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Biomedical subjects

K D Patel

Publications and source records attributed to K D Patel.

At least 19 recordsLinked to original sources
PubMed2001

Shear-dependent eosinophil transmigration on interleukin 4-stimulated endothelial cells: a role for endothelium-associated eotaxin-3.

Leukocyte infiltration into inflammatory sites is regulated by the expression of adhesion and activation proteins, yet the role of these proteins in shear-dependent transmigration is poorly understood. We examined eosinophil recruitment on cytokine-stimulated human umbilical vein endothelial cells (HUVECs) under laminar flow conditions. Eosinophils rapidly transmigrated on interleukin (IL)-4-, but not TNF-stimulated HUVECs. Transmigration was shear dependent, with up to 90% of eosinophils transmigrating in the presence of shear and less than 25% of cells transmigrating under static conditions. Eosinophils express CC chemokine receptor CCR3 and are responsive to various CC chemokines. The effects of chemokines are mediated primarily through G(alpha)i, which is pertussis toxin sensitive. Greater than 65% of shear-dependent eosinophil transmigration on IL-4-stimulated HUVECs was blocked by either pertussis toxin or by an anti-CCR3 monoclonal antibody. Using reverse transcription polymerase chain reaction (RT-PCR) and Western blots, we found that IL-4-stimulated HUVECs produce both mRNA and protein for eotaxin-3. Eotaxin-3 was both released by HUVECs and expressed on the endothelial cell surface. Pretreatment of HUVECs with an anti-eotaxin-3 antibody blocked eosinophil transmigration to the same extent as an anti-CCR3 antibody. These results indicate that IL-4-stimulated HUVECs support shear-dependent eosinophil transmigration by upregulating eotaxin-3, and that surface association is critical for the role of eotaxin-3 in transmigration.

Adult↗
PubMed2001

Exclusive neutrophil recruitment with oncostatin M in a human system.

Oncostatin M (OSM), a member of the IL-6 family has been postulated to be a potent recruiter of leukocytes, however information regarding the molecular mechanism(s) underlying this event is extremely limited. Therefore, the aim of this study was to investigate the role of OSM-mediated leukocyte recruitment in a human system in vitro under flow conditions. A parallel-plate flow chamber assay was used to examine leukocyte recruitment from whole blood by human umbilical vein endothelium treated for 24 hours with OSM. OSM in a dose-response manner revealed very significant leukocyte rolling and adhesion reaching optimal levels at a very low concentration of OSM (10 ng/ml). The OSM-induced leukocyte rolling and adhesion was comparable to levels seen with tumor necrosis factor. OSM was extremely selective for neutrophil recruitment (96%) with <3% lymphocyte recruitment. By contrast, tumor necrosis factor-alpha revealed no such selectivity, recruiting 70% neutrophils and at least 25% lymphocytes and detectable levels of eosinophils at 24 hours. The molecular mechanism underlying the leukocyte recruitment seemed to be entirely dependent on P-selectin as leukocyte recruitment could be completely blocked by the addition of a P-selectin-blocking antibody. An elevation in both P-selectin message and protein was observed with 24 hours of OSM stimulation of endothelium. By contrast, E-selectin and VCAM-1 were not detectable after OSM stimulation. Similar results were seen with passaged dermal microvascular endothelium that does not have a prestored pool of P-selectin. Based on these results, we conclude that OSM may be a very selective potent recruiter of neutrophils in more prolonged inflammatory conditions, an event exclusively dependent on P-selectin.

Blood Physiological Phenomena↗
PubMed2000

Synergism of multiple adhesion molecules in mediating cytoadherence of Plasmodium falciparum-infected erythrocytes to microvascular endothelial cells under flow.

