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Biomedical subjects

C R Parish

Publications and source records attributed to C R Parish.

At least 55 records · Page 3Linked to original sources
PubMed1994

Mac-1 (CD11b/CD18) and CD45 mediate the adhesion of hematopoietic progenitor cells to stromal cell elements via recognition of stromal heparan sulfate.

Hematopoiesis is regulated by two sets of signals, those generated by cytokines and those generated when precursor cells interact with bone marrow (BM) stroma. The intimate contact between precursors and stroma appears to be mediated by multiple, different receptor-ligand binding events. To identify receptor-ligand pairs mediating the adhesion of hematopoietic precursor cells to stroma, an in vitro model of hematopoiesis was used. This involved coculturing the BM-derived, interleukin-3 (IL-3)-dependent, multipotential cells, FCDP-mix A4 (A4) with a stromal equivalent embryonic mesenchymal cell line, Swiss 3T3 (3T3). In coculture, A4 cells survive, proliferate, and differentiate in the absence of exogenous IL-3, providing they are attached to the 3T3 cell surface. By using detergent lysates of surface-biotinylated A4 cells, A4 cell molecules that bind to the stroma could be detected by either fluorescein isothiocyanate (FITC)-streptavidin or FITC-antibody staining and flow cytometry. Using this approach the beta 2 integrin, Mac-1, and CD45, a receptor-type tyrosine phosphatase, were identified as molecules on the A4 cell surface that bind 3T3 cells. Various glycosaminoglycans (GAGs), particularly heparin and heparan sulfate, blocked binding of A4 cell surface molecules to the 3T3 cells. The binding of CD45 and Mac-1 to the 3T3 cells was similarly blocked by these GAGs. Removal of heparin-binding molecules from A4 cell lysates diminished binding to the 3T3 cells and digestion of the 3T3 cell surface with heparinase abolished the binding of CD45 and Mac-1. The data suggest that heparan sulfate on the 3T3 cell surface is a ligand for both CD45 and Mac-1, but the two molecules recognize different heparan sulfate structural motifs.

3T3 Cells↗
PubMed1994

Anti-HIV-1 activity of chemically modified heparins: correlation between binding to the V3 loop of gp120 and inhibition of cellular HIV-1 infection in vitro.

Chemically modified heparins were tested for their activities in (i) inhibiting HIV-1 replication in vitro and (ii) inhibiting the binding to recombinant HIV-1 gp120 of monoclonal antibodies specific for the V3 loop. The results reveal that N-desulfation reduces activity, although this is largely restored on N-acetylation. Selective O-desulfation also markedly reduces activity, whereas carboxyl reduction has little effect. Overall these results show that the anti-HIV-1 activity of heparin does not depend simply on negative density, and indicate instead that particular structures, notably O-sulfates, are involved. Our studies reveal that for chemically modified heparins and heparin-derived fragments there is a striking correlation between anti-HIV-1 activity in vitro and binding to the V3 loop of gp120 in solid phase ELISA. This strongly suggests that the heparin exerts its anti-HIV-1 activity by binding to the V3 loop of gp120.

Acetylation↗
PubMed1994

Determination of lymphocyte division by flow cytometry.

Techniques currently available for determining cell division are able to show one or, at best, a limited number of cell divisions. Other methods exist which can quantify overall division, but tell nothing about the division history of individual cells. Here we present a new technique in which an intracellular fluorescent label is divided equally between daughter cells upon cell division. The technique is applicable to in vitro cell division, as well as in vivo division of adoptively transferred cells, and can resolve multiple successive generations using flow cytometry. The label is fluorescein derived, allowing monoclonal antibodies conjugated to phycoerythrin or other compatible fluorochromes to be used to immunophenotype the dividing cells.

Animals↗
PubMed1994

Evidence for cell surface association of CD2 and LFA-1 (CD11a/CD18) on T lymphocytes.

