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2 Integrins1
*
Center for Inflammation Research, Department of Clinical and Surgical Sciences (Internal Medicine), Royal Infirmary, Edinburgh, Scotland;
Infectious Diseases Division, Washington University School of Medicine, St Louis, MO 63110; and
Department of Pathology, Harvard Medical School, Brigham and Women’s Hospital, Boston, MA 02115
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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. Such ingestion was
specifically inhibited by Abs to thrombospondin-1 and the
v
3 vitronectin receptor. Murine bone
marrow-derived macrophage phagocytosis of late and early apoptotic
neutrophils occurred by similar mechanisms, proceeding with the same
efficiency as that observed for wild-type controls when macrophages
from m-/- or
2-/- mice were used. We conclude that
specific nonphlogistic, 2 integrin-independent
mechanisms involving thrombospondin-1 and
v3 allow macrophages to ingest late
apoptotic neutrophils without eliciting inflammatory cytokine
secretion. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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However, the molecular mechanisms mediating safe phagocytic clearance of apoptotic cells remain poorly understood; an increasing number of phagocyte receptors (see Refs. 14, 15, 16 for reviews) have been implicated in vitro. This complexity may reflect the fact that studies have frequently involved administration to phagocytes of "meals" consisting of heterogeneous populations containing cells at various stages of the death program, including secondary necrosis (17). By contrast, human neutrophils undergoing constitutive apoptosis during overnight culture contain a mixture of histologically normal neutrophils (not ingested by phagocytes) and intact cells that exclude trypan blue and propidium iodide (PI)3 and exhibit classical morphologic features of early apoptosis (3). These include nuclear coalescence and chromatin condensation accompanied by well-defined surface changes such as the capacity to bind annexin V (18, 19, 20). By separating intact apoptotic neutrophils from histologically normal neutrophils within the same population of aging cells, we confirmed that phagocytes recognized only the apoptotic neutrophils (3). Nevertheless, even this apparently "clean" model system has proved more complex than was first thought. Beyond 18 h in culture, a steadily increasing proportion of senescent neutrophils exhibit a characteristic late apoptotic morphology in which nuclear degradation or so-called evanescence is accompanied by electron microscopic evidence of limited granule fusion with the plasma membrane (21, 22). To avoid confusion, we propose that neutrophils with classical features of apoptosis (3) should be regarded as early apoptotic cells.
We have become interested in whether late apoptotic neutrophils are
recognized by macrophages (M
s) and, if so, the molecular mechanisms
and consequences of this event. A number of different types of
phagocytes can deploy the phagocyte surface
v3 vitronectin
receptor integrin to present bridging thrombospondin 1 (TSP1) to
apoptotic cells and promote phagocytosis without inciting
proinflammatory secretory responses (10, 11, 23, 24). This
mechanism was a strong candidate for M recognition of late apoptotic
neutrophils, because 1) these cells exhibit limited fusion with the
plasma membrane of granules containing proteins capable of binding TSP1
(21, 22, 25); 2) a very recent report indicates that late
apoptotic neutrophils bind TSP1 with such efficiency that this can be
demonstrated with soluble biotinylated TSP1 (19); and 3)
myeloid dendritic cells bind late apoptotic cells via an
v-mediated mechanism (26).
However, equally strong candidate phagocyte receptors were those of the
2 integrin family that bind opsonic complement
fragments, type 3 complement receptor (CR3;
m2 or CD11b/CD18) and
CR4 (x2 or
CD11c/CD18). Not only does ligation of these receptors fail to
stimulate the release of inflammatory mediators from Ms (27, 28), but there is also evidence that they can bind, via opsonic
complement fragments, populations of dying cells (17, 29).
Furthermore, 2 integrins can also bind
denatured proteins (30), which might be exposed by late
apoptotic cells.
Therefore, in this study we set out to determine whether it was
possible to purify late apoptotic neutrophils from cultured neutrophil
populations undergoing constitutive death, whether such cells were
nonphlogistically ingested by Ms, and whether either M
TSP1/v3 or
2 integrins mediated phagocytosis of late
apoptotic neutrophils.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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All chemicals were purchased from Sigma (St. Louis, MO) unless otherwise indicated. Culture media (HBSS, IMEM, and DMEM) and supplements (100 U/ml penicillin, 100 µg/ml streptomycin, 2 mM glutamine, and 10% FCS) were obtained from Life Technologies (Grand Island, NY). Sterile tissue culture plasticware was purchased from Falcon Plastics (Cockeysville, MD).