Plasmodium falciparum-infected erythrocytes (IRBCs) have been shown to interact with a number of endothelial adhesion molecules expressed on transfectants, on cell lines, and as immobilized purified receptor proteins under flow conditions. However, the experiments were designed in such a way that maximal numbers of adhesion molecules were provided as substratum. Whether the interactive events actually occur on microvascular endothelium, where the distribution and expression of adhesion molecules may be less, remains undetermined. In this study, the cytoadherance of IRBCs on human dermal microvascular endothelial cells (HDMECs) as a model of human microvasculature was examined. IRBCs were observed to tether, roll, and adhere on resting HDMECs, which constitutively expressed CD36 and intercellular adhesion molecule-1 (ICAM-1) at an optimal shear stress of 1 dyne/cm(2). Stimulation of HDMECs with tumor necrosis factor-alpha for 5 and 24 hours, which resulted in up-regulation of ICAM-1 and induction of vascular cell adhesion molecule-1 expression, significantly increased the percentage of rolling cells that adhered without affecting the rolling flux. In contrast, P-selectin expression on HDMECs induced by oncostatin M led to an increase in both rolling flux and adhesion. Inhibition studies with receptor-specific monoclonal antibodies revealed that adhesion of IRBCs on HDMECs was largely CD36 dependent, whereas rolling could be mediated by any of the adhesion molecules studied. Collectively, these findings indicate that IRBCs interact synergistically with multiple adhesion molecules on vascular endothelium. The rolling of IRBCs may be the rate-limiting step in cytoadherance, since it can be modulated by cytokines to enhance CD36-mediated IRBC adhesion.

Animals↗
PubMed2000

Transient translocation of the B cell receptor and Src homology 2 domain-containing inositol phosphatase to lipid rafts: evidence toward a role in calcium regulation.

Membrane microdomains (lipid rafts) are enriched in selected signaling molecules and may compartmentalize receptor-mediated signals. Here, we report that in primary human B lymphocytes and in Ramos B cells B cell receptor (BCR) stimulation induces rapid and transient redistribution of a subset of engaged BCRs to lipid rafts and phosphorylation of raft-associated tyrosine kinase substrates. Cholesterol sequestration disrupted the lipid rafts, preventing BCR redistribution, but did not inhibit tyrosine kinase activation or phosphorylation of mitogen-activated protein kinase/extracellular regulated kinase. However, raft disruption enhanced the release of calcium from intracellular stores, suggesting that rafts may sequester early signaling events that down-regulate calcium flux. Consistent with this, BCR stimulation induced rapid and transient translocation of the Src homology 2 domain-containing inositol phosphatase, SHIP, into lipid rafts.

B-Lymphocytes↗
PubMed2000

Noncovalent association of P-selectin glycoprotein ligand-1 and minimal determinants for binding to P-selectin.

P-selectin glycoprotein ligand-1 (PSGL-1) is a disulfide-bonded, homodimeric mucin ( approximately 250 kDa) on leukocytes that binds to P-selectin on platelets and endothelial cells during the initial steps in inflammation. Because it has been proposed that only covalently dimerized PSGL-1 can bind P-selectin, we investigated the factors controlling dimerization of PSGL-1 and re-examined whether covalent dimers are required for binding its P-selectin. Recombinant forms of PSGL-1 were created in which the single extracellular Cys (Cys(320)) was replaced with either Ser (C320S-PSGL-1) or Ala (C320A-PSGL-1). Both recombinants migrated as monomeric species of approximately 120 kDa under both nonreducing and reducing conditions on SDS-polyacrylamide gel electrophoresis. P-selectin bound similarly to cells expressing either wild type or mutated forms of PSGL-1 in both flow cytometric and rolling adhesion assays. Unexpectedly, chemical cross-linking studies revealed that both C320S- and C320A-PSGL-1 noncovalently associate in the plasma membrane and cross-linking generates dimeric species. Chimeric recombinants of PSGL-1 in which the transmembrane domain in PSGL-1 was replaced with the transmembrane domain of CD43 (CD43TMD-PSGL-1) could not be chemically cross-linked, suggesting that residues within the transmembrane domain of PSGL-1 are required for noncovalent association. Cells expressing CD43TMD-PSGL-1 bound P-selectin. To further address the ability of P-selectin to bind monomeric derivatives of PSGL-1, intact HL-60 cells were trypsin-treated, which generated a soluble approximately 25-kDa NH(2)-terminal fragment of PSGL-1 that bound to immobilized P-selectin. Because N-glycosylation of PSGL-1 hinders trypsin cleavage, a recombinant form of PSGL-1 was generated in which all three potential N-glycosylation sites were mutated (DeltaN-PSGL-1). Cells expressing DeltaN-PSGL-1 bound P-selectin, and trypsin treatment of the cells generated NH(2)-terminal monomeric fragments (<10 kDa) of PSGL-1 that bound to P-selectin. These results demonstrate that Cys(320)-dependent dimerization of PSGL-1 is not required for binding to P-selectin and that a small monomeric fragment of PSGL-1 is sufficient for P-selectin recognition.