Previous studies have reported an association of the cell surface adhesion molecule CD2 with the T cell receptor and with CD45 on mouse and human T lymphocytes. In this study the association of CD2 with cell surface molecules was investigated using cell surface biotinylation of T lymphocytes, coupled with immunoprecipitation using two CD2-specific monoclonal antibodies (mAb) (RM2-5 and 12-15) and analysis by SDS-PAGE. Although both CD2 mAb immunoprecipitated CD2 from lysates of murine lymphocytes, it was found that mAb 12-15, but not RM2-5, co-precipitated two other molecules of 95 and 180 kDa. Subsequent studies revealed that the 95- and 180-kDa molecules were associated with a subspecies of CD2 (approximately 5%) on thymocytes, the antigen-specific T cell line D10, and splenic T cells but not B cells. Two lines of evidence were obtained consistent with the 95- and 180-kDa molecules being the beta and alpha chains of LFA-1. Firstly, an analysis of 12-15 mAb immunoprecipitates on 4-12% gels under reducing and nonreducing conditions shows that the 95- and 180-kDa molecules have a molecular weight and migration pattern identical to LFA-1. Secondly, depletion of LFA-1 from lysates with LFA-1 mAb abolished the ability of CD2 mAb 12-15 to co-precipitate the 95- and 180-kDa molecules, thereby identifying these as the beta and alpha chains of mouse LFA-1, respectively. These results provide evidence for the first time for an association of LFA-1 and CD2 on mouse T lymphocytes, and suggest that the association occurs with an immunologically distinct subspecies of CD2 molecules.

Animals↗
PubMed1994

Effects of the anti-inflammatory compounds castanospermine, mannose-6-phosphate and fucoidan on allograft rejection and elicited peritoneal exudates.

The glycoprotein processing inhibitor castanospermine (CS) and the monosaccharide mannose-6-phosphate (M6P), as well as some sulfated polysaccharides (SPS), have been shown to inhibit inflammation in rat models of experimental autoimmune encephalomyelitis and adjuvant-induced arthritis. Here, the anti-inflammatory effects of these agents have been further explored in murine models of allograft rejection and elicitation of peritoneal exudates. CS, M6P and the SPS, fucoidan, partially inhibited rejection of permanently accepted thyroid allografts induced by the i.p. injection of donor strain (H-2d) spleen cells with a reduction in leucocyte infiltration of 25-36%. However none of these agents reduced the more extensive leucocyte infiltration induced by the i.p. injection of P815 (H-2d) unless recipient mice were pretreated with the immunosuppressant, cyclosporin A (CsA). Elicitation of peritoneal exudates by thioglycollate was inhibited by CS, M6P and fucoidan with sustained leucopenia being induced by CS. In contrast, CS and fucoidan, but not M6P, inhibited antigen-elicited peritoneal exudates. These results suggest that CS, M6P and the SPS fucoidan exhibit subtle differences in their anti-inflammatory activity but probably inhibit inflammation at the level of leucocyte extravasation.

Animals↗
PubMed1994

Evidence for an association of CD45 with 32,000-33,000 MW phosphoproteins on murine T and B lymphocytes.

In human T cells CD45 is reported to associate with both cell surface and intracellular molecules including CD2, CD4/CD8, CD5, p56lck and p59fyn. In this study the association of molecules with CD45 in murine T lymphocytes was explored using biotinylation, chemical cross-linking, immunoprecipitation and 32P-labelling. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of CD45 monoclonal antibody (mAb) (S-450-15.2) immunoprecipitates from Triton X-100 lysates of murine thymocytes that were surface biotinylated and treated with the chemical cross-linker 3,3'-dithio-bis(sulpho-succinimidylpropionate) (DTSSP) showed that CD45 can be chemically linked to molecules of 25,000-32,000, 42,000 and 60,000-70,000 MW. The CD45 mAb also co-precipitated a prominent 32,000 MW molecule from digitonin lysates of surface biotinylated murine thymocytes, splenocytes and D10 cells, but a weaker association was also detected on splenic B cells and on the murine B-cell lymphoma line A20. The results suggest that in these cells CD45 is associated with a 32,000 MW molecule which is exposed extracellularly. Experiments in which thymocytes were biotinylated after permeabilization with lysolecithin showed that additional molecules of 33,000, 55,000, 60,000 and 90,000 MW, presumably localized intracellularly, also co-precipitated with CD45. Labelling of murine thymocytes or D10 cells with H3(32)PO4 in vivo, and of CD45 immunoprecipitates by in vitro kinase reaction, revealed that the 32,000-33,000 MW molecules are phosphoproteins. The relationship of these molecules with the 30,000-34,000 MW molecules previously reported to associate with CD45 in human T cells is not clear as a number of differences were observed. Firstly, the molecular weight of the CD45-associated 32,000-33,000 MW molecule(s) on murine T cells and B cells is slightly lower than that observed in the human T-cell line Jurkat (34,000 MW). Secondly, phosphoamino acid analysis after in vitro kinase labelling of CD45 immunoprecipitates showed that the murine 32,000-33,000 MW molecules are phosphorylated exclusively on serines. Thirdly, although in vitro phosphorylation of the 32,000-33,000 MW molecules was inhibited by preincubation with either GTP-gamma-S or GDP-beta-S, the 32,000-33,000 MW CD45-associated molecules did not bind 32P-GTP, GDP-agarose, or react with antisera to a consensus sequence of G proteins. The crucial role of CD45 for proper function of the T-cell receptor (TCR), suggests that the CD45-associated 32,000-33,000 MW molecules and kinases also may play a role in the signalling events leading to T-cell activation.

