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Biomedical subjects

R Lobb

Publications and source records attributed to R Lobb.

At least 19 recordsLinked to original sources
PubMed2001

EatSmart: efficacy of a multifaceted preventive nutrition intervention in clinical practice.

BACKGROUND: We evaluated a multifaceted preventive nutrition intervention to improve dietary habits among adult primary care patients. METHODS: We randomized six group practices in a managed care organization. Participants completed baseline and 3-month follow-up surveys. The intervention comprised (1) mailed personalized dietary recommendations and educational booklets focusing on fruits and vegetables, red meat, and dairy foods, tailored to patients' baseline intake and stage of readiness to change eating behaviors; (2) verbal endorsement by the primary care provider of the benefits of these recommendations; and (3) two motivational counseling sessions with telephone counselors to set dietary goals. RESULTS: Among the 230 subjects in the intervention group and 274 in the control group, mean age was 54 years, 70% were female, and 91% were white and 7% African American. Eighty-nine percent of the participants completed the follow-up survey. We measured change in intake of foods using results from the baseline and follow-up food frequency questionnaires. Using an intention-to-treat analysis and adjusting for age, sex, race, and baseline intake, the change in fruit and vegetable intake in the intervention group was 0.6 (95% confidence interval 0.3, 0.8) servings/day higher than in the control group. There was no intervention effect on red meat and dairy products. CONCLUSIONS: Tailored clinical nutrition interventions that combine brief physician endorsement with practice supports may be effective in changing patients' eating behavior.

Diet↗
PubMed2001

Process evaluation of a clinical preventive nutrition intervention.

BACKGROUND: We report process data on the feasibility of delivering a clinical preventive nutrition intervention that was effective in increasing participants' consumption of fruits and vegetables. We also examine relationships between process variables and study outcomes. METHODS: We randomly assigned six practice sites in a managed care organization to a dietary intervention or control condition. We invited adults 18 years of age or older scheduled for routine health visits within the subsequent 2 months to participate. Of the 566 patients we contacted from the intervention sites, 230 (41%) enrolled. From the control sites, we contacted 617, and 274 (44%) enrolled. Intervention participants received a tailored letter providing feedback on their consumption of target foods together with recommendations for improvement, stage-matched nutrition education booklets, a diet-health endorsement from their primary care providers (PCPs), and two motivational counseling telephone calls. Of enrollees, 195 (85%) in the intervention group and 252 (92%) in the control group returned the final survey 3 months later. RESULTS: Seventy-one percent of both participants and PCPs reported that the PCPs had discussed the relationship between diet and health at their visit. Fifty-seven percent of participants and 62% of PCPs reported that they discussed the complete diet-health endorsement, which included: (1) acknowledgment of the relationship between diet and health and (2) tailored study recommendations. The inclusion of both parts of the diet-health endorsement, but not the length of time spent, appeared to correlate with healthful outcomes. CONCLUSIONS: These process data suggest that the brief PCP diet-health endorsement contributed to the intervention effect on fruits and vegetables.

Counseling↗
PubMed2001

PrimeScreen, a brief dietary screening tool: reproducibility and comparability with both a longer food frequency questionnaire and biomarkers.

OBJECTIVE: Diet is an important determinant of health outcomes, but physicians have few ways to identify persons with suboptimal diets. The purposes of this study were to examine the reproducibility of a short dietary assessment questionnaire (PrimeScreen) and to compare its results with those of a longer food frequency questionnaire and with plasma levels of selected nutrients. DESIGN: Each subject completed two PrimeScreen questionnaires at an interval of 2 weeks and one full length, 131-item, semiquantitative food frequency questionnaire (SFFQ), and had a sample of blood drawn. We compared the PrimeScreen with two reference standards, the SFFQ and plasma levels of selected nutrients. SETTING: A large managed care organization in New England. SUBJECTS: A total of 160 men and women, aged 19-65 years, participated. RESULTS: For foods and food groups, the mean correlation coefficient (r) was 0.70 for reproducibility and 0.61 for comparability with the SFFQ. For nutrients, the mean r was 0.74 for reproducibility and 0.60 for comparability with the SFFQ. No substantial differences were evident by sex, race, body mass index, occupation or education. Correlation coefficients for the comparison of vitamin E, beta-carotene and lutein/zeaxanthin intakes from the PrimeScreen with plasma levels were 0.33, 0.43 and 0.43, respectively. These values were similar to those comparing the SFFQ with plasma levels. The median time to complete PrimeScreen was 5 min; 87% of participants required fewer than 10 min. CONCLUSIONS: A quick way to assess quality of diet among adults, PrimeScreen has adequate reproducibility and its results compare well with a longer food frequency questionnaire and biomarkers.