Amino Acid Sequence↗
PubMed2000

Intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1, and regulated on activation normal T cell expressed and secreted are expressed by human breast carcinoma cells and support eosinophil adhesion and activation.

Eosinophils are usually associated with parasitic and allergic diseases; however, eosinophilia is also observed in several types of human tumors, including breast carcinomas. In this study we examined several human breast carcinoma cell lines for adhesion molecule expression and the ability to bind and activate eosinophils. MDA-MB-435S and MDA-MB-468 cells constitutively expressed both intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and this expression was enhanced by treatment with tumor necrosis factor-alpha (TNF-alpha). BT-20 and SK-BR-3 cells only expressed ICAM-1 or VCAM-1 after stimulation with TNF-alpha. Eosinophils constitutively bound to MDA-MB-435S cells, but not to BT-20 cells. Stimulation with TNF-alpha slightly enhanced eosinophil adhesion to MDA-MB-435S cells and dramatically increased adhesion to BT-20 cells. Greater than 80% of eosinophil adhesion to these cell lines was blocked with an anti-alpha4-integrin monoclonal antibody. Both MDA-MB-435S and BT-20 cells also released eosinophil activator(s). Supernatants from TNF-alpha-treated, but not control-treated, cell lines increased eosinophil adhesion to fibronectin and increased eosinophil transmigration across fibronectin-coated transwell plates. Enzyme-linked immunosorbent assays showed that TNF-alpha-stimulated breast carcinoma cells released the chemokine regulated on activation, T cell expressed and secreted (RANTES). Addition of an anti-RANTES antibody to breast carcinoma cell supernatants partially blocked eosinophil activation suggesting that RANTES in these supernatants was participating in eosinophil activation. These data show that TNF-alpha-stimulated breast carcinoma cells express mediators that can both bind and activate eosinophils, suggesting a mechanism for eosinophil localization to breast carcinoma sites.

Antigens, CD↗
PubMed1999

Mechanisms of selective leukocyte recruitment from whole blood on cytokine-activated endothelial cells under flow conditions.

Selective recruitment of eosinophils to sites of allergic and parasitic inflammation involves specific adhesion and activation signals expressed on or presented by stimulated endothelial cells. Here we examined leukocyte recruitment on cytokine-activated HUVEC under flow conditions. We perfused whole blood through a flow chamber to examine mechanisms of selective leukocyte recruitment. Although there was substantial recruitment of leukocytes on TNF-alpha-stimulated HUVEC, we found no selective accumulation of any particular leukocyte subpopulations. In contrast, fewer leukocytes were recruited to IL-4-stimulated HUVEC, but the recruitment was selective for eosinophils. We examined the role of adhesion molecules in these interactions and found that eosinophil recruitment was completely blocked with an alpha4 integrin mAb at the shear rates examined. A significant number of neutrophils were also recruited to IL-4-stimulated HUVEC, and these interactions required P-selectin and P-selectin glycoprotein ligand-1. Thus, whole blood perfusion over cytokine-activated endothelium revealed that IL-4-stimulated HUVEC support selective recruitment of eosinophils, whereas TNF-alpha-stimulated HUVEC lack selectivity for any leukocyte subclass.

Antigens, CD↗
PubMed1999

Ultrahigh-pressure reversed-phase capillary liquid chromatography: isocratic and gradient elution using columns packed with 1.0-micron particles.

Fused-silica capillaries with inner diameters of 33 microns and lengths of 25-50 cm are slurry-packed with 1.0-micron nonporous octadecylsilane-modified (C18) silica spheres. These columns are used to perform ultrahigh-pressure reversed-phase liquid chromatographic analyses in both isocratic and gradient elution modes. Mobile-phase pressures as high as 5000 bar (72,000 psi) are applied to column inlets to generate more than 200,000 theoretical plates in 6 min (k' approximately 1) for small, organic analytes. Average capacity factors of analytes are found to increase linearly with applied pressure. An electrically driven constant-flow syringe pump capable of generating mobile-phase pressures as high as 9000 bar (130,000 psi) is described. This pump is used in conjunction with an exponential dilution method for the gradient separation of peptides from a tryptic digest on a 27-cm-long capillary packed with 1.0-micron particles. A peak capacity of 300 is demonstrated for a 30-min analysis.

Chromatography, High Pressure Liquid↗
PubMed1998

Eosinophil tethering to interleukin-4-activated endothelial cells requires both P-selectin and vascular cell adhesion molecule-1.