Abs and peptides
mAb to the human vitronectin receptor integrin (31)
was the V3-specific
mAb 23C6 (IgG1; provided by Prof. M. Horton, St. Bartholomew’s Medical
School, London, U.K.). V. Dixit (University of Michigan, Ann Arbor, MI)
provided mTSP1, a rabbit affinity-purified polyclonal Ab specific for
mouse TSP1 (32), and A6.1, an IgG1 murine mAb for human
TSP1 (33). H9.2B8, a hamster mAb specific for the mouse
integrin v chain (34) was
obtained from PharMingen (San Diego, CA). The control mAb was mAb OX-7
(from Serotec, Banbury, Oxon, U.K.), an IgG1 that recognized Thy 1.1.
The tetrapeptides Arg-Gly-Asp-Ser (RGDS) and Arg-Gly-Glu-Ser (RGES)
were obtained from Sigma.
Human leukocytes
Neutrophils were isolated from fresh citrated normal human blood
by dextran sedimentation and plasma-Percoll discontinuous density
gradient centrifugation and were "aged" in tissue culture in IMEM
with 10% autologous platelet-rich plasma-derived serum (PRPDS) so as
to undergo apoptosis, exactly as previously described (3).
Late apoptotic neutrophils were purified from 22-h aged
polymorphonuclear neutrophil granulocyte (PMN) by discontinuous
plasma-Percoll density gradient centrifugation; as described later in
this report, >95% pure late apoptotic cells were isolated at the
interface between platelet-poor plasma (PPP) and 31% Percoll in PPP,
whereas a mixed population of late apoptotic and early apoptotic cells
was found at the interface of 31 and 42% Percoll in PPP; the latter
was not used in phagocytosis assays. A mixed population of early
apoptotic and nonapoptotic neutrophils free of late apoptotic cells was
retrieved at the 42–51% Percoll in PPP interface; this last
population was used as early apoptotic neutrophils in studies of
recognition by M (see below), as all our previous studies have used
similar mixed populations that routinely arise after overnight aging in
culture, because such cells are >99% viable by trypan blue exclusion
(3, 6, 23, 24). Gradients were centrifuged at 610 x
g for 24 min at 4°C. Human monocytes (>90% pure) were
prepared by counterflow centrifugation as described previously
(35) and cultured for 5 days in IMEM with 10% autologous
prpds to mature into M as previously described
(35).
Isolation and culture of mouse M
Bone marrow was harvested from BALB/c mice and plated in 96-well
plates in DMEM containing 10% FCS and 10% L929 cell-conditioned
medium as a source of M-CSF. Bone marrow M were used in phagocytosis
assays after 7 days of growth in culture as previously described
(34).
In some experiments M were prepared as described above from
gene-targeted mice and wild-type strain controls as follows:
m (CD11b)-/- BALB/c
mice and BALB/c controls were used as previously described
(36); 2 (CD18) null mice were
crossed from 129sv/eg onto the C57BL/6J background, and
F2 CD18-/- animals were
used as founders for the CD18-/- mice used in
the current experiments, with control mice bred from 129sv/eg and
C57BL/6J in parallel (37).
Assessment of PMN morphology and flow cytometric analysis
Early apoptotic and late apoptotic PMN were assessed by microscopic examination of cytocentrifuge preparations fixed in methanol and stained with May-Giemsa or by transmission electron microscopy as previously described (3). Binding of FITC-conjugated annexin V in ice-cold PBS containing calcium and magnesium as previously described (18, 20) was used to assess exposure of phosphatidylserine exposure. PI was used to assess plasma membrane permeability. Cells were exposed to PI at 1 µg/ml for 120 s immediately before flow cytometric analysis; a positive control was provided by brief heating of 22-h aged neutrophil populations to 100°C. Labeled cells were applied to a Becton Dickinson FACScan flow cytometer (Mountain View, CA) that automatically and simultaneously measured the fluorescence of individual cells identified by their size-dependent light-scattering properties.
