By
From the * Immunology Research Group, the Department of Medicine, and the § Department of
Physiology and Biophysics, University of Calgary, Calgary, Alberta, Canada T2N 4N1
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Abstract |
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Although there is considerable evidence implicating a role for CD43 (leukosialin) in leukocyte
cell-cell interactions, its precise function remains uncertain. Using CD43-deficient mice (CD43/
) and intravital microscopy to directly visualize leukocyte interactions in vivo, we investigated the role of CD43 in leukocyte-endothelial cell interactions within the cremasteric
microcirculation under flow conditions. Our studies demonstrated significantly enhanced leukocyte rolling and adhesion after chemotactic stimuli in CD43
/
mice compared with wild
type mice. Using an in vitro flow chamber, we established that the enhanced rolling interactions of CD43
/
leukocytes, primarily neutrophils, were also observed using immobilized E-selectin as a substrate, suggesting that passive processes related to steric hindrance or charge
repulsion were likely mechanisms. Despite increased adhesion and rolling interactions by
CD43
/
leukocytes, we uncovered a previously unrecognized impairment of CD43
/
leukocytes to infiltrate tissues. Oyster glycogen-induced neutrophil and monocyte infiltration into
the peritoneum was significantly reduced in CD43
/
mice. In response to platelet activating
factor, CD43
/
leukocytes were impaired in their ability to emigrate out of the vasculature.
These results suggest that leukocyte CD43 has a dual function in leukocyte-endothelial interactions. In addition to its role as a passive nonspecific functional barrier, CD43 also facilitates
emigration of leukocytes into tissues.
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Introduction |
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There is now considerable evidence demonstrating that
the recruitment of leukocytes from the circulation to
sites of tissue injury or inflammation is mediated by a sequential cascade of leukocyte-endothelial cell interactions
(1). Tethering and rolling are the first interactions that occur between circulating leukocytes and endothelial cells.
Rolling leukocytes can be activated to firmly adhere to the
vascular endothelium, and subsequently emigrate between
endothelial cells into the extravascular space. Each of these
events is known to be mediated by distinct classes of adhesion molecules; selectins are responsible for leukocyte tethering and rolling, while 2 integrins and members of the immunoglobulin superfamily mediate adhesion and emigration.
In contrast, very little is known about existing antiadhesive
mechanisms that may regulate or attenuate the inflammatory
response. A functional barrier that prevents leukocyte-
endothelial cell interactions through either steric hindrance
or charge repulsion may be one potential mechanism.
One such barrier may be provided by the cell-surface sialoglycoprotein CD43 (leukosialin), a molecule expressed exclusively on hematopoietically derived cells (2, 3). There are several compelling reasons to consider that CD43 may have an important role in cell-cell interactions. First, its structure is consistent with a barrier inasmuch as the extracellular domain of CD43 is extraordinarily long and extends 45 nm from the plasma membrane (4). Through steric hindrance, CD43 may interfere with the ability of other adhesion molecules, including L-selectin (5), to interact with their ligands. Second, CD43 has abundant sialic acid residues that impart a net negative surface charge thought to retard cell-cell interactions (6). Desialation of neutrophils has been associated with a reduction in cell-surface charge and increased adhesiveness, homotypic aggregation, and cell-spreading (6, 7). Third, CD43 is partially downregulated by proteolytic shedding after cellular activation (6, 8) perhaps exposing adhesion molecules and reducing repulsive forces.
Studies using an antibody directed against CD43 do not
support the view that CD43 is antiadhesivein fact this
antibody appears to reduce the recruitment of leukocytes
into tissues (9, 10). Although it is conceivable that anti-CD43 antibodies could paradoxically enhance barrier function by increasing steric hindrance, it is also possible that
CD43 functions as a homing receptor promoting leukocyte
recruitment into tissues or as an accessory molecule enhancing leukocyte rolling, adhesion, and emigration. Using
the CD43-deficient (CD43
/
) mouse described by Manjunath et al. (11) and intravital microscopy to visualize leukocyte kinetics in vivo (12), we directly visualized and investigated the function of CD43 in leukocyte-endothelial cell interactions within the cremasteric microcirculation
under flow conditions. Our results demonstrate that leukocyte rolling and adhesion induced by chemotactic stimuli
are enhanced in CD43
/
mice compared with wild-type
control animals, but unexpectedly there is an inability of
CD43
/
leukocytes (namely neutrophils and monocytes)
to emigrate out of the vasculature.
