The role of natural killer T (NKT) cells in immune thrombocytopenia: is strong in vitro NKT cell activity related to the development of remission?
Explore the source record for details and available documents.
Aged↗
Biomedical subjects
M G Macey
Publications and source records attributed to M G Macey.
Effect on polymorphonuclear cell function of a human-specific cytotoxin, intermedilysin, expressed by Streptococcus intermedius.
Streptococcus intermedius is a member of the normal flora of the mouth but is also an opportunistic pathogen associated with purulent infections at oral and nonoral sites. Intermedilysin (ILY) has been shown to be a cytolysin capable of generating pores in the cell membrane of erythrocytes demonstrable by electron microscopy. This effect has been shown to be specific for human cells. Since polymorphonuclear cells (PMNs) are the main cell involved in innate immunity we investigated the effect of purified intermedilysin from Streptococcus intermedius on PMN function. Active ILY at a concentration of 40 ng/microl caused a significant decrease in the number of intact PMNs after 60 min. The active cytolysin, when compared with heat-inactivated ILY, did not appear to be chemotactic for the PMNs but did cause an increase in intracellular calcium, with increased cell surface CD11b expression, metabolic burst, and phagocytosis of Staphylococcus aureus. These findings may have implications for the role of ILY in deep-seated abscesses.
Bacterial Proteins↗
Leucodepletion and the interaction of polymorphonuclear cells with endothelium in systemic inflammatory response syndrome.
The abnormal interaction of polymorphonuclear cells (PMNs) with blood vessel walls is considered to underlie the multiple organ failure of systemic inflammatory response syndrome (SIRS). This consideration is supported by the present finding that PMNs from patients with SIRS are activated, as assessed by an increased distribution of cells bearing CD64, enhanced expression of CD11b and decreased expression of CD62L, and are highly adhesive to endothelial monolayers. Passage of SIRS blood through leucodepletion filters in a laboratory-designed extracorporeal circuit resulted in a marked depletion of PMNs. Of the PMNs that remained in the blood, far fewer cells bound to cultured endothelial cells in comparison with PMNs prior to leucofiltration. We propose that leucofiltration of SIRS blood will limit the number of PMNs available for binding to blood vessel walls and, hence, reduce the pathological manifestations associated with this disorder.
Case-Control Studies↗
Flow cytometric analysis of different adhesion molecules expression on circulating CD14- and CD64- human dendritic cell precursors.
Blood dendritic cell precursors (DCps) are identified as mononuclear leukocytes expressing HLA-DR but lacking the characteristic antigens associated with T cells (CD3), NK cells (CD16 and CD56) and B cells (CD 19). Dendritic cell precursors are distinguished from monocytes by their lack of expression of CD64 rather than of CD14. This study investigated whether CD14- DCps differed from CD64-DCps, which were predominantly CD14+, in their expression of five well-characterised adhesion molecules. There were significantly fewer cells expressing CD11b, CD18 and CD29 in the CD64-DCp population compared with CD14- DCps, and this CD64- DCp subpopulation also had a lower expression of CD11b and CD18. Our results suggest that the two DC precursor subpopulations may differ from one another in their binding characteristics to blood vessel walls and to other leukocytes.
Antigens, CD↗
Use of mean platelet component to measure platelet activation on the ADVIA 120 haematology system.