Interaction assay
A coded, observer-blind, microscopically quantified phagocytic
assay of M ingestion of apoptotic PMNs, which has been extensively
described, illustrated, and validated (3, 23, 24, 38), was
used in these studies. Apoptotic and late apoptotic PMNs prepared as
described above from a single population of 22-h aged PMNs were washed
once in HBSS and suspended in IMEM, and 0.5 x
106 PMN in 50 µl of medium were added to each
washed well of M cultured in 96-well plates. After interaction for
30 min at 37°C in 5% CO2, the wells were
washed in cold (4°C) 0.9% saline to remove noningested PMNs, and
then the M monolayer was fixed in 2% glutaraldehyde in saline for 2
min and stained for myeloperoxidase (MPO), and the proportion of
M-ingesting PMNs was counted by inverted light microscopy, exactly
as previously described (3, 23, 24, 38). Because of a
tendency of nonapoptotic neutrophils to adhere to mouse bone marrow
M after 30-min interaction, mouse M were then trypsinized, and a
separate cytocentrifuge preparation was prepared for each well as
previously described (11, 35). These were fixed with 2%
glutaraldehyde, stained for MPO, and finally counterstained with
Hemalum (BDH, Poole, U.K.). The proportion of mouse M-containing,
brown-staining, MPO-positive PMNs was then counted.
Effects of serum
To determine whether there were effects of serum on the
phagocytosis of early apoptotic and late apoptotic PMN, such PMNs were
interacted with human monocyte-derived M in the presence of 15%
normal nonheated autologous human PRPDS or serum prepared in glass and
15% normal heated (56°C for 30 min) autologous human PRPDS or serum
from glass.
Effects of Abs
These were determined as previously described (23, 24, 34, 38). M in 96-well plates were washed, and 50 µl of Ab at
the desired concentration in IMEM was added to each well. The plates
were incubated for 15 min at 4°C, followed by addition of 0.5 x
106 PMN in 10 µl of IMEM at 37°C, and then
interacted for 30 min under standard conditions.
Effects of soluble inhibitors
Various inhibitors were included in the interaction medium. The tetrapeptide RGDS and the control peptide RGES were made up in IMEM before being added to the interaction medium to achieve the desired concentration (1 mM).
Assessment of M response to ingestion of late apoptotic cells
Human M were washed with HBSS, then incubated with apoptotic
PMN, late apoptotic PMN, and control particles in IMEM for 30 min. The
noningested apoptotic PMN and control particles were washed away,
and IMEM was added for 16 h. Supernatants were collected
at this time point because cytokine secretion stimulated by opsonized
zymosan was maximal (13). Supernatants were centrifuged at
6000 rpm for 3 min to remove particulate debris. Cytokine
concentrations in the culture supernatants were assayed by ELISA for
TNF- and IL-8 using specific assays as previously described
(11).
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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In keeping with the studies by Hébert et al.
(21), we observed increasing proportions of apparently
anucleate late apoptotic neutrophils after 18 h of culture of
normal human peripheral blood neutrophils (Figs. 1
and 2).
We reasoned that it might be possible to purify late apoptotic
neutrophils by density centrifugation on discontinuous Percoll-plasma
gradients. From neutrophil populations aged in vitro for 22 h, we
were able to obtain a fraction from the 0/31% Percoll interface
containing >95% pure late apoptotic cells (Fig. 3A) with typical nuclear
evanescence (21) and other characteristic features
confirmed by electron microscopy (Fig. 3B) and a distinct
fraction of aged neutrophils from the 42/51% Percoll interface
displaying a mix of morphologically normal and early apoptotic
neutrophils (Fig. 3C) closely similar to the overnight-aged
neutrophil populations used in our previous studies of phagocyte
recognition of early apoptotic neutrophils (23, 24, 34, 38). Typically around 50% of cells in this fraction displayed
early apoptotic morphology (Fig. 3C; see also Fig. 4B).