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Materials and Methods |
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Animals.
CD43-deficient mice (CD43Mouse Cremaster Preparation.
The mouse cremaster preparation was used to investigate leukocyte-endothelial cell interactions in the microcirculation (12). Mice were anesthetized by intraperitoneal injection of a mixture of xylazine hydrochloride (10 mg/kg; MTC Pharmaceuticals, Cambridge, Ontario, Canada) and ketamine hydrochloride (200 mg/kg; Rogar/STB Inc., London, Ontario, Canada). The jugular vein was cannulated and used to maintain anesthesia. The cremaster muscle was dissected free of tissues and exteriorized onto an optically clear viewing pedestal. The muscle was cut longitudinally with a cautery and held flat against the pedestal by attaching silk sutures to the corners of the tissue. The muscle was then superfused with bicarbonate-buffered saline warmed to 37°C. An intravital microscope (Axioskop, Carl Zeiss Inc. Canada, Don Mills, Ontario, Canada) has been described elsewhere. Single unbranched cremasteric postcapillary venules (25-40 µm in diameter) were selected for examination of leukocyte rolling and adhesion. Leukocytes were considered adherent to the venular endothelium if they remained stationary for a periodExperimental Protocol.
To determine whether CD43 was capable of regulating leukocyte recruitment induced by an acute chemotactic stimulus, the response to the bacterial peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP; Sigma Chemical Co., St. Louis, MO) was examined. fMLP (10 µM) was superfused over the cremasteric preparations for 60 min and leukocyte rolling and adhesion in postcapillary venules determined at 15-min intervals.Leukocyte Emigration.
To examine whether leukocyte emigration was impaired in CD43Peritoneal Elicitation.
Mice were given a 1-ml i.p. injection of 1% oyster type II glycogen in sterile saline as previously described (15). After 4 or 24 h, cells were harvested from the peritoneal cavity by lavage via 3 ml of sterile saline, and then counted using a hemocytometer. Differential counting was performed with Wright-Giemsa staining. Finally, to ensure that incomplete harvest was not responsible for lower leukocyte yields in the peritoneum of CD43Flow Chamber Assay.
To study murine leukocyte behavior under shear conditions in vitro, whole blood was perfused over immobilized E-selectin (5 µg/ml), using a previously described flow chamber assay (12). Coverslips were mounted into a polycarbonate chamber with parallel plate geometry (16) and observed at a magnification of 100 using an inverted microscope equipped with phase-contrast optics (Carl Zeiss Inc. Canada). The stage area was enclosed in a warm air cabinet and maintained at 37°C. In brief, the blood was diluted 1:10 in HBSS, maintained at 37°C using a water bath, and perfused through the flow chamber at defined wall shear stresses using a syringe pump (Harvard Apparatus Inc., South Natick, MA). All of the experiments described were performed between 2 and 4 dynes/cm2. The blood was perfused over the substrate for 3 min and then chased with HBSS to flush out any remaining erythrocytes and noninteracting leukocytes. At this stage leukocytes interacting with the coverslip could be seen readily and were counted in at least four random fields per coverslip and expressed as the number of interacting cells per field of view.Statistical Analysis.
All data are presented as mean ± SEM. The data within groups were compared using a paired Student's t test using Bonferroni corrections for multiple comparisons as required. Unpaired t tests were used to compare between groups. Statistical significance was set at P < 0.05. ![]() |
Results and Discussion |
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In vivo fMLP (10 µM) superfusion over the cremasteric microcirculation revealed a significant difference
in leukocyte kinetics between wild-type (CD43+/+) and
CD43/
mice (Fig. 1). Over the first 60 min of fMLP superfusion, the number of rolling cells in CD43
/
animals
was maintained at a constant level and was significantly greater in comparison with wild-type mice (P < 0.05).
Moreover, this higher level of rolling was associated with a
significant augmentation in leukocyte adhesion (31.3 ± 2.8 in CD43
/
vs. 13.3 ± 2.0 in CD43+/+; n = 7 in each
group; P < 0.05). CD43 deficiency did not influence leukocyte rolling velocity.