We examined the mechanisms used by eosinophils to tether and accumulate on interleukin-4 (IL-4)-stimulated human umbilical vein endothelial cells (HUVECs) under flow conditions. As previously reported, HUVECs treated for 24 hours with 20 ng/mL IL-4 had increased expression of P-selectin and vascular cell adhesion molecule-1 (VCAM-1) but not E-selectin. We found that eosinophils tethered and rolled on IL-4-stimulated HUVECs at physiologic shear stresses. Eosinophil rolling was quickly followed by firm adhesion. Treatment with either an anti-P-selectin monoclonal antibody (MoAb) or an anti-VCAM-1 MoAb decreased both eosinophil tethering and accumulation at 2 dyn/cm2. VCAM-1 interacts with 4-integrins expressed on eosinophils. We found that an anti-4-integrin MoAb also blocked eosinophil tethering and accumulation at 2 dyn/cm2. None of these MoAbs alone had an impact on eosinophil accumulation at lower shear stresses, but when either an anti-VCAM-1 or an anti-4-integrin MoAb was used in combination with an anti-P-selectin MoAb, all eosinophil tethering and accumulation on IL-4-stimulated HUVECs were blocked. This was true at both high and low shear stresses. These data show that both P-selectin and VCAM-1 are required to tether eosinophils at high shear stresses, but at low shear stresses these adhesion proteins can act independently to recruit eosinophils to IL-4-stimulated HUVECs.

Antibodies, Monoclonal↗
PubMed1998

Characterization of Plasmodium falciparum-infected erythrocyte and P-selectin interaction under flow conditions.

Plasmodium falciparum-infected erythrocytes (IRBC) roll on the adhesion molecule P-selectin in vitro under flow conditions that approximate the shear stress in capillary and postcapillary venules in which cytoadherence occurs in vivo. The pathological significance of this adhesive interaction is currently unknown. In this study, we further investigated the molecular interactions between IRBC and P-selectin by using a laminar flow system that allowed for the direct visualization of IRBC-substratum interactions. The results showed that the IRBC-P-selectin interaction was Ca2+-dependent and involved the lectin domain of P-selectin and a sialic acid residue on IRBC. The sialylated P-selectin ligand was trypsin-sensitive, which suggests that it could be part of the parasite antigen PfEMP1 that interacts with CD36 and intercellular adhesion molecule-1 (ICAM-1), but different from a trypsin-resistant IRBC ligand that adheres selectively to chondroitin sulfate A. Studies on the rolling and adhesion of IRBC on activated platelets that express both CD36 and P-selectin showed that inhibition of rolling on P-selectin reduced the adhesion of some clinical parasite isolates to CD36, whereas other parasite isolates appeared to interact directly with CD36. Thus, cytoadherence under physiological flow conditions may be mediated by multiple IRBC ligands that interact with different adhesion molecules in a cooperative fashion. These findings underscore the complexity of the interactions betweeen IRBC and vascular endothelium.

Animals↗
PubMed1997

Comparison of tethering and rolling of eosinophils and neutrophils through selectins and P-selectin glycoprotein ligand-1.

We compared the abilities of selectins and the selectin ligand, P-selectin glycoprotein ligand-1 (PSGL-1), to support tethering and rolling of eosinophils and neutrophils under physiologic flow conditions. Eosinophils and neutrophils accumulated on P-selectin at similar site densities and rolled at similar velocities, but fewer eosinophils than neutrophils accumulated at any P-selectin density. Compared with neutrophils, few eosinophils accumulated on E-selectin except at high densities, and those cells that did accumulate rolled faster than neutrophils. Examination of the mechanisms for accumulation revealed that eosinophils and neutrophils formed similar numbers of primary tethers to P-selectin, whereas eosinophils formed fewer primary tethers to E-selectin than did neutrophils. Compared with neutrophils, adherent eosinophils also supported fewer leukocyte-leukocyte interactions, resulting in diminished secondary tethers to either P- or E-selectin. Studies with mAbs to L-selectin and PSGL-1 demonstrated that neither cell type used L-selectin to form primary tethers to P- or E-selectin. Both eosinophils and neutrophils used the NH2 terminus of PSGL-1 to form primary tethers to P-selectin, but not to E-selectin. Both cell types used L-selectin and PSGL-1 to promote leukocyte-leukocyte interactions and secondary tethers to P- or E-selectin. However, eosinophils developed significantly fewer secondary interactions, probably because they express less L-selectin than do neutrophils.