Adult↗
PubMed2000

The Src kinase p56(lck) up-regulates VLA-4 integrin affinity. Implications for rapid spontaneous and chemokine-triggered T cell adhesion to VCAM-1 and fibronectin.

In circulating lymphocytes, the VLA-4 integrin preexists in multiple affinity states that mediate spontaneous tethering, rolling, and arrest on its endothelial ligand, vascular cell adhesion molecule-1 (VCAM-1). The regulation and function of VLA-4 affinity in lymphocytes has never been elucidated. We show here that p56(lck), the major Src kinase in T cells, is a key regulator of high affinity VLA-4. This high affinity is essential for the rapid development of firm adhesion of resting T cells to VCAM-1 and to their extracellular matrix ligand, fibronectin. Lck-regulated VLA-4 function does not require intact TCR nor several key components of the TCR signaling pathway, including ZAP-70 and SLP-76. Furthermore, stimulation of p56(lck) by the phosphatase inhibitor, pervanadate, triggers firm VLA-4-dependent adhesion to VCAM-1. Although Lck is not required for chemokine receptor signaling to mitogen-activated protein kinase, the presence of Lck-regulated high affinity VLA-4 also facilitates firm adhesion triggered by the chemokine, SDF-1, at short-lived contacts. Surprisingly, bond formation rates, ability to tether cells to VLA-4 ligand, and VLA-4 tether bond stability under shear flow are not affected by VLA-4 affinity or Lck activity. Thus, the ability of high affinity VLA-4 to arrest cells on VCAM-1 under flow arises from instantaneous post-ligand strengthening rather than from increased kinetic stability of individual VLA-4 bonds. These results suggest that p56(lck) maintains high affinity VLA-4 on circulating lymphocytes, which determines their ability to strengthen VLA-4 adhesion and rapidly respond to proadhesive chemokine signals at endothelial sites.

Blotting, Western↗
PubMed1999

VCAM-1 and ICAM-1 mediate leukocyte-endothelial cell adhesion in rat experimental colitis.

BACKGROUND & AIMS: The molecular mechanisms responsible for leukocyte recruitment in experimental colitis are poorly understood. The aims of this study were to measure expression of endothelial intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) and to determine their role in leukocyte recruitment in experimental colitis. METHODS: Rats with trinitrobenzene sulfonic acid (TNBS)-induced colitis and control rats were studied 1, 7, or 21 days after treatment. ICAM-1 and VCAM-1 expressions were measured by the double radiolabeled antibody technique. Leukocyte-endothelial cell interactions were determined in colonic venules by fluorescence intravital microscopy. Therapeutic effects of treatment with anti-VCAM-1 antibodies were also assessed. RESULTS: Colonic endothelial ICAM-1 was constitutively expressed and did not increase in colitic animals. In contrast, constitutive expression of VCAM-1 was low but markedly increased (6-fold) 1 and 7 days after induction of colitis. Increased colonic expression of VCAM-1 paralleled macroscopic damage score, myeloperoxidase activity, and increased leukocyte adhesion in colonic venules. The latter was significantly decreased by immunoneutralization of ICAM-1 and completely abrogated by immunoneutralization of VCAM-1. Long-term administration of anti-VCAM-1 antibody resulted in significant attenuation of colitis. CONCLUSIONS: Induction of colitis in rats by TNBS is followed by up-regulation of endothelial VCAM-1. VCAM-1 and constitutive ICAM-1 are major determinants of leukocyte recruitment to the inflamed intestine.