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These results demonstrate that CD43/
leukocytes have
an enhanced ability to interact with the endothelium of
postcapillary venules in vivo after fMLP stimulation. Direct
visualization of leukocyte-endothelial cell interactions revealed a nonselective effect in that both rolling and adhesion were enhanced in CD43
/
mice after exposure to
fMLP. fMLP directly activates neutrophils to adhere via
CD18-ICAM-1 interactions (17, 18), and our data demonstrate that in the absence of CD43 this interaction was far more avid. Although this is the first documentation of enhanced adhesion in peripheral microvessels in vivo, it is
consistent with an earlier in vitro report demonstrating that
CD43 deficiency can enhance lymphocyte binding to
ICAM-1 and fibronectin (11), and that HeLa cells demonstrate reduced LFA-1-ICAM-1 interactions after CD43
transfection (19). Although an initial report suggested that
CD43 may be proadhesive in that it functions as a ligand for ICAM-1 (20), this observation has not been confirmed
by our study in vivo or by others in vitro (9, 10). The most compelling evidence that CD43 does not function as a
ligand for ICAM-1 is that leukocytes from CD18-deficient
(leukocyte adhesion deficiency type 1) patients with ample
CD43 did not bind to ICAM-1 (21, 22). However, this
does not exclude the possibility that CD43 could be an accessory molecule and not a direct ligand for ICAM-1.
Leukocyte rolling is dependent upon activation-regulated selectins (E and P) on the endothelium (1). To exclude the possibility that enhanced leukocyte rolling observed in vivo in CD43/
animals was due to enhanced
upregulation of endothelial selectins compared with wild-type animals, we compared the ability of CD43+/+ and
CD43
/
leukocytes to interact with immobilized (unalterable) E-selectin in vitro under flow conditions. Fig. 2
demonstrates enhanced interactions of CD43
/
leukocytes in vitro when whole blood was perfused over immobilized E-selectin. Light microscopy of the coverslips for
both wild-type and CD43
/
leukocytes revealed that
>85% of the interacting cells were neutrophils (data not
shown). Differences in circulating leukocyte counts between CD43
/
and CD43+/+ mice do not explain this
result. Peripheral blood total leukocyte counts and differentials were similar in both animal groups, which is consistent with an earlier report (11). These results suggest that
the difference in rolling between CD43
/
and CD43+/+
neutrophils was a passive process perhaps related to charge
or steric hindrance rather than a specific activation or deactivation event associated with CD43
/
mice. Indeed, recent
work suggested ~50% increased tethering of CD43
/
lymphocytes to L-selectin ligands in vivo and in vitro entirely consistent with the view that CD43 indiscriminately
inhibits leukocyte interactions via all three selectins: P-selectin and E-selectin in this study and L-selectin in the work
of Stockton et al. (5). Together the evidence suggests that
CD43 deficiency may have a similar effect on most, if not
all, leukocytes.
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The molecules that support leukocyte rolling (L-selectin, P-selectin glycoprotein ligand-1, and 4-integrin) have
been typically localized to sites on microvilli (23), and
may still be able to interact with ligands despite the presence of CD43. Indeed, our own data clearly demonstrated
that CD43+/+ leukocytes rolled effectively on all of the
substrata studied albeit not as effectively as CD43
/
cells.
An explanation for this difference may be that the negatively charged sialic acid residues on CD43 also contribute
to the functional barrier in an electrochemically repulsive
manner rather than just by steric hindrance. This is consistent with the observation that desialation of neutrophils has
been associated with a reduction in cell-surface charge and
an increase in adhesiveness (6, 7).
Studies using mAbs have not confirmed an antiadhesive
role for CD43. In several studies, cross-linking of CD43 by
antibodies induces leukocyte aggregation (19, 22, 26)
possibly through the regulation of integrin function (22,
29, 30), whereas in other studies anti-CD43 antibodies
have been shown to prevent leukocyte adhesion (9, 10)
and downregulate leukocyte integrin expression (31). Recently, an anti-CD43 antibody (L11) was shown to reduce
neutrophil and monocyte recruitment into the peritoneal cavity (10) as well as block T cell homing into secondary
lymphoid tissues (9). However, based on our results with
enhanced cell adhesion to endothelium, we reasoned that
CD43/
animals would recruit neutrophils into the peritoneum at least as well as CD43+/+ mice. Surprisingly, i.p.
injection of 1% oyster glycogen did not produce the anticipated results (Fig. 3 A). CD43
/
animals had a significant
impairment (
50%) in leukocyte recruitment into the
peritoneal cavity at 4 h (P < 0.05). Cell counting revealed that >97% of the cells isolated were neutrophils in both
groups of animals (data not shown). When these same experiments were performed for 24 h very similar results
were observed (Fig. 3 B). More than a twofold increase in
leukocytes was noted in wild-type animals but at this time
98% of the cells were mononuclear leukocytes.