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A) to a degree similar to that
exhibited by the 50% of early apoptotic cells in the fraction from the
42/51% Percoll interface (Fig. 4B, lower right
quadrant). The late apoptotic neutrophil population exhibited
slightly greater permeability to PI than early apoptotic cells (compare
Fig. 4, A and B), although much less than that
exhibited by heat-permeabilized 22-h aged neutrophils (Fig. 4C). These data indicated that late apoptotic neutrophils
exhibited some increase in plasma membrane permeability despite being
morphologically intact. However, the late apoptotic neutrophil fraction
isolated from 22-h aged neutrophil populations did not begin to undergo
secondary necrosis, as evidenced by detectable spontaneous release of
the granule constituent MPO, until recultured under standard conditions
for at least 4 h (data not shown).
Human monocyte-derived M phagocytosis of late apoptotic cells is
nonphlogistic
Previously we (10, 11, 39) and others
(13) reported that uptake of apoptotic cells did not
trigger release of proinflammatory cytokines from Ms and other
phagocytes. However, M did release such cytokines when
ingesting debris from granulocytes that had undergone secondary
necrosis after constitutive apoptosis (39). Consequently,
it was important to determine the response made by M taking up late
apoptotic neutrophils. Following a 30-min interaction with late
apoptotic neutrophils as described in Materials and Methods,
40.2 ± 1.8% (mean ± SE; n = 6) of human monocyte-derived
M ingested late apoptotic neutrophils. However, by contrast with
uptake of opsonized zymosan, there was no release of the
proinflammatory cytokines, IL-8 or TNF-, indicating that uptake of
late apoptotic neutrophils was also nonphlogistic (Table I).
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phagocytosis of late apoptotic cells is not modulated by
serum, but is inhibited by Abs to TSP1 and
v3
Although our previous studies have routinely used human
neutrophils and M cultured in autologous serum obtained by
recalcifying platelet-rich plasma (PRPDS), we have routinely washed
both cell types before interaction in the absence of added serum
(3, 23, 24, 35, 38). A recent report, using an assay of
aged neutrophil interaction with human M in which much of the
interaction signal appeared to be tethering of apoptotic cells rather
than phagocytosis, suggested that interaction could be markedly
enhanced by the presence of up to 15% serum as a source of complement
(29). Nevertheless, the inclusion of 15% autologous serum
prepared in glass did not enhance human monocyte-derived phagocytosis
of either late apoptotic or early apoptotic neutrophil fractions in our
assay (Fig. 5). Furthermore, the use of
15% PRPDS also failed to enhance phagocytosis of each cell type (data
not shown). By contrast, mAbs (but control mAb) to TSP1 and
v3 significantly
inhibited human monocyte-derived M phagocytosis of both late and
early apoptotic neutrophil fractions (Fig. 6), but not uptake of opsonized RBC used
as controls (data not shown for clarity).
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phagocytosis of late apoptotic
neutrophils is also inhibited by Abs to TSP1 and v
Our previous work suggested that murine bone marrow-derived M
use mechanisms similar to those of human monocyte-derived M in
uptake of human early apoptotic neutrophils; inhibition by RGDS peptide
and anti-murine v mAb is demonstrable
(34). Not only did these reagents inhibit uptake of late
apoptotic neutrophils by murine bone marrow-derived M (but not
control RGES peptide or control mAb; Fig. 7), but inhibition was observed with an
affinity-purified rabbit Ab to TSP1 (but not by control rabbit IgG). No
reagent used inhibited uptake of opsonized erythrocytes (data not shown
for clarity).