Animals↗
PubMed1998

The role of the very late antigen-4 and its counterligand vascular cell adhesion molecule-1 in the pathogenesis of experimental autoimmune neuritis of the Lewis rat.

We have investigated the functional role of very late antigen-4 [VLA-4 (alpha4/beta1) integrin] and vascular cell adhesion molecule-1 (VCAM-1) in experimental autoimmune neuritis (EAN), an animal model of the Guillain-Barré syndrome, using neutralizing monoclonal antibodies (mAbs) as probes. Disease was induced by intravenous adoptive transfer of P2 specific T cells (AT-EAN), or by immunization with bovine myelin (active EAN). Preventive treatment with 500 microg anti-VLA-4 mAb (TA-2) or with an isotype control antibody was given in AT-EAN 4 h before cell transfer and at day 3. Intravenous injection of 500 microg anti-VCAM-1 mAb (5F10) or a corresponding isotype control was given in AT-EAN 4 h before disease induction, and at days 2, 4 and 6. Preventive treatment of active EAN with mAb to VLA-4 or VCAM-1 was performed at days 5, 9 and 13. On immunohistochemical examination, VCAM-1 in sciatic nerve was found to be upregulated at early stages of EAN (days 3-5 after T-cell transfer), whilst no expression was noted in healthy controls. In both EAN models, blockade of VLA-4 markedly attenuated disease severity. Blockade of VCAM-1 also significantly ameliorated the disease course and diminished T-cell infiltration in sciatic nerve, but to a lesser degree. These experiments demonstrate the critical role of VLA-4 in the pathogenesis of EAN and show that upregulation of VCAM-1 expression contributes, at least in part, to the progression of the disease in the early stages. Future studies are needed to assess the potential contribution of other VLA-4 ligands.

Animals↗
PubMed1995

Single-base sequencing and similarity comparisons.

A "single-base sequence" is a DNA sequence in which the identities and locations of bases of only one type have been determined. We present experimental procedures for single-base sequencing and describe the effective use of existing software (FASTA) in similarity comparisons of single-base sequences. We determined the theoretical and experimental minimum sequence lengths required for identification of a sequence within a large dataset and optimized the FASTA parameters for use in single-base similarity comparisons. Single-base sequences have been used to identify cDNAs occurring in a database. Single-base sequencing could be used to reduce the redundancy of "shot-gun sequencing."

Databases, Factual↗
PubMed1995

Domains 1 and 4 of vascular cell adhesion molecule-1 (CD106) both support very late activation antigen-4 (CD49d/CD29)-dependent monocyte transendothelial migration.

We investigated the role of the 6 domain (6D) and 7 domain (7D) forms of human VCAM-1 as counter-receptors for the alpha 4 beta 1 integrin (VLA-4) in monocyte migration induced by C5a. Across Chinese hamster ovary (CHO) cell monolayers transfected with VCAM-6D or VCAM-7D, monocyte migration was not inhibited by treatment of monocytes with mAb to CD18. Addition of mAb to alpha 4 to the CD18 mAb inhibited monocyte migration by 90% across CHO VCAM-6D and CHO VCAM-7D. mAbs to domain 1 (4B9) or domain 4 (GH12) of VCAM-1 each inhibited migration across CHO VCAM-7D partially, when monocytes were also treated with anti-CD18 mAb. When the VCAM-1 mAbs were combined, migration of these monocytes across CHO VCAM-7D was further inhibited to the same degree as with mAbs to alpha 4 plus CD18. IL-1-treated human umbilical vein endothelium (HUVE) supported CD18-independent, VLA-4-mediated monocyte migration to C5a. A mAb to domain 1 of VCAM-1 almost completely inhibited the CD18-independent migration across HUVE activated with IL-1 for 2 h or 20 h, but was less inhibitory when HUVE was treated with IL-1 for 5 h. However, when mAbs to domain 1 and domain 4 were combined, CD18-independent migration was inhibited completely under all conditions tested. These results suggest that either domain 1 or domain 4 of VCAM-1 can mediate VLA-4-dependent monocyte transendothelial migration, that VLA-4 interaction with these two domains can account for all of the VLA-4-mediated migration, and that the expression of VCAM-1 variants on HUVE depends partly on the duration of IL-1 activation.