Cell Adhesion↗
PubMed1997

Soluble monomeric P-selectin containing only the lectin and epidermal growth factor domains binds to P-selectin glycoprotein ligand-1 on leukocytes.

Under shear stress, leukocytes use P-selectin glycoprotein ligand-1 (PSGL-1) to tether to and roll on P-selectin expressed on activated platelets or endothelial cells. P-selectin has an NH2-terminal lectin domain, an epidermal growth factor (EGF)-like motif, nine consensus repeats (CRs), a transmembrane domain, and a cytoplasmic tail. To determine whether the CRs are required for P-selectin to bind PSGL-1, we expressed a soluble protein (Lec-EGF) that contained only the lectin and EGF domains, plus a short C-terminal epitope tag. Electron microscopy and hydrodynamic analysis confirmed that Lec-EGF was monomeric, as previously shown for soluble P-selectin (sPS) that contained the lectin and EGF domains plus all nine CRs. Fluid-phase Lec-EGF or sPS inhibited binding of oligomeric125I-labeled membrane-derived P-selectin (mPS) to PSGL-1 on neutrophils and binding of 125I-PSGL-1 to immobilized mPS. The IC50 for inhibiting binding of mPS to neutrophils was fivefold greater for Lec-EGF than for sPS, whereas the IC50 for inhibiting binding of mPS to purified PSGL-1 was indistinguishable for Lec-EGF and sPS. Under static or shear conditions, neutrophils used PSGL-1 to tether to or roll on Lec-EGF that was captured by an immobilized monoclonal antibody to the C-terminal epitope. These data show that P-selectin requires only the lectin and EGF domains to bind to PSGL-1.

Cell Adhesion↗
PubMed1996

Interleukin 4 or oncostatin M induces a prolonged increase in P-selectin mRNA and protein in human endothelial cells.

During acute inflammation, P-selectin is transiently mobilized from Weibel-Palade bodies to the surface of histamine-activated endothelial cells, where it mediates rolling adhesion of neutrophils under hydrodynamic flow. During chronic or allergic inflammation, sustained expression of P-selectin on the endothelial cell surface has been observed. We found that the cytokines interleukin 4 (IL-4) or oncostatin M (OSM) induced a five- to ninefold increase in P-selectin messenger RNA (mRNA) in human umbilical vein endothelial cells (HUVEC) that persisted as long as 72 h. IL-4 elevated P-selectin mRNA by increasing its transcription rate rather than by prolonging its already long half-life. Stimulation of P-selectin transcription by IL-4 or OSM required new protein synthesis and tyrosine phosphorylation of cellular proteins. Tumor necrosis factor alpha, IL-1 beta, lipopolysaccharide, or IL-3 did not increase P-selectin mRNA in HUVEC, and did not augment the IL-4-induced increase in P-selectin transcripts. IL-4 or OSM increased P-selectin protein on the cell surface as well as in Weibel-Palade bodies. Under flow conditions, neutrophils rolled on P-selectin expressed by IL-4-treated HUVEC, and even more neutrophils rolled on P-selectin after IL-4-treated HUVEC were stimulated with histamine. These data demonstrate that IL-4 or OSM stimulates endothelial cells to synthesize more P-selectin over prolonged periods. The increased expression of P-selectin may facilitate the emigration of leukocytes into sites of chronic or allergic inflammation.

Animals↗
PubMed1996

Fine-needle aspiration cytology of sinus histiocytosis with massive lymphadenopathy: a case report.

Cytological findings of sinus histiocytosis with massive lymphadenopathy (SHML), involving bilateral cervical lymph nodes of a 12-yr-old boy, are presented here. A striking feature was the presence of large histiocytes with abundant pale cytoplasm containing well-preserved lymphocytes, plasma cells, and occasional neutrophils, scattered in a background of reactive lymphoid cells. Subsequent open biopsy of the lymph node mass confirmed the cytologic findings. Cytologic features of SHML are virtually diagnostic and can negate the need for an open biopsy in most cases.

Biopsy, Needle↗
PubMed1995

P-selectin glycoprotein ligand-1 mediates rolling of human neutrophils on P-selectin.