Platelet activation results in changes in a number of cell surface molecules including an increase in P-Selectin (CD62P) that may be rapidly and conveniently measured by immunofluorescent flow cytometry. The ADVIA 120 (Bayer) is a new system that facilitates more accurate measurement of platelet volume and in addition provides an approximate measure of the mean refractive index (RI) of the platelets reported as mean platelet component (MPC) concentration. We were interested to determine whether changes in MPC might reflect changes in platelet activation status. To investigate this, the platelet CD62P expression, determined by flow cytometry, and change in MPC, measured on the ADVIA 120 system, was first examined in vitro after stimulation of EDTA anticoagulated whole blood with submaximal concentrations of bovine thrombin in the presence or absence of the thromboxane synthase inhibitor, Ridogrel. Thrombin produced a dose-dependent increase in platelet CD62P expression and a decrease in MPC that could be inhibited by Ridogrel at physiological concentrations. In the second set of experiments, blood from 20 normal controls was collected into both EDTA and sodium citrate (SC) anticoagulants. Within 30 min of venesection and again at 3 h post-venesection after storage at room temperature, the platelet MPC and CD62P expression were determined. Platelets in all samples with both anticoagulants showed very low levels of CD62P expression when first analysed. At 3 h there was a small increase in CD62P expression on platelets in whole blood anticoagulated with SC, but a significant (P < 0.001) increase was observed on platelets anti-coagulated with EDTA. A negative correlation was found between the change in MPC of the platelets and the increase in the mean fluorescence intensity (MFI) (r = -0.69, P < 0.001, n = 20) and the percentage (r = -0.72, P < 0.001, n = 20) of CD62P positive platelets at 3 h in blood anticoagulated with EDTA. We conclude that a reduction in MPC as measured by the ADVIA 120 may be used to detect anticoagulant induced, as well as thrombin stimulated, in vitro platelet activation in blood anticoagulated with EDTA. Further, we conclude that platelet activation is negligible for up to 3 h in sodium citrate anticoagulated whole blood.
Adult↗
Comparative study of five commercial reagents for preparing normal and leukaemic lymphocytes for immunophenotypic analysis by flow cytometry.
The flow cytometric analysis of leucocytes in whole blood is usually performed on samples in which the erythrocytes have been lysed and the leucocytes fixed. Because lysis and fixation reagents have the potential to introduce artefacts, several commercially available reagents were used to prepare normal and leukaemic lymphocytes for immunophenotypic analysis by flow cytometry, and the results were compared with those obtained from live whole blood. The reagents tested were the ImmunoPrep system and OptiLyse C (Coulter), LF-1000-Lyse and Flow (Harlan), Uti-Lyse (Dako) and FACS Lysing Solution (Becton Dickinson). The effect of each reagent on the apparent expression of CD3, CD5, CD11b, CD45, FMC7, kappa and lambda antigens was determined on lymphocytes from six normal controls and from six patients with chronic lymphocytic leukaemia (CLL). The following observations were made: (i) the time in minutes for each procedure varied markedly and was 1.5, 15, 20, 30 and 30 for the ImmunoPrep system, OptiLyse C, Uti-Lyse, FACS Lysing Solution, and LF-1000, respectively, but only 0.5 min for live whole blood. (ii) The forward and side scatter characteristics were affected by all of the lysis and fixation procedures, and this was most marked for LF-1000-Lyse and Flow. (iii) OptiLyse C gave preparations with poor forward and side scatter resolution due to the presence of residual red cell fragments. (iv) Lysis and fixation procedures did not affect the apparent expression of the CD3, CD45, or FMC7 antigens on normal or CLL samples, but gave highly variable results for the expression of the CD5, CD11b, kappa, and lambda antigens on the CLL samples. We conclude that lysis and fixation procedures can introduce different artefacts in the analysis of normal and leukaemic samples that are best avoided by analysing live whole blood.
Aged↗
Subcellular distribution and redistribution of Bcl-2 family proteins in human leukemia cells undergoing apoptosis.