Animals↗
PubMed1995

The human and mouse homologs of the yeast RAD52 gene: cDNA cloning, sequence analysis, assignment to human chromosome 12p12.2-p13, and mRNA expression in mouse tissues.

The yeast Saccharomyces cerevisiae RAD52 gene is involved in DNA double-strand break repair and mitotic/meiotic recombination. The N-terminal amino acid sequence of yeast S. cerevisiae, Schizosaccharomyces pombe, and Kluyveromyces lactis and chicken is highly conserved. Using the technology of mixed oligonucleotide primed amplification of cDNA (MOPAC), two mouse RAD52 homologous cDNA fragments were amplified and sequenced. Subsequently, we have cloned the cDNA of the human and mouse homologs of yeast RAD52 gene by screening cDNA libraries using the identified mouse cDNA fragments. Sequence analysis of cDNA derived amino acid revealed a highly conserved N-terminus among human, mouse, chicken, and yeast RAD52 genes. The human RAD52 gene was assigned to chromosome 12p12.2-p13 by fluorescence in situ hybridization, R-banding, and DNA analysis of somatic cell hybrids. Unlike chicken RAD52 and mouse RAD51, no significant difference in mouse RAD52 mRNA level was found among mouse heart, brain, spleen, lung, liver, skeletal muscle, kidney, and testis. In addition to an approximately 1.9-kb RAD52 mRNA band that is present in all of the tested tissues, an extra mRNA species of approximately 0.85 kb was detectable in mouse testis.

Amino Acid Sequence↗
PubMed1995

Vascular cell adhesion molecule (VCAM)-Ig fusion protein defines distinct affinity states of the very late antigen-4 (VLA-4) receptor.

The Very Late Antigen-4 receptor (VLA-4) (alpha 4 beta 1) is constitutively expressed on leukocytes and plays a role in cell trafficking, activation and development through its interaction with two alternative ligands, Vascular Cell Adhesion Molecule (VCAM-1) and fibronectin (FN). VLA-4-dependent cell adhesion is augmented by various stimuli, such as divalent cations, certain beta 1-specific monoclonal antibodies (mAbs) and cell activation. However, the steps of the adhesive process which they affect are currently undefined. In order to investigate whether or not these stimuli affect the primary step, VLA-4/ligand binding, we employed a recombinant VCAM-IgG fusion protein (VCAM-Ig) as a soluble ligand for VLA-4. Using this soluble ligand, we have directly demonstrated that the VLA-4 receptor can exist in at least three different affinity states on the cell surface. Two distinct high affinity states are induced on normal peripheral blood T cells, one by the anti-beta 1 mAb TS2/16, and one of 15-20 fold higher affinity by the divalent cation Mn2+. Interestingly, activation through the T cell receptor (TcR), through CD31 or by the Macrophage Inflammatory Protein-1 beta chemokine (MIP-1 beta) do not detectably increase VLA-4 affinity although they do augment VLA-4 dependent cell adhesion in vitro. Thus, VCAM-Ig binding defines high affinity VLA-4 receptors, revealing unique effects of the TS2/16 mAb and Mn2+ cations in vitro, and distinguishes VLA-4/VCAM interactions from subsequent steps in cell adhesion.

Animals↗
PubMed1995

Lung eosinophilia is dependent on IL-5 and the adhesion molecules CD18 and VLA-4, in a guinea-pig model.

