical involvement

Skeletal muscle biopsy and autopsy samples of 132 SLE patients were studied by immunofluorescence and light microscopic techniques. Immune deposits were compared to histologic abnormalities and clinical and serologic findings. Immune deposits with a mainly granular pattern were observed at different locations in 49 patients (37%). They correlated significantly (p<0.001) with inflammatory myopathy, demonstrated in 33(25%), with noninflammatory myopathy which occurred in 38 (29%) vasculitis, observed in 13(10%), and with noninflammatory vasculopathy which was noted in 10 patients (8%). The correlation of muscle immune deposits with anti-DNA antibodies was significant at p= 0.016. Anti-Sm and anti-U1 RNP antibodies were associated significantly with the intensity of immune deposits. Furthermore, a correlation of immune deposits with increased creatine phosphokinase and myopathic electromyogram, but not with evidence of clinical involvement, was shown. A key pathogenetic role of immune deposits in the development of skeletal muscle histologic abnormalities in SLE was demonstrated.

Dynamic pattern of endothelial cell adhesion molecule expression in muscle and perineural vessels from patients with classic polyarteritis nodosa

OBJECTIVE

To investigate endothelial cell adhesion molecule expression in vessels from patients with classic polyarteritis nodosa (PAN).

METHODS

Frozen sections of 21 muscle and 16 nerve samples from 30 patients with biopsy-proven PAN and 12 histologically normal muscle and 2 histologically normal nerve samples from 12 controls were studied immunohistochemically, using specific monoclonal antibodies (MAb) that recognize adhesion molecules. Adhesion molecules identified were intercellular adhesion molecule 1 (ICAM-1), ICAM-2, ICAM-3, vascular cell adhesion molecule 1 (VCAM-1), platelet endothelial cell adhesion molecule 1 (PECAM-1), E-selectin, P-selectin, L-selectin, lymphocyte function-associated antigen 1 (LFA-1), and very late activation antigen 4 (VLA-4). Neutrophils were identified with a MAb recognizing neutrophil elastase. Endothelial cells were identified with the lectin ulex europaeus.

RESULTS

In early lesions, expression of PECAM-1, ICAM-1, ICAM-2, and P-selectin was similar to that in control samples, and VCAM-1 and E-selectin were induced in vascular endothelium. In advanced lesions, immunostaining for adhesion molecules diminished or disappeared in luminal endothelium, whereas these molecules were clearly expressed in microvessels within and surrounding inflamed vessels. Staining in endothelia from vessels in a healing stage tended to be negative. A high proportion of infiltrating leukocytes expressed LFA-1 and VLA-4, and only a minority expressed L-selectin. No relationship between the expression pattern of adhesion molecules and clinical features, disease duration, or previous corticosteroid treatment was observed.

CONCLUSION

Endothelial adhesion molecule expression in PAN is a dynamic process that varies according to the histopathologic stage of the vascular lesions. The preferential expression of constitutive and inducible adhesion molecules in microvessels suggests that angiogenesis contributes to the persistence of inflammatory infiltration in PAN.

Effects of intravenous methylprednisolone therapy on leukocyte and soluble adhesion molecule expression in MS

Intravenous methylprednisolone (IVMP) may inhibit inflammatory cell recruitment to active MS lesions by effects on leukocyte or endothelial cell adhesion molecule expression. We investigated 15 MS patients in relapse receiving a 5-day course of IVMP (500 mg/day) and 15 normal subjects. Patients' blood samples were obtained pretreatment, at 6 and 24 hours after the first dose, and 48 hours after completion of therapy. Levels of L-selectin, leukocyte functional antigen 1 (LFA-1), Mac-1, and very late activation antigen 4 (VLA-4) expression were determined on alphabeta and gammadelta T cells and monocytes by dual-color immunofluorescent flow cytometry. Serum levels of soluble (s) L-selectin, sE-selectin, soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vascular cell adhesion molecule 1 (sVCAM-1) were measured by ELISA. There was a marked decrease in the T-cell and monocyte counts at 6 hours after therapy, with recovery to baseline at 24 to 48 hours. Adhesion molecule expression was normal on circulating T cells and monocytes in active MS. IVMP resulted in significant changes in the percent adhesion molecule expression on monocytes: increased L-selectin expression at 24 hours, decreased Mac-1 expression at 6 hours, and decreased VLA-4 expression at 6 hours and 24 hours following treatment. T-cell adhesion molecule expression was unaffected by the therapy. Serum sE-selectin was reduced at 6 hours and 24 hours following treatment. IVMP alters the distribution and kinetics of monocyte adhesion molecule expression and endothelial cell release of E-selectin, which may limit monocyte recruitment to areas of tissue destruction in MS.