Neutrophils roll on P-selectin expressed by activated platelets or endothelial cells under the shear stresses in the microcirculation. P-selectin glycoprotein ligand-1 (PSGL-1) is a high affinity ligand for P-selectin on myeloid cells. However, it has not been demonstrated that PSGL-1 contributes to the rolling of neutrophils on P-selectin. We developed two IgG mAbs, PL1 and PL2, that appear to recognize protein-dependent epitopes on human PSGL-1. The mAbs bound to PSGL-1 on all leukocytes as well as on heterologous cells transfected with PSGL-1 cDNA. PL1, but not PL2, blocked binding of 125-I-PSGL-1 to immobilized P-selectin, binding of fluid-phase P-selectin to myeloid and lymphoid leukocytes, adhesion of neutrophils to immobilized P-selectin under static conditions, and rolling of neutrophils on P-selectin-expressing CHO cells under a range of shear stresses. PSGL-1 was localized to microvilli on neutrophils, a topography that may facilitate its adhesive function. These data indicate that (a) PSGL-1 accounts for the high affinity binding sites for P-selectin on leukocytes, and (b) PSGL-1 must interact with P-selectin in order for neutrophils to roll on P-selectin at physiological shear stresses.

Amino Acid Sequence↗
PubMed1995

P-selectin must extend a sufficient length from the plasma membrane to mediate rolling of neutrophils.

Under physiological shear stress, neutrophils roll on P-selectin on activated endothelial cells or platelets through interactions with P-selectin glycoprotein ligand-1 (PSGL-1). Both P-selectin and PSGL-1 are extended molecules. Human P-selectin contains an NH2-terminal lectin domain, an EGF domain, nine consensus repeats (CRs), a transmembrane domain, and a cytoplasmic tail. To determine whether the length of P-selectin affected its interactions with PSGL-1, we examined the adhesion of neutrophils to CHO cells expressing membrane-anchored P-selectin constructs in which various numbers of CRs were deleted. Under static conditions, neutrophils attached equivalently to wild-type P-selectin and to constructs containing from 2-6 CRs. Under shear stress, neutrophils attached equivalently to wild-type and 6 CR P-selectin and nearly as well to 5 CR P-selectin. However, fewer neutrophils attached to the 4 CR construct, and those that did attach rolled faster and were more readily detached by increasing shear stress. Flowing neutrophils failed to attach to the 3 CR and 2 CR constructs. Neutrophils attached and rolled more efficiently on 4 CR P-selectin expressed on glycosylation-defective Lec8 CHO cells, which have less glycocalyx. We conclude that P-selectin must project its lectin domain well above the membrane to mediate optimal attachment of neutrophils under shear forces. The length of P-selectin may: (a) facilitate interactions with PSGL-1 on flowing neutrophils, and (b) increase the intermembrane distance where specific bonds form, minimizing contacts between the glycocalyces that result in cell-cell repulsion.

Animals↗
PubMed1995

Neutrophils use both shared and distinct mechanisms to adhere to selectins under static and flow conditions.

Both P-selectin glycoprotein ligand-1 (PSGL-1) and L-selectin are localized on the microvilli of neutrophils and have been implicated in the attachment of neutrophils to P-selectin or E-selectin. We directly compared the attachment and rolling of neutrophils on P-selectin and E-selectin under flow, with emphasis on the functions of PSGL-1 and L-selectin. Flowing neutrophils attached more avidly and rolled at lower velocities on P-selectin than on E-selectin at matched densities. Studies with purified molecules indicated that P-selectin and E-selectin bound to a related site on PSGL-1 that overlapped the epitope for the anti-PSGL-1 mAb PL1. E-selectin bound with lower affinity than P-selectin to this site and also bound to an additional site(s) on PSGL-1.PL1 abolished adhesion of neutrophils to P-selectin under shear or static conditions, whereas DREG-56, a mAb to L-selectin, had no effect on adhesion to P-selectin. PL1 inhibited attachment of neutrophils to E-selectin under flow but not static conditions. DREG-56 also inhibited attachment of flowing neutrophils to E-selectin, and a combination of DREG-56 and PL1 nearly eliminated attachment to E-selectin under flow. These data suggest that PSGL-1 functions cooperatively with L-selectin to mediate optimal attachment of flowing neutrophils to E-selectin but not to P-selectin. Neutrophils attach more efficiently and with greater strength to P-selectin, perhaps because of the higher affinity of P-selectin for the PL1-defined site on PSGL-1.

Animals↗