Blood and tissue-eosinophilia is a characteristic feature of a number of disease states. In experimental animals, the intravenous injection of parasitic larvae induces a profound eosinophilia that can be mimicked by the intravenous injection of Sephadex particles. In the present study, this procedure was used to investigate the mechanisms involved in the development of lung eosinophilia in a guinea-pig model. Intravenous administration of Sephadex particles to guinea-pigs resulted in a significant increase in the influx of eosinophils in the airways and in lung tissue eosinophil peroxidase (EPO) activity (at t = 24 hr). An anti-interleukin-5 (IL-5) monoclonal antibody (mAb) totally inhibited the eosinophilia in the airways and significantly reduced the lung tissue EPO activity. The concomitant accumulation of neutrophils and mononuclear cells, however, was not affected by this treatment. Monoclonal antibodies to VLA-4 and CD18 caused 58% and 62% suppression of eosinophilia in the bronchoalveolar lavage (BAL), respectively, whilst having no effect on lung tissue EPO activity. Co-administration of the two mAb resulted in total inhibition of eosinophil accumulation into BAL and significant suppression of lung tissue EPO activity (55% inhibition). This procedure also resulted in 72% inhibition of mononuclear cell influx and 68% inhibition of neutrophil influx in the BAL, the latter effect being entirely due to the actions of the anti-CD18 mAb. The results of this study indicate for the first time a requirement for IL-5 in the development of lung eosinophilia in this model. Further, it is clear that both the molecules VLA-4 and CD18 contribute to the development of this response and that maximal inhibition of lung eosinophilia is achieved only when the two adhesion pathways are simultaneously blocked.

Animals↗
PubMed1993

The ELAM ligand fucosyltransferase, ELFT, directs E-selectin binding to a secreted scaffold protein: a method to produce and purify large quantities of specific carbohydrate structures.

Many biological processes depend on cell surface recognition of receptor-ligand pairs. Some receptors, such as the selectins, recognize specific carbohydrate structures as part of their ligands. The ability to synthesize such ligands for use in the study of cell adhesion mechanisms or as inhibitors of a variety of pathological conditions would be extremely useful. However, the chemical or enzymic in vitro synthesis of carbohydrate-based ligands has thus far been difficult and costly. We have used E-selectin and its carbohydrate ligand as a model system to test if it is possible to express specific carbohydrate structures on a secreted, glycosylated and easily purified scaffold protein and to use this newly modified protein as a functional adhesion molecule. We co-expressed a fucosyltransferase (ELFT) and a secreted immunoglobulin-LFA3 fusion protein (LFA31G) in the same cell to modify the carbohydrate structures on the secreted LFA3IG scaffold protein (we refer to this novel protein as X-LFA3IG). Using glycosidase digestion, lectin binding, carbohydrate composition analysis and antibody-binding assays, we show that approximately 50% of the potential N-linked carbohydrate sites on X-LFA3IG are, indeed, modified and that the modification is the addition of fucose. Furthermore, we show that X-LFA3IG contains epitopes recognized by anti-Slex antibodies, and, using an E-selectin-specific adhesion assay, we demonstrate that X-LFA3IG is a functional ligand for E-selectin. This in vivo approach for generating specific carbohydrate structures could be generalized to produce and purify large quantities of other biologically important carbohydrate structures.

Antibodies↗
PubMed1993

Cloning of an inflammation-specific phosphatidyl inositol-linked form of murine vascular cell adhesion molecule-1.

Vascular cell adhesion molecule-1 (VCAM1) is a member of the immunoglobulin (Ig) superfamily which interacts with the integrin very late antigen-4 (VLA4). The VCAM1/VLA4 interaction mediates both adhesion and signal transduction and is thought to play an important role in inflammatory and immune responses in vivo. VCAM1 cDNAs cloned from mouse, rat, rabbit, and human libraries contain six, seven, or eight extracellular Ig-like domains generated by alternate splicing, but to date shorter forms have not been found. We have cloned a novel cDNA encoding only the three N-terminal domains of murine VCAM1 followed by a unique C-terminal tail generated by alternate splicing of a previously undescribed exon. This truncated form of murine VCAM1 (3D-VCAM1) is expressed in COS cells as a functional adhesion molecule which is lost from the cell surface following treatment with phosphatidylinositol-specific phospholipase C. 3D-VCAM1 is found only in endotoxin-treated but not control murine and rat tissues. Thus in rodents alternate splicing of the VCAM1 gene generates a unique truncated inflammation-specific phosphatidylinositol-linked form of VCAM1.