Animals↗
PubMed1993

CD48 is a low affinity ligand for human CD2.

COS cells transiently transfected with human CD48 were found to bind human PBL, whereas mock or CD7-transfected COS cells failed to bind human lymphocytes. Binding of PBL to CD48 transfectants was almost totally inhibited by either CD48 mAb pretreatment of COS cells or CD2 mAb pretreatment of PBL, implying an interaction between CD2 and CD48. This conclusion was confirmed by the demonstration that a highly fluorescent, multimeric form of rCD2 bound to CD48 transfected COS cells in a CD48-dependent manner. Additional mAb blocking studies revealed that CD48 interacts with the T11(1) region of CD2, the same region of CD2 that binds LFA-3 (CD58). Thus, CD48 and CD58 represent alternative and possibly competing ligands for CD2, although based on blocking studies with soluble CD2, CD48 interacts with CD2 with approximately a 100-fold lower affinity that CD58.

Antibodies, Monoclonal↗
PubMed1993

Detection of a glycosylation-dependent ligand for the T lymphocyte cell adhesion molecule CD2 using a novel multimeric recombinant CD2-binding assay.

The CD2 molecule plays an important role in T cell adhesion by interacting with the ligands CD58 (LFA-3) and CD59. In order to detect additional ligands for CD2, potentially of low binding affinity, we have prepared a highly fluorescent, multimeric form of rCD2 whose binding to cells can be quantified by flow cytometry. Initial studies demonstrated that binding of multimeric rCD2 to cells was CD2-specific, concentration and time dependent, and saturable. The negative charge on cells was also found to play a critical role in the efficiency of multimeric rCD2 binding. Analysis of binding of multimeric rCD2 to 17 CD58+ cell types revealed that only 8 of the cells exhibited binding. Failure of multimeric rCD2 to interact with the other cells could not be explained by differences in CD58 expression, suggesting that, in terms of CD2 binding, there are qualitative differences in CD58 on different cell types. Binding of multimeric rCD2 to six of the seven reactive cells was virtually totally inhibited by CD58 mAb pretreatment, whereas binding to the erythroleukemic line K562 was only partially blocked, suggesting the existence of another CD2 ligand. Subsequent studies demonstrated that the putative new ligand is not CD59, and that it interacts with a different region of the CD2 molecule than CD58, probably a site located between the T11(1) and T11(2) epitopes. The binding affinity of CD2 for the new ligand is 10-fold lower than for CD58 and, based on studies with truncated rCD2, the binding site for the new ligand is located within the amino-terminal 105 amino acids of the CD2 polypeptide. Unlike CD58, the new ligand is tunicamycin sensitive suggesting that it contains a N-linked carbohydrate structure that is essential for functional activity.

Antibodies, Monoclonal↗
PubMed1993

Investigation of the ability of several naturally occurring and synthetic polyanions to bind to and potentiate the biological activity of acidic fibroblast growth factor.

The ability of several animal, plant, and bacterial derived polyanions (PAs) as well as synthetic PAs to compete with heparin for the binding of acidic fibroblast growth factor (aFGF) was correlated with their ability to potentiate the mitogenic and neurotrophic actions of this factor. Dextran sulphate, kappa-carrageenan, pentosan sulphate, polyanethole sulfonate, heparin, and fucoidin competed for the heparin binding site on aFGF at relatively low concentrations (< 50 micrograms/ml). lambda-carrageenan, iota-carrageenan, and polyvinyl sulphate exhibited lower affinity for aFGF, whereas hyaluronic acid, dermatan sulphate, chondroitin-6-sulphate, chondroitin-4-sulphate, and uncharged dextran displayed very low or no demonstrable affinity. Potentiation of the mitogenic action of aFGF for Balb/c 3T3 fibroblasts tended to be in general agreement with the aFGF binding affinity of the PAs. However, polyanethole sulfonate, the carrageenans, polyvinyl sulphate, fucoidin, and pentosan sulphate exerted a mitogenic action on the 3T3 cells that was independent of, and in addition to, the ability of these GAGs to potentiate the action of aFGF. The ability to potentiate the neurotrophic action of aFGF for E8 chick ciliary neurons was a general property of those PA with low or no activity in the mitogen assay. Thus hyaluronic acid, dermatan sulphate, chondroitin-4-sulphate, chondroitin-6-sulphate, and even unchanged dextran all potentiated aFGF induced neuronal survival. The differential effects of these PA in potentiating the biological activities of aFGF are discussed in relation to their ability to compete for the heparin-binding site of aFGF.