HLA-DR expression in peripheral neuropathies: the role of Schwann cells, resident and hematogenous macrophages, and endoneurial fibroblasts

The expression of HLA-DR and the macrophage marker CD 68 was studied in 44 sural nerve biopsies from patients with inflammatory and non-inflammatory neuropathies and controls using immunohistochemistry on non-osmicated semithin sections, a technique that has not been used before in such a biopsy study. Most HLA-DR-immunoreactive (ir) cells were fibroblasts, macrophages or perineural cells, some were perivascular and endothelial cells, and only few were Schwann cells. Counts of immunoreactive cells revealed (a) increased HLA-DR expression in severe as compared to less severe neuropathies and to controls, (b) no correlation between the numbers of HLA-DR-ir cells and CD 68-ir macrophages, and (c) no close correlation between diagnostic groups and the number of HLA-DR-ir cells, but higher numbers in inflammatory neuropathies. We conclude that endoneurial fibroblasts and macrophages as antigen-presenting cells may be mediators in various peripheral nerve diseases, not only in inflammatory disorders.

Endothelial-leukocyte adhesion molecules in human disease

An effective host response to infection or tissue damage requires focal accumulation of leukocytes. Leukocyte adhesion to the vessel wall, a key step in this process, depends on the ordered expression of specific endothelial cell surface molecules. The endothelial molecules that support adhesion include selectins that recognize leukocyte cell surface glycoconjugates as well as members of the immunoglobulin superfamily that interact with leukocyte integrins. Although inflammation can occur with minimal damage to the vessel wall and surrounding tissues, control mechanisms sometimes appear to fail, and the inflammatory response itself becomes a significant clinical problem. In this review, we discuss endothelial-leukocyte adhesion molecules with particular emphasis on their expression and function in human disease. Pathophysiological processes presented include atherosclerosis, ischemia-reperfusion injury, acute lung injury, rheumatoid arthritis, and graft rejection. A more detailed description of the discovery and characterization of the key molecules appears in the antecedent article entitled "Endothelial-Leukocyte Adhesion Molecules".

The expression of the adhesion molecules ICAM-1, VCAM-1, PECAM, and E-selectin in human atherosclerosis

The expression of PECAM, ICAM-1, VCAM-1, and E-selectin was studied in 64 samples of human coronary arteries taken from 15 explanted hearts obtained within 5 min of transplantation. Normal artery (n = 12), predominantly fibrous plaques (n = 23), and plaques containing extracellular lipid (n = 26) and three segments showing recanalization channels were studied. All endothelial cells strongly and equally expressed PECAM; positive staining was used to check that artefactual denudation of the endothelial surface had not occurred. PECAM was also present in some lipid-filled macrophages. Normal arteries showed no VCAM-1 staining but focal segments of the endothelium were positive for ICAM-1 and E-selectin. ICAM-1 was strongly and constantly expressed by the endothelium over all types of plaques and in macrophages. E-selectin expression was confined to endothelial cells and occurred on the surface in 35 per cent of fibrous and 22 per cent of lipid-containing plaques. VCAM-1 staining of surface endothelium occurred in 39 per cent of fibrous and 20 per cent of lipid-containing plaques. A population of spindle-shaped cells of macrophage type (positive for EMB11 antigen) expressed VCAM-1 in lipid-containing plaques. Adventitial vessels adjacent to plaques showed endothelial expression of ICAM-1 and E-selectin. VCAM-1 staining of adventitial vessel endothelium was associated with local lymphoid aggregation. In conclusion, the expression of cell adhesion molecules is an important element in the inflammatory component of atherosclerosis and contributes to both monocyte and lymphocyte activation and recruitment from adventitial vessels and the arterial lumen.