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2 integrins are not necessary for efficient M
uptake of early and late apoptotic neutrophils
Because ligation of M CR3 and CR3-mediated uptake of particles
have been reported not to activate
proinflammatory responses from M (27, 28), we
considered it important to examine the role of
2 integrins in M uptake of early and late
apoptotic neutrophils, particularly the
m2/CD11b CD18 CR3
integrin. Consequently, we sought definitive evidence of a requirement
for m2 or other
2 integrins by studying M from
gene-targeted mice. In experiments using bone marrow-derived M from
m-/- mice and
wild-type controls, no difference was observed in the proportion of
M ingesting late apoptotic neutrophils; these were highly
efficiently ingested by 71.8 ± 5.3% of
m-/- M and
66.7 ± 5.9% of wild-type M (mean ± SE;
n = 3; i.e., three mice in eachgroup; experiments were
also performed in triplicate in M from each mouse). These findings
were confirmed in a more extensive series of experiments using bone
marrow-derived M from
2-/- and wild-type
control mice; there was no difference in the proportion of M
ingesting either apoptotic or late apoptotic neutrophils (Fig. 8). Indeed, although recognition of late
apoptotic neutrophils was generally slightly greater in absolute degree
than uptake of early apoptotic cells in each set of experiments,
perhaps reflecting unavoidable dilution of early apoptotic cells by
copurified nonapoptotic neutrophils, the mechanism of recognition by
bone marrow-derived M from wild-type or
2-/- mice appeared
very similar despite variation in the baseline degree of phagocytosis
between sets of experiments consistent with previous experience
(11, 34). Thus, specific inhibition of bone marrow-derived
M uptake of late apoptotic neutrophils was observed with RGDS
peptide at 1 mM, but not control RGES peptide, and was seen also with
Ab to murine vitronectin receptor (v), but not
control Ab (Fig. 8).
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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s. In this report we
have demonstrated that fractions of morphologically defined late
apoptotic neutrophils can be purified from populations of senescent
human neutrophils. Furthermore, in keeping with previous data obtained
with populations of ‘early’ apoptotic neutrophils (10, 11), late apoptotic neutrophils were efficiently ingested by
human monocyte-derived M without triggering release of the
pro-inflammatory mediators IL-8 and TNF-. By contrast with a
previous report (29), the proportion of human
monocyte-derived M ingesting early apoptotic neutrophils was not
increased by the presence of serum and no increase in uptake of late
apoptotic neutrophils was observed. These data argued against a role
for M 2 integrins in uptake of dying
neutrophils. However, the uptake of late apoptotic neutrophils by both
human monocyte-derived M and murine bone marrow-derived M was
inhibited by Abs to TSP1 and the vitronectin receptor, as was ingestion
of early apoptotic neutrophils. Furthermore, strong evidence against a
requirement for 2 integrins in efficient M
phagocytosis of either early or late apoptotic neutrophils was provided
by the failure of Ms from
m-/- and
2-/- knockout mice to
exhibit any defect in phagocytosis of either target.
Our first major conclusion from these data is that progression beyond
the (early) apoptotic state originally defined in our studies of the
constitutive death of cultured neutrophils (3) does not
deny senescent neutrophils the opportunity for safe clearance while in
the late apoptotic state before potentially deleterious secondary
necrosis. Although our assessment of the proinflammatory secretory
response from Ms taking up late apoptotic neutrophils was limited to
assay of M release of the key chemokine IL-8 and the master
inflammatory mediator TNF-, previous studies (11, 12, 13)
indicate that other classes of inflammatory mediator are unlikely to be
released by M under these circumstances. The current data
re-emphasize the tissue-protective potential of neutrophil clearance by
apoptosis, demonstrating that even cells reaching what might be termed
the "last chapter" of constitutive death can be cleared safely.
However, our data also indicate that it may prove difficult to
selectively define the potential for tissue protection afforded by
specific clearance of late apoptotic neutrophils in vivo. This is
because M phagocytosis of both early and late apoptotic neutrophils
appears likely to involve similar mechanisms in which TSP1 and the
vitronectin receptor play a major role. Thus, it may prove difficult to
inhibit uptake of early apoptotic cells selectively, because this would
be necessary for a formal assessment of the capacity of M
phagocytosis of late apoptotic neutrophils to serve as a last line of
tissue defense in inflammation. Nevertheless, despite a growing
understanding of molecular mechanisms mediating phagocytic clearance,
we still know very little of those mechanisms that predominate in the
clearance of apoptotic cells from various sites in the living mammal.
Future work should take into account the possibility that clearance
mechanisms dedicated to removal of late apoptotic cells could exist.
Some support for this possibility can be drawn from the observation by
Rubartelli et al. that myeloid dendritic cells may use
v integrins in selective ingestion of late
apoptotic cells (26).