3T3 Cells↗
PubMed1993

Polysaccharides influence the aggregation of Dictyostelium discoideum cells and bind to developmentally regulated cell surface proteins.

Six of ten anionic polysaccharides studied were found to significantly reduce the adhesion of growth-phase Dictyostelium discoideum cells. However, only hyaluronic acid, chondroitin-4-sulfate and chondroitin-6-sulfate interfered with the adhesion of aggregation-competent cells. Neither EDTA-stable nor EDTA-sensitive adhesion of postaggregation cells were affected by the polyanions. The two chondroitin sulfates influenced the aggregation of cells in submerged cultures, long and broad aggregation streams being formed and the broad sheets of cells eventually building multilayered aggregates. Radioiodination of cell surface proteins followed by cellulose fiber affinity chromatography identified the same nine proteins bound by hyaluronic acid and the chondroitin sulfates, six of which were regulated during development. Protease-resistant anionic material isolated from cells bound the same surface proteins as the three glycosaminoglycans. Discoidin I bound to the uncoupled cellulose fibers, suggesting a structural role for the lectin in the extracellular slime sheath. Anionic polysaccharides and cell surface lectins that bind them may be involved in the cell recognition, cell aggregation, and the cell sorting that occurs during pattern formation.

Animals↗
PubMed1992

A basement-membrane permeability assay which correlates with the metastatic potential of tumour cells.

We describe an in vitro assay for measuring the ability of tumour cells to permeabilize basement membranes, using transwell chambers coated with the reconstituted basement membrane, matrigel. Unlike previous matrigel-based procedures which quantified passage of tumour cells across a matrigel barrier, the new assay measures the ability of tumour cells to degrade the basement membrane and increase the diffusion rate of fluorescent (FL) dextran through the barrier. The procedure has the major advantage that permeability can be rapidly and accurately quantified, either by fluorometry or by the use of radiolabelled dextran, thus avoiding tedious and subjective scoring methods. Optimal conditions for the assay are described. In addition, it is demonstrated that the assay can clearly discriminate between metastatic and non-metastatic tumour cell lines, metastatic tumours permeabilizing the basement membrane and non-metastatic counterparts failing to do so. A range of enzyme inhibitors suggested that the increase in basement-membrane permeability caused by the metastatic mammary adenocarcinoma 13762 MAT is probably dependent upon the synergistic action of several degradative enzymes, namely proteases, type-IV collagenase, and heparanase. Furthermore, the ability to permeabilize the basement membrane was dependent upon intact tumour cells; tumour cell extracts, lysates and supernatants were inactive.

Animals↗
PubMed1992

Ability of different chemically modified heparins to potentiate the biological activity of heparin-binding growth factor 1: lack of correlation with growth factor binding.

A range of chemically modified heparins was examined for their ability to bind heparin-binding growth factor 1 (HBGF-1; acidic fibroblast growth factor) and potentiate the in vitro mitogenic and neurotrophic activity of HBGF-1. It was found that carboxyl-reduced heparin bound HBGF-1 as effectively as the native heparin molecule. Totally desulfated heparin and N-desulfated heparin lack HBGF-1-binding capacity, and substitution of the exposed amino group with acetyl or acetoacetyl groups only partially restored binding capacity, indicating that N-sulfates only play a limited role in growth factor binding. However, the failure of totally desulfated, N-resulfated heparin to interact with HBGF-1 demonstrated that N-sulfates alone are insufficient and ester sulfates are absolutely essential for HBGF-1 binding. In contrast, the ability of the modified heparins to potentiate the mitogenic activity of HBGF-1 correlated only to a limited extent with their affinity for HBGF-1. Thus, the carboxyl-reduced molecule which displayed similar affinity for HBGF-1 as native heparin was consistently less potent in augmenting mitogenesis. Similarly, the N-acetylated and the N-acetoacetylated species, which had much lower affinity for HBGF-1 than the carboxyl-reduced molecule, conferred similar biological activity to HBGF-1 whereas N-desulfated heparin, which was unable to bind growth factor, potentiated the mitogenic activity of HBGF-1 for both 3T3 and HUVE cells. In contrast, the neurotrophic activity of HBGF-1 was potentiated by modified heparin species which failed to bind HBGF-1 and were without activity in the mitogenic assays.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1992

Calcein: a novel marker for lymphocytes which enter lymph nodes.