It has been suggested that the ratio of Bcl-2 family proapoptotic proteins to antiapoptotic proteins determines the sensitivity of leukemic cells to apoptosis. However, it is believed that Bcl-2 family proteins exert their function on apoptosis only when they target to the mitochondrial outer membrane. The vinblastine-resistant T-lymphoblastic leukemic cell line CEM/VLB100 has increased sensitivity to tumor necrosis factor-alpha (TNF-alpha)-induced cytochrome c release, mitochondrial respiratory inhibition, and consequently apoptosis, compared with parental CEM cells. However, there was no difference between the two cell lines in the expression of Bcl-2 family proteins Bcl-2, Bcl-XL, Bcl-XS, Bad, and Bax at the whole cell level, as analyzed by Western blotting. Bcl-2 mainly located to mitochondria and light membrane as a membrane-bound protein, whereas Bcl-XL was located in both mitochondria and cytosol. Similar levels of both Bcl-2 and Bcl-XL were present in the resting mitochondria of the two cell lines. Although the proapoptotic proteins Bcl-XS, Bad, and Bax were mainly located in the cytosol, CEM/VLB100 mitochondria expressed higher levels of these proapoptotic proteins. Subcellular redistribution of the Bcl-2 family proteins was detected in a cell-free system by both Western blotting and flow cytometry after exposure to TNF-alpha. The levels of Bcl-2 family proteins were not altered at the whole cell level by TNF-alpha. However, after exposure to TNF-alpha, Bax, Bad, and Bcl-XS translocated from the cytosol to the mitochondria of both cell lines. An increase in Bcl-2 levels was observed in CEM mitochondria, which showed resistance to TNF-alpha-induced cytochrome c release. By contrast, decreased mitochondrial Bcl-2 was observed in CEM/VLB100 cells, which released cytochrome c from the mitochondria and underwent apoptosis as detected by fluorescence microscopy. We conclude that mitochondrial levels of Bcl-2 family proteins may determine the sensitivity of leukemic cells to apoptosis and that, furthermore, these levels may change rapidly after exposure of cells to toxic stimuli.
Antineoplastic Agents, Phytogenic↗
Multiparameter flow cytometric analysis of polymorphonuclear leucocytes in whole blood from patients with adult rapidly progressive periodontitis reveals low expression of the adhesion molecule L-selectin (Cd62L).
Numerous studies of polymorphonuclear leucocyte (PMN) function in patients with adult periodontitis, including rapidly progressive periodontitis, have yielded conflicting findings, perhaps because most of the assays were performed on PMNs that had been separated from whole blood by a variety of procedures. To avoid the problems associated with in vitro analysis of isolated cells, PMN function and antigen expression in live whole unmanipulated blood of eight patients with rapidly progressive periodontitis were compared with those of age-, race-, and sex-matched controls. Using multiparameter flow cytometry, a) L-selectin (CD62L) expression, b) cell size, and c) respiratory burst activity were measured in PMNs in whole blood immediately ex vivo and during incubation with Porphyromonas gingivalis and Staphylococcus aureus. By comparison with PMNs from the control group, PMNs from the patient group expressed significantly lower levels of CD62L and had an increased size before stimulation. PMNs from both groups produced respiratory bursts similar to those of the two bacteria, but in both groups the responses to S. aureus were significantly greater than those to P. gingivalis. The significantly reduced expression of the adhesion molecule CD62L on PMNs in the patient group may lead to reduced tethering of neutrophils at sites of inflammation and may partly explain the susceptibility of these individuals to recurrent and severe periodontal infections.
Adult↗
Rapid flow cytometric identification of putative CD14- and CD64- dendritic cells in whole blood.
Blood dendritic cells (DCs) may be identified as mononuclear leucocytes with high expression of HLA-DR, but lacking the antigens CD3, CD14, CD16, CD19, and CD56, which are characteristically expressed by T cell, monocytes, B cells, and natural killer cells. However, some DCs have recently been reported to express the monocyte-associated antigen CD14; also some monocytes may shed CD14 and so appear to be CD14-. It is therefore possible that the expression of CD64, which is absent on blood DCs but which is expressed by both CD14+ and CD14- monocytes may better distinguish DCs from monocytes. DCs were identified by flow cytometry as mononuclear leucocytes with the phenotype HLA-DR+, CD2-, CD16-, CD19-, CD57-, and either CD14- or CD64- and hence are described herein as either CD14- DCs or CD64- DCs, respectively. CD14- DCs and CD64- DCs occurred, respectively, at a concentration of 65 +/- 48 x 10(6) cells 1(-1) and 149 +/- 103 x 10(6) cells 1(-1) (mean +/- S.D.) in samples of peripheral blood (corresponding, respectively, to 3.0 +/- 1.8% and 6.6 +/- 3.8% of the mononuclear cells). The expression of CD14 and CD64 on monocytes in blood was also investigated. Cells with the immunophenotype CD14- CD64+ comprised 12.7 +/- 3.3% of the monocyte population and had high expression of HLA-DR. DCs identified as CD14- or CD64- were isolated by flow cytometric sorting, prepared for electron microscopy, and both were found to have the characteristic morphology of resting DCs. We conclude that mononuclear cells with the phenotype HLA-DR+, CD3-, CD16-, CD19-, CD56-, and CD64- are blood DCs that may be CD14+ or CD14-. The method described therefore provides a more accurate and rapid means of identifying circulating DCs.