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These results are consistent with those of McEvoy et al.,
in which anti-CD43 antibodies blocked neutrophil recruitment into the peritoneum (10). However, the lack of recruitment could be due to several mechanisms including
enhanced neutrophil-neutrophil interactions within the
vasculature, increased apoptosis, and macrophage-mediated
clearance of neutrophils within the peritoneum, or impaired emigration. To resolve this issue we elicited leukocyte recruitment out of the cremasteric microvasculature so
that we could directly visualize leukocyte emigration into
tissues. Because fMLP did not elicit a significant increase in
leukocyte emigration, we superfused the cremaster with
PAF. In response to 60 min of optimal concentrations of
PAF (100 nM) (14), the CD43/
animals had a striking,
>50% reduction in leukocyte emigration (13.3 ± 2.0 per
field of view) compared with CD43+/+ animals (31.3 ± 2.8 per field of view). These results demonstrate for the first
time a defect in neutrophil emigration associated with
CD43 deficiency. When the proportion of adherent leukocytes that emigrated was determined for each group (Fig.
4), CD43
/
leukocytes clearly had a significant impairment in emigration. In response to 60 min of PAF, only
20 ± 6% of the adherent CD43
/
leukocytes emigrated
whereas 59 ± 17% of the adherent CD43+/+ leukocytes
emigrated (n = 5 each group; P < 0.01). Preliminary work
from our laboratory suggest that leukocyte movement
across semipermeable membranes was reduced three-fold
in the absence of CD43
/
(Woodman, R.C., and P. Kubes, unpublished observation). These results strongly
suggest that CD43 may have an additional function besides
acting simply as a passive barrier. This may explain the paradox between increased adhesion of CD43
/
leukocytes
in vitro on one hand but an inability in vivo of leukocytes from CD43-deficient animals to effectively emigrate into
tissues as well as clear viral infections (11). It is possible that enhanced adhesive interactions associated with CD43 deficiency may prevent the sequential attachment and detachment required for the leukocyte emigration.
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Based on this series of experiments, our results strongly support the view that CD43 functions to inhibit leukocyte-endothelial cell interactions by limiting rolling and adhesion within the microvasculature. However, once a leukocyte is adherent, CD43 clearly functions to enhance emigration out of the vasculature; complete absence of this molecule leads to a dramatic impairment in leukocyte infiltration into tissues. It is well known that CD43 is proteolytically shed from the surface of phagocytic cells upon activation (6, 8) and that downregulation of CD43 occurs with leukocyte emigration into tissues (32, 33) but, interestingly, there is never complete shedding. In fact, ~50% of the CD43 remains membrane bound even after prolonged exposure to chemotactic factors such as PAF (34). It is conceivable that the remaining CD43 on an adherent leukocyte functions to either signal leukocyte emigration out of the vasculature thus contributing to the emigration process, or reduce leukocyte-endothelial interactions during transmigration. Alternatively, CD43 may repel newly adherent leukocytes which might otherwise bind to the emigrating cell and impair its progress across the endothelium.
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Footnotes |
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Address correspondence to Paul Kubes, Health Science Center, University of Calgary, 3330 Hospital Dr. NW, Calgary, Alberta, Canada T2N 4N1. Phone: 403-220-8558; Fax: 403-283-1267; E-mail: pkubes{at}acs.ucalgary.ca; and reprint requests to Richard C. Woodman, Health Science Center, University of Calgary, 3330 Hospital Dr. NW, Calgary, Alberta, Canada T2N 4N1. Phone: 403-220-7658; Fax: 403-283-1267; E-mail: woodman{at}acs.ucalgary.ca
Received for publication 2 April 1998 and in revised form 5 October 1998.
Research was supported by the Medical Research Council (MRC-MT13563 and MRC-MA14665) of Canada. Drs. Woodman and Kubes are Alberta Heritage Foundation for Medical Research Scholars and Dr. Kubes is a MRC Scientist.The authors thank Lesley Marshall for her expertise in maintaining the CD43 knockout animal colony.