Previous studies have identified unique cell surface antigens which are associated with the specific binding of lymphocytes to high endothelial venules (HEV). Evidence is presented in this paper which demonstrates that uptake of the fluorescent dye calcein by lymphocytes represents an additional marker for the lymph node homing subpopulation of lymphocytes. Calcein exhibits a characteristic ability to label lymphocytes differentially into two distinct populations, based on fluorescence intensity, that does not occur with three other structurally related, fluorescein-based dyes. In vivo lymphocyte migration studies revealed that cells displaying the "dull" fluorescence phenotype, although entering all lymphoid organs examined, preferentially homed to the lymph nodes, particularly the popliteal lymph node (PLN). By contrast, lymphocytes displaying the "bright" phenotype were essentially excluded from entering lymphoid organs, where entry is HEV dependent, but were observed entering spleen, where entry is HEV independent. Furthermore, a high proportion (76.5%) of lymphocytes displaying the dull fluorescence phenotype expressed the PLN homing receptor MEL-14. Based on these observations it is suggested that calcein uptake may be a marker for general membrane properties, such as fluidity and plasticity, essential for the passage of lymphocytes through HEV.

Animals↗
PubMed1992

Evidence that mannose recognition by splenic sinusoidal cells plays a role in the splenic entry of lymphocytes.

Previous studies demonstrated that mannan is a potent inhibitor of splenic entry of lymphocytes and mediates its inhibitory effect at an unidentified site in the spleen rather than acting directly on lymphocytes. This report describes the in vivo site of action of mannan. In vivo localization studies with fluoresceinated preparations of mannan (Fl-mannan) and a mannose-6-phosphate-containing yeast phosphomannan monoester core from P. holstii exopolysaccharide (Fl-PPME) demonstrated that the polysaccharide specifically localize in the splenic marginal sinuses in cells with a dendritic morphology termed splenic sinusoidal cells (SSC). Uptake of the polysaccharides by SSC was mediated by a mannan-specific receptor which was saturable and of high avidity. Several lines of evidence suggested that mannan uptake by SSC inhibited splenic entry of lymphocytes. First, the ability of SSC to bind Fl-mannan and Fl-PPME closely paralleled the ability of these polysaccharides to inhibit splenic entry of lymphocytes. In fact, doses of mannan and PPME which would saturate SSC mannan receptors completely blocked splenic entry of lymphocytes. Second, SSC are situated at the initial entry point of lymphocytes into spleen and passage of lymphocytes through the SSC region of spleen was profoundly inhibited by mannan. Finally, direct evidence for adhesion between lymphocytes and SSC was obtained with spleen cell suspensions where clustering between Fl-mannan labeled SSC and lymphocytes was observed. Collectively, these data indicate that mannan (and PPME) inhibit splenic entry of lymphocytes by interacting with SSC, cell which play a critical role in the entry of lymphocytes into the spleen. Whether mannan-specific receptors on SSC directly mediate lymphocyte-SSC adhesion or play on indirect role in modifying lymphocyte migration requires further investigation.

Animals↗
PubMed1992

Selective localisation of neuro-specific T lymphocytes in the central nervous system.