Adult↗
Comparative expression of major histocompatibility complex (MHC) antigens on CD5+ and CD5- B cells in patients with chronic lymphocytic leukaemia (CLL)
The aim of this study was to investigate the expression of major histocompatibility complex (MHC) antigens on CD5+ and CD5- B cells of 13 patients with chronic lymphocytic leukaemia (CLL). This was carried out using a series of monoclonal antibodies (MAbs) against polymorphic and monomorphic class I and class II antigens, as well as to the transferrin receptor and assessed by flow cytometry and direct and indirect immunofluorescence. The expression of these molecules was assessed as mean fluorescent intensity (MFI). The results showed that cells from all 13 individuals expressed monomorphic class I antigens. The number of cases expressing polymorphic HLA-Bw6, -Bw4, -B7, -B27 and -A2 class I antigens on CD5- B cells was 11 (85%), 6(46%), 2(15%), 1(8%), 3 (23%), respectively, which was consistent with the expected population frequency distributions of these antigens. For each of the class I antigens on CD5+ and CD5- B cells, the ratio of the MFI was greater than 1 in 12 of 13 cases. For the transferrin receptor (CD71), this ratio was also almost always greater than 1. These results indicate that, unlike solid tumours where the loss or abnormal expression of class I and II antigens is a frequent event, the expression of class I antigens in CLL patients seems to be normal. This indicates that the loss of these antigens cannot provide the leukaemic cells with a selective advantage to escape immunological detection.
Antigens, Neoplasm↗
Protein A immunoadsorption in chronic refractory ITP reverses increased platelet activation but fails to achieve sustained clinical benefit.
Adults with chronic relapsing ITP present a difficult therapeutic challenge. The ongoing antibody-mediated platelet destruction in this group might be expected to be associated with increased expression of platelet surface membrane activation antigens. We have studied a group of 10 patients with refractory ITP and 35 healthy controls. Using an immediate, sensitive, unfixed, whole blood, flow cytometric method to detect platelet surface P-selectin and GP53, we have detected markedly increased platelet activation in the ITP group compared with the controls (P-selectin; patient median 24.5% v control median 2.0%. GP53 median 6.5% v 2.1%, P < 0.01 for both). Five patients underwent protein A immunoadsorption therapy. The effect of protein A immunoadsorption on platelet activation before, during and after 18 treatments in these patients was studied and patients were followed-up to assess clinical outcome. Platelet-associated immunoglobulin measurements were made before and at the end of six treatments. Platelet activation decreased after immunoadsorption. P-selectin expression fell significantly; pre- and post-treatment median values differed by 15.5%, P < 0.01, for GP53 the difference was 2.5%, P = NS. A reduction in both platelet-associated IgG (median reduction of 11.8 ng/10(6) platelets, P = 0.08) and IgM (7.6 ng/10(6) platelets, P = 0.06) was recorded.
Adult↗
A CD4+ proliferation of large granular lymphocytes expresses the protease activated receptor-1.
The platelet-type thrombin receptor was the first member to be identified in a family of protease activated receptors (PARs) and has been designated PAR-1. We recently reported that the large granular lymphocytes (LGLs) in patients with proliferations of CD8+ cells co-expressed PAR-1 and the expression of PAR-1 correlated with the expression of CD57. Here we show, by three-colour immunofluorescence, that the LGLs from a patient with a rare CD4+ CD57+ monoclonal expansion also expressed PAR-1. Northern blot analysis confirmed the presence of high levels of mRNA for PAR-1 in these LGLs.