The second major finding of our study also emphasizes that much remains
to be learned about mechanisms mediating M ingestion of cells dying
by apoptosis. The data clearly demonstrate that expression of
2 integrins is not necessary for efficient
phagocytosis of either early or late human apoptotic neutrophils by
murine bone marrow-derived Ms (which, nevertheless, appear to use
TSP1/vitronectin receptor-mediated mechanisms similar to those
exhibited by human monocyte-derived M). The current data are in
keeping with our earlier work (3, 38) in an assay system
in which neutrophils underwent apoptosis in the presence of autologous
PRPDS, a source of complement that, according to a recent report,
apoptotic cells may activate so that they become coated with opsonic
complement fragments (29). Nevertheless, when such cells
were interacted in the absence of added serum with human
monocyte-derived M, no defect in phagocytosis of apoptotic
neutrophils was observed despite functionally validated Ab blockade of
M, CR1, CR3, and CR4 receptors (38), nor was any
obvious defect in phagocytosis exhibited by monocyte-derived M
prepared from a patient with severe congenital
2 deficiency (40). However, our
findings must be set against 1) growing evidence that the first
component of complement, C1q, could bridge apoptotic cells to
phagocytes in a manner similar to that proposed for TSP1 (41, 42), and 2) compelling data suggesting that M receptors for
opsonic complement fragments could be important in amplifying efficient
phagocytosis of dying cells (17, 29). Nevertheless, it is
notable that these latter reports have either used mixed populations of
dying cells, including cells in secondary necrosis (17),
or have used assays of interaction with M that include a large
tethering element (29) rather than our own extensively
validated assay of completed phagocytosis. Further studies will be
needed to resolve the importance of complement components in removal of
neutrophils at various stages of the apoptotic death program.
To conclude, our studies demonstrate that late apoptotic neutrophils
can be ingested by Ms via specific mechanisms uncoupled from
secretory proinflammatory responses. Such mechanisms can operate
efficiently in the absence of M 2
integrins, however, emphasizing the need for further characterization
of the role of complement components in the safe clearance of cells
dying by apoptosis.
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Acknowledgments |
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Footnotes |
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2 Address correspondence and reprint requests to Prof. John Savill, Center for Inflammation Research, Department of Clinical and Surgical Sciences (Internal Medicine), Royal Infirmary, Lauriston Place, Edinburgh, Scotland EH3 9YW.
3 Abbreviations used in this paper: PI, propidium iodide; TSP1, thrombospondin 1; CR3/4, complement receptor type 3/type 4; M, macrophage; MPO, myeloperoxidase; PMN, polymorphonuclear neutrophil granulocyte; PPP, platelet-poor plasma; PRPDS, platelet-rich plasma-derived serum; RGDS, Arg-Gly-Asp-Ser; RGES, Arg-Gly-Glu-Ser.
Received for publication October 11, 2000. Accepted for publication January 30, 2001.
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References |
|---|
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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, PGE2 and PAF. J. Clin. Invest. 101:890.[Medline]
RIII and acquire annexin V binding sites during apoptosis in vitro. Blood 85:532.V3 integrin and requires intracellular and extracellular calcium. Eur. J. Immunol. 27:1893.[Medline]
2 integrins bind denatured proteins to mediate leukocyte cell-substrate adhesion. Exp. Cell. Res. 200:242.[Medline]
2 integrin CD11b/CD18 in neutrophil apoptosis: a homeostatic mechanism in inflammation. Immunity 5:653.[Medline]
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 H. P. Su, K. Nakada-Tsukui, A.-C. Tosello-Trampont, Y. Li, G. Bu, P. M. Henson, and K. S. Ravichandran Interaction of CED-6/GULP, an Adapter Protein Involved in Engulfment of Apoptotic Cells with CED-1 and CD91/Low Density Lipoprotein Receptor-related Protein (LRP) J. Biol. Chem., March 29, 2002; 277(14): 11772 - 11779. [Abstract] [Full Text] [PDF]
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 A P Cairns, A D Crockard, and A L Bell CD36-mediated apoptotic cell clearance in SLE Lupus, September 1, 2001; 10(9): 656 - 657. [PDF]
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), early apoptotic neutrophils
(examples marked by open arrows), and a late apoptotic neutrophil
(closed arrow). Note the lack of chromatin in the latter.
), late apoptotic cells (
), and intact cells admitting
trypan blue dye (
) by human monocyte-derived M