Alternative Splicing↗
PubMed1993

Expression of vascular cell adhesion molecule-1 in kidney allograft rejection.

VCAM-1, a leukocyte adhesion molecule expressed by cytokine-activated endothelial cells in culture, may mediate mononuclear leukocyte infiltration in vessels and interstitium in solid organ allograft rejection. Using the avidin-biotin immunoperoxidase technique and an affinity-purified rabbit polyclonal antisera to recombinant human VCAM (rVCAM Ab) which works in methyl Carnoy's fixed tissues, we studied the expression of this molecule in biopsies of transplanted kidneys (N = 34) with and without features of rejection and allograft nephrectomies (N = 17) as well as nontransplanted control tissues (N = 26). The rVCAM Ab showed a population of reactive endothelial cells limited to sites of prominent subendothelial leukocytic cell infiltration in arteries and veins, and occasional peritubular capillaries (PTC) in rejecting allografts. Endothelial expression of VCAM was rarely identified in biopsies showing interstitial rejection only or cyclosporine toxicity, usually in PTC, and was only rarely encountered in nontransplanted control tissues. Apparent de novo expression of VCAM-1 by arterial smooth muscle cells and mesangial cells was present in cases of severe rejection. In addition, a population of cells (DC) with dendritic morphology was identified by rVCAM Ab within sites of lymphoid cell aggregation in rejecting allografts. Further evidence that these cells represent true DC was obtained by identification of VCAM-1 positive, morphologically similar cells in both germinal centers and interfollicular areas of all seven reactive lymph nodes tested; and by similar staining of these cells in the allografts and lymph nodes by antibodies to nerve growth factor receptor and the complement receptor CR1, previously shown to recognize DC. DCs were generally not seen in uninflamed normal control organs or portions of allografts uninvolved by lymphoid aggregates. Enhanced tubular epithelial cell expression of VCAM-1 was also present in rejecting allografts. All staining could be abolished by absorption of the antisera with VCAM-1 transfected, but not ICAM-1 or ELAM-1 transfected, CHO cells. In situ hybridization studies utilizing a cDNA probe to human VCAM-1 demonstrated mRNA production by glomerular, tubular and vascular cells corresponding to sites where the protein was immunohistochemically localized.(ABSTRACT TRUNCATED AT 400 WORDS)

Arteries↗
PubMed1993

Attenuation of colitis in the cotton-top tamarin by anti-alpha 4 integrin monoclonal antibody.

Recent studies have demonstrated the induced expression of endothelial adhesion molecules including E-selectin (also called endothelial leukocyte adhesion molecule-1), vascular cell adhesion molecule and intercellular adhesion molecule in actively involved mucosa of patients with ulcerative colitis and Crohn's disease. Similar induction has been demonstrated in the colon of the Cotton-top tamarin (CTT), a New World primate that experiences a spontaneous acute and chronic colitis resembling ulcerative colitis. To assess the potential importance of leukocyte adhesion as a necessary step in acute colitis, the effect of parenteral mAb directed against adhesion molecules on CTT colitis was evaluated in placebo-controlled blinded trials. Serial administration of either of two anti-E-selectin mAb designated BB11 and EH8 effectively coated endothelial surfaces expressing this vascular adhesion molecule. Although colitis activity was slightly diminished after the 10-d treatment period in CTT receiving either BB11 or EH8, this reduction was not significantly different than that seen in animals given a placebo control when assessed by a previously validated standardized scale of inflammatory activity: mean histologic activity grade 2.2 +/- 0.2 pretreatment vs 1.5 +/- 0.5 posttreatment in group receiving mAb and 2.1 +/- 0.1 pretreatment vs 1.3 +/- 0.5 posttreatment in the placebo group (P > 0.2). In contrast, administration of an anti-alpha 4 integrin mAb designated HP1/2 that binds VLA4 (alpha 4 beta 1) and presumably alpha 4 beta 7 integrins resulted in significant attenuation of acute colitis when compared to both pretreatment activity index (P = 0.005) and the placebo control group (P < 0.01): mean histologic activity grade 1.6 +/- 0.3 pretreatment vs 0.2 +/- 0.1 posttreatment in the group receiving HP1/2 and 1.8 +/- 0.5 pretreatment and 1.2 +/- 0.2 posttreatment in the placebo control group. These studies using a model of spontaneous colitis in the CTT demonstrate the feasibility of modulation of leukocyte-vascular adhesion and/or other integrin-mediated events possibly including T cell aggregation and T cell-stromal interactions, as well as lymphocyte homing. These results suggest both that these processes are important and possibly essential elements in sustaining acute colitis and that their disruption may result in therapeutic benefit.