Aged↗
The protease-activated receptors and their cellular expression and function in blood-related cells.
Explore the source record for details and available documents.
Blood Cells↗
Immunolocalization of protease-activated receptor-2 in skin: receptor activation stimulates interleukin-8 secretion by keratinocytes in vitro.
The protease-activated receptor-2 (PAR-2) is a seven transmembrane domain receptor related to the thrombin receptor, which is activated in vitro by cleavage by trypsin. Affinity-purified rabbit IgG raised against a peptide corresponding to the trypsin cleavage site of PAR-2 was used for an immunohistochemical study of skin. The expression of PAR-2 in epidermis was striking, with keratinocytes showing abundant intercellular and cytoplasmic staining. Basal cells showed the strongest staining intensity and the stratum corneum was negative. Staining with control IgG used at the same concentration was consistently negative. The functional expression of PAR-2 by the simian virus transformed human skin keratinocyte cell line SVK14 was demonstrated by Northern blot analysis, flow cytometric analysis and the measurement of intracellular calcium. Treatment of SVK14 with trypsin or a receptor agonist peptide (SLIGKV-NH2) caused a dose-dependent increase in the secretion of the chemokine interleukin-8 (IL-8) in vitro. The effect of the peptide was specific, since control acetylated peptide was without activity. We conclude that PAR-2 is highly expressed by epidermal keratinocytes and receptor activation in vitro leads to increased IL-8 secretion by keratinocytes. These data raise the possibility that PAR-2 may play a role in epidermal homeostasis and inflammatory conditions.
Blotting, Northern↗
Intra-epithelial subpopulations of T lymphocytes and Langerhans cells in oral lichen planus.
This study has addressed the question of whether there is selective recruitment and distribution of intra-epithelial leucocytes in lesions of oral lichen planus (OLP). T-lymphocyte subsets were examined in the epithelium and peripheral blood of patients and controls using flow cytometry and double immunofluorescence, and the relationship between keratinocyte intercellular adhesion molecule-1 (ICAM-1) expression with T-lymphocyte and Langerhans cell (LC) distribution was examined. The circulating 'memory' subset (CD45RO+) of T-helper cells (CD4+) was increased from 49.1% in controls to 65.7% in patients (P=0.005), while the 'naive' subset (CD45RA+), which was absent from control epithelium, comprised 24% of helper cells in OLP (P=0.016). Fewer LC expressed CD45RO in OLP than in controls (P=0.037) and all T-cell and LC counts were significantly raised in ICAM-1-expressing areas of epithelium. These data demonstrate changes in intra-epithelial T-lymphocyte and LC populations compared with normal oral mucosa and suggest there is selective recruitment in OLP. In addition, keratinocyte ICAM-1 expression does appear to be associated with accumulation of infiltrating T lymphocytes and LC.
CD4-Positive T-Lymphocytes↗
Protease-activated receptors and their role in IL-6 and NF-IL-6 expression in human gingival fibroblasts.