Using experimental autoimmune encephalomyelitis (EAE) in the rat as a model of central nervous system (CNS) inflammation, activated and quiescent T lymphocytes with different antigen specificities were labelled with the fluorescent dye Hoechst 33342 and tested by fluorescence microscopy for their ability to accumulate in different regions of the spinal cord and in other organs at varying times post inoculation. With this highly sensitive assay it was found that activated myelin basic protein (MBP)-specific T cell lines accumulated in the spinal cord (a 1000-fold increase in the lumbar/sacral region by day 4) and caused clinical signs of EAE. In contrast, interleukin-2 (IL-2)-maintained (quiescent) MBP-specific T cell lines failed to accumulate in the CNS and cause disease. Activated ovalbumin (OA)-specific and purified protein derivative of tuberculin (PPD)-specific T cell lines were also found at significantly higher levels in the spinal cord than non-activated cells although they failed to accumulate to a substantial degree when injected alone. When injected with activated MBP-specific T cells the activated OA- and PPD-specific cell lines accumulated in the spinal cord following initial accumulation of the MBP-specific cells, demonstrating that during the inflammatory process there is considerable non-specific recruitment of cells into the inflammatory site. CNS accumulation of activated MBP-specific T cell lines occurred 1-2 days later in irradiated animals than in non-irradiated recipients. This was consistent with irradiated animals also exhibiting a later onset of disease and suggests that irradiation may directly affect the endothelium in a way that makes it less adhesive. In conclusion, this study demonstrates that activated lymphocytes of any specificity enter the spinal cord, and that the neuro-antigen specific cells accumulate there and lead to the recruitment of other cells. Non-activated cells, even those with neural antigen specificity fail to enter the cord. Understanding the nature of what an 'activated' lymphocyte is may allow us to design strategies to inhibit such immune-mediated inflammation.

Animals↗
PubMed1992

Inhibition of adjuvant arthritis in the rat by phosphosugars and the alpha-glucosidase inhibitor castanospermine.

The development of joint inflammation of adoptively transferred arthritis in rats was inhibited by treatment with the simple sugar mannose-6-phosphate or the alkaloid inhibitor of alpha-glucosidase, castanospermine. Mannose-6-phosphate was effective at a dose of 25 mg/kg per day delivered via mini-osmotic pumps implanted either subcutaneously or intraperitoneally. Castanospermine was given orally in the drinking water and rats ingested on average 60-65 mg/kg per day. Histological examination of tissue from treated rats revealed greatly reduced inflammatory infiltrates into the synovium and surrounding tissue. Castanospermine not only inhibited the development of arthritis but also inhibited the progression of the disease when treatment was commenced after the onset of symptoms. Possible mechanism(s) of action of these compounds could be their ability to inhibit the passage of leucocytes through vascular subendothelial basement membranes by inhibiting the function or expression of leucocyte cell surface-bound enzymes that are essential for such migration. Castanospermine could also inhibit inflammation through its ability to prevent the expression of adhesion molecules, which may be necessary for the capture and retention of leucocytes in the inflamed tissue.

Animals↗
PubMed1991

Modification of lymphocyte migration by mannans and phosphomannans. Different carbohydrate structures control entry of lymphocytes into spleen and lymph nodes.

Previous in vitro studies suggest that recognition of phosphomannosyl structures by lymphocytes plays a central role in the binding of lymphocytes to high endothelial venules. However, the physiologic relevance of phosphomannosyl recognition in in vivo lymphocyte migration has not been established. This paper describes experiments that examined this question. It was demonstrated that the phosphomannan monoester core (PPME) from Pichia holstii, a potent inhibitor of peripheral node high endothelial venule interactions in vitro, was a very effective inhibitor of in vivo lymphocyte migration, as little as 39 micrograms/mouse significantly inhibiting popliteal lymph node entry. Furthermore, PPME exhibited a similar hierarchy of inhibition in vivo as previously reported in vitro, most effectively inhibiting entry of lymphocytes into popliteal lymph node, somewhat less effectively inhibiting mesenteric lymph node entry and being a relatively poor inhibitor of Peyer's patch entry. Additionally, PPME inhibited splenic entry of lymphocytes, and inhibition of lymphoid organ entry was accompanied by a substantial leukocytosis. Two additional mannose-containing compounds were found to modify lymphocyte migration, namely a well defined mannose containing pentasaccharide (PENT) with terminal mannose-6-phosphate (M6P) and an unphosphorylated yeast mannan. Both PENT and mannan induced leukocytosis and were particularly effective at inhibiting splenic entry of lymphocytes. In fact, detailed dose-response curves indicated that mannan was a much more potent inhibitor of splenic entry than PPME or PENT, whereas in lymph nodes PPME was the most effective inhibitor. Pretreatment of lymphocytes before injection with either PPME or mannan demonstrated that PPME could act at the lymphocyte level, whereas mannan probably acted at some other site. Collectively, these data suggest that different carbohydrate structures are involved in the entry of lymphocytes into different lymphoid organs, with mannose recognition playing an important role in splenic entry and recognition of M6P-like structures controlling lymph node entry. In contrast, it was found that mannose-and M6P-containing structures, unlike sulfated polysaccharides such as fucoidan, did not affect the subsequent positioning of lymphocytes within lymphoid organs.

Animals↗