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References |
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1. | Butcher, E.C., and L.J. Picker. 1996. Lymphocyte homing and homeostasis. Science. 272: 60-66 [Abstract]. |
2. | Remold-O'Donnell, E., D. Kenney, and F.S. Rosen. 1987. Expression on blood cells of sialophorin, the surface glycoprotein that is defective in Wiskott-Aldrich Syndrome. Blood. 70: 104-109 [Abstract]. |
3. | Remold-O'Donnell, E., D. Kenney, and F.S. Rosen. 1987. Biosynthesis of human sialophorins and analysis of the polypeptide core. Biochemistry. 26: 3908-3913 [Medline]. |
4. | Cyster, J.G., D.M. Shotton, and A.F. Williams. 1991. The dimensions of the T lymphocytes glycoprotein leukosialin and identification of linear protein epitopes that can be modified by glycosylation. EMBO (Eur. Mol. Biol. Organ.). J. 10: 893-902 [Abstract]. |
5. | Stockton, B.M., G. Cheng, N. Manjunath, B. Ardman, and U. von Andrian. 1998. Negative regulation of T cell homing by CD43. Immunity. 8: 373-381 [Medline]. |
6. | Nathan, C., Q.W. Xie, L. Halbwachs-Mercarelli, and W.W. Jin. 1993. Albumin inhibits neutrophil spreading and hydrogen peroxide release by blocking the shedding of CD43 (sialophorin, leukosialin). J. Cell Biol. 122: 243-256 [Abstract]. |
7. | Gallin, J.I., J.R. Durocher, and A.P. Kaplan. 1975. Interaction of leukocyte chemotactic factors with the cell surface. I. Chemotactic factor-induced changes in human granulocyte surface charge. J. Clin. Invest. 55: 967-974 [Medline]. |
8. |
Remold-O'Donnell, E., and
D. Parent.
1994.
Two proteolytic pathways for downregulation of the barrier molecule
CD43 of human neutrophils.
J. Immunol.
152:
3595-3605
|
9. |
McEvoy, L.M.,
H. Sun,
J.G. Frelinger, and
E.C. Butcher.
1997.
Anti-CD43 inhibition of T cell homing.
J. Exp. Med.
185:
1493-1498
|
10. |
McEvoy, L.M.,
M.A. Jutila,
P.S. Tsao,
J.P. Cooke, and
E.C. Butcher.
1997.
Anti-CD43 inhibits monocyte-endothelial
adhesion in inflammation and atherogenesis.
Blood.
90:
3587-3594
|
11. | Manjunath, N., M. Correa, M. Ardman, and B. Ardman. 1995. Negative regulation of T-cell adhesion and activation by CD43. Nature. 377: 535-538 [Medline]. |
12. |
Hickey, M.J.,
K.A. Sharkey,
E.G. Sihota,
P.H. Reinhardt,
J.D. Macmicking,
C. Nathan, and
P. Kubes.
1997.
Inducible
nitric oxide synthase-deficient mice have enhanced leukocyte-endothelium interactions in endotoxemia.
FASEB (Fed.
Am. Soc. Exp. Biol.) J.
11:
955-964
|
13. | House, S.D., and H.H. Lipowsky. 1987. Leukocyte-endothelium adhesion: microhemodynamics in mesentery of the cat. Microvasc. Res. 34: 363-379 [Medline]. |
14. | Woodman, R.C., P.H. Reinhardt, S. Kanwar, F.L. Johnston, and P. Kubes. 1993. Effects of human neutrophil elastase (HNE) on neutrophil function in vitro and in inflamed microvessels. Blood. 82: 2188-2195 [Abstract]. |
15. | Bhopale, K.K., K.B. Masani, K.S. Pradhan, and C.L. Kaul. 1996. A simple quantitative in vitro macrophage migration assay. Indian J. Exp. Biol. 34: 968-977 [Medline]. |
16. | Lawrence, M.B., C.W. Smith, S.G. Eskin, and L.V. McIntire. 1990. Effect of venous shear stress on CD18-mediated neutrophil adhesion to cultured endothelium. Blood. 75: 227-237 [Abstract]. |
17. | Springer, T.A., W.S. Thompson, L.J. Miller, F.C. Schmalstieg, and D.C. Anderson. 1984. Inherited deficiency of the Mac-1, LFA-1, p150,95 glycoprotein family and its molecular basis. J. Exp. Med. 160: 1901-1918 [Abstract]. |
18. |
Wong, J.,
B. Johnston,
S.S. Lee,
D.C. Bullard,
C.W. Smith,
A.L. Beaudet, and
P. Kubes.
1997.