Animals↗
PubMed1993

Expression of vascular cell adhesion molecule (VCAM-1) in liver and pancreas allograft rejection.

VCAM-1, a leukocyte adhesion molecule expressed by cytokine-activated endothelial cells in culture, may mediate mononuclear leukocyte infiltration in vessels and interstitium in solid organ allograft rejection. Using the avidin-biotin immunoperoxidase technique and two different antibodies--4B9, a murine monoclonal antibody, and rabbit polyclonal antisera to recombinant human VCAM (rVCAM Ab), which work in methacarn-fixed tissues--we studied the expression of this molecule in biopsies of transplanted liver and pancreas with and without features of rejection as well as nontransplant control tissues. The rVCAM Ab, but not 4B9, showed a population of reactive endothelial cells limited to sites of prominent subendothelial leukocytic cell infiltration in arteries and veins in rejecting allografts. VCAM-1 expression by sinusoidal endothelium in rejecting liver allografts was also observed. In addition, a population of cells (DC) with dendritic morphology was identified by rVCAM Ab within sites of lymphoid cell aggregations in both liver and pancreas allografts. Further evidence that these cells represent true DC was obtained by identification of VCAM-1 positive morphologically similar cells in both germinal centers and interfollicular areas of reactive lymph nodes; and by similar staining of these cells in allograft organs by a monoclonal antibody to nerve growth factor receptor, previously shown to recognize DC. DCs were generally not seen in normal control organs or portions of allografts uninvolved by lymphoid aggregates. This study provides evidence that 1) endothelial cell expression of VCAM-1 may be important in transplant rejection, 2) different epitopes of VCAM-1 may be preserved in tissue sections and recognized by different antibodies, and 3) there is probably a population of VCAM-1 expressing DC that participates in the cellular rejection progress.

Antibodies, Monoclonal↗
PubMed1992

Leukocyte accumulation promoting fibrin deposition is mediated in vivo by P-selectin on adherent platelets.

The glycoprotein P-selectin is a cell adhesion molecule of stimulated platelets and endothelial cells, which mediates the interaction of these cells with neutrophils and monocytes. It is a membrane component of cell storage granules, and is a member of the selectin family which includes E-selectin and L-selectin. P-selectin recognizes both lineage-specific carbohydrate ligands on monocytes and neutrophils, including the Lewis x antigen, sialic acid, and a protein component. In inflammation and thrombosis, P-selectin may mediate the interaction of leukocytes with platelets bound in the region of tissue injury and with stimulated endothelium. To evaluate the role of P-selectin in platelet-leukocyte adhesion in vivo, the accumulation of leukocytes within an experimental thrombus was explored in an arteriovenous shunt model in baboons. A Dacron graft implanted within an arteriovenous shunt is thrombogenic, accumulating platelets and fibrin within its lumen. These bound platelets express P-selectin. Here we show that antibody inhibition of leukocyte binding to P-selectin expressed on platelets immobilized on the graft blocks leukocyte accumulation and inhibits the deposition of fibrin within the thrombus. These results indicate that P-selectin is an important adhesion molecule on platelets, mediating platelet-leukocyte binding in vivo, that the presence of leukocytes in thrombi is mediated by P-selectin, and that these leukocytes promote fibrin deposition.

Animals↗