The serine protease thrombin is formed at sites of coagulation and inflammation and has been shown to have important proinflammatory cellular effects relevant to the pathogenesis of periodontal disease. Thrombin acts via specific cell surface receptors termed protease-activated receptor-1 (PAR-1) and PAR-3, which have a distinctive method of activation. Proteolytic cleavage of the extracellular domain by thrombin reveals a hidden amino terminus which then acts as a "tethered ligand". A short synthetic peptide (SFLLRN) can also mimic the tethered ligand and activate PAR-1 but not PAR-3. Also, a trypsin-sensitive receptor termed PAR-2 has been described which is activated by the PAR-1 activating peptide SFLLRN. Here we show conclusively by flow cytometric and Northern blot analysis that human gingival fibroblasts (HGF) express PAR-1 but not PAR-2. In functional studies we also show that thrombin and SFLLRN stimulated increased expression of mRNA encoding nuclear transcription factor NF-IL-6 and IL-6 in vitro. At optimal concentrations, thrombin (10(-7) M) induced 7.6 +/- 0.01 ng/ml immunoactive IL-6 and PAR-1 activating peptide (5 x 10(-5) M) induced 2.2 +/- 0.2 ng/ml (mean +/- standard error of mean). A proteolytically inactive recombinant thrombin (serine 195 to alanine) was without activity. These data show that HGF express PAR-1 and suggest that PAR-1 activation stimulates increased NF-IL-6 and IL-6 gene expression and IL-6 secretion by HGF in vitro. Whether HGF express PAR-3 is unknown, but the fact that SFLLRN was not a complete replacement for thrombin raises the possibility that HGF may express additional thrombin receptors. These findings add weight to the importance of the cytokine-like role played by thrombin and raise the possibility that protease-activated receptors may play a role in the pathogenesis of inflammatory periodontal disease.
Blood Coagulation↗
How should CD34+ cells be analysed? A study of three classes of antibody and five leucocyte preparation procedures.
For patients undergoing stem cell transplantation after intensive marrow ablative therapy it is important to enumerate the CD34+ stem cells in peripheral blood so that the harvest can be timed in order to maximize the number of cells collected by leucophoresis for subsequent haematopoietic reconstitution. The use of rapid flow cytometric techniques for the determination CD34+ leucocyte numbers has been advocated, although there is no consensus as to the best method. In this study, we have examined the effects of preparation procedures for flow cytometry on the binding of four CD34 antibodies (Immu-133, QBEND-10, HPCA2 and BIRMA-K3) to the three classes of epitopes on leucocytes. Whole blood, bone marrow and leucophoresis samples were analysed either directly after labelling with a vital nuclear dye (LDS-751) and fluorochrome-conjugated antibodies or after additional erythrocyte lysis and leucocyte fixation using four commercially available reagents (Q-Prep, OptiLyse B, OptiLyse C and FACS Lysing Solution). By comparison with the results obtained from viable leucocytes in unmanipulated samples, it was found that the binding of all four antibodies could be affected by lysis and fixation procedures and that the binding of the class I antibody Immu-133 was most markedly decreased. We conclude that CD34+ cells are best analysed using a whole blood procedure in which nucleated cells are identified by their side light scatter and the fluorescence associated with a vital nuclear dye (in this instance LDS-751) and the CD34+ cells are detected with fluorescein isothiocyanate- or phycoerythrin-conjugated antibodies.
Animals↗
The Q-Prep system: effects on the apparent expression of leucocyte cell surface antigens.
To facilitate the analysis of immunolabelled peripheral blood or bone marrow leucocytes by flow cytometry, a number of reagents are available commercially that lyse erythrocytes and fix leucocytes. This study has investigated the effect on antibody-labelled whole blood of the Q-Prep procedure, in which erythrocytes are lysed with formic acid, and leucocytes are fixed with formaldehyde. Whole blood samples were labelled with the nuclear dye LDS-751 and with antibodies to HLA-DR or belonging to CD2, CD3, CD4, CD7, CD8, CD10, CD13, CD14, CD19, CD20, CD29, CD33, CD45, CD45RA, CD56, and CD62L (TQ-1) that were directly conjugated to either phycoerythrin (PE) and/or fluorescein isothiocyanate (FITC). Leucocytes were analysed by flow cytometry either in unfixed, unlysed whole blood (15) or after preparation using the Q-Prep system. The binding of eight antibodies, CD19-FITC, CD2-PE, CD3-PE, CD4-PE, CD19-PE, CD29-PE, CD45RA-PE, and CD56-PE, to the surface of lymphocytes was reduced, resulting in significant changes (P < 0.05) in the percentages of cells that stained positively and/or their mean molecules of equivalent fluorochrome (MEF). Further analysis revealed that this was due to the formic acid used during the erythrocyte lysis stage.
Antibodies, Monoclonal↗