A minimal role for selectins in the recruitment of leukocytes into the inflamed liver
microvasculature.
J. Clin. Invest.
99:
2782-2790
|
19. | Ardman, B., M.S. Sikorski, and D.E. Staunton. 1992. CD43 interferes with T lymphocyte adhesion. Proc. Natl. Acad. Sci. USA. 89: 5001-5005 [Abstract]. |
20. | Rosenstein, Y., J.K. Park, W.C. Hahn, F.S. Rosen, B.E. Bierer, and S.J. Burakoff. 1991. CD43, a molecule defective in Wiskott-Aldrich syndrome, binds ICAM-1. Nature. 354: 233-235 [Medline]. |
21. | Marlin, S.D., and T.A. Springer. 1987. Purified intercellular adhesion molecule-1 (ICAM-1) is a ligand for lymphocyte function-associated antigen 1 (LFA-1). Cell. 51: 813-819 [Medline]. |
22. |
Kuijpers, T.W.,
M. Hoogerwerf,
K.C. Kuijpers,
B.R. Schwartz, and
J.M. Harlan.
1992.
Cross-linking of sialophorin (CD43) induces neutrophil aggregation in a CD18-dependent and a CD18-independent way.
J. Immunol.
149:
998-1003
|
23. | Picker, L.J., R.A. Warnock, A.R. Burns, C.M. Doerschuk, E.L. Berg, and E.C. Butcher. 1991. The neutrophil selectin LECAM-1 presents carbohydrate ligands to the vascular selectins ELAM-1 and GMP-140. Cell. 66: 921-933 [Medline]. |
24. |
Berlin, C.,
R.F. Bargatze,
J.J. Campbell,
U.H. von Andrian,
M.C. Szabo,
S.R. Hassien,
R.D. Nelson,
E.L. Berg,
S.L. Erlandsen, and
E.C. Butcher.
1995.
![]() |
25. | Moore, K.L., K.D. Patel, R.E. Bruehl, L. Fugang, D.A. Johnson, H.S. Lichenstein, R.D. Cummings, D.F. Bainton, and R.P. McEver. 1995. P-selectin glycoprotein ligand-1 mediates rolling of human neutrophils on P-selectin. J. Cell Biol. 128: 661-671 [Abstract]. |
26. |
Axelsson, B.,
R. Yoouseffi-Etemad,
S. Hammarström, and
P. Perlmann.
1988.
Induction of aggregation and enhancement
of proliferation and IL-2 secretion in human T cells by antibodies to CD43.
J. Immunol.
141:
2912-2917
|
27. | Nong, N.H., E. Remold-O'Donnell, T.W. LeBien, and H.G. Remold. 1989. A monoclonal antibody to sialophorin (CD43) induces homotypic adhesion and activation of human monocytes. J. Exp. Med. 170: 259-267 [Abstract]. |
28. |
Manjunath, N.,
R.S. Johnson,
D.E. Staunton,
R. Pasqualini, and
B. Ardman.
1993.
Targeted disruption of CD43 gene enhances T lymphocyte adhesion.
J. Immunol.
151:
1528-1534
|
29. | De Smet, W., H. Walter, and L. Van Hove. 1993. A new CD43 monoclonal antibody induces homotypic aggregation of human leukocytes through a CD11a/CD18 dependent and independent mechanism. Immunology. 79: 46-54 [Medline]. |
30. |
Sanchez-Mateos, P.,
M.R. Campanero,
M.A. del Pozo, and
F. Sanchez-Madrid.
1995.
Regulatory role of CD43 leukosialin on integrin-mediated T-cell adhesion to endothelial
and extracellular matrix ligands and its polar redistribution to
a cellular uropod.
Blood.
86:
2228-2239
|
31. | Hernandez-Caselles, T., M. Martinez-Esparza, A.I. Lazarovits, and P. Aparicio. 1996. Specific regulation of VLA-4 and alpha 4 beta 7 integrin expression on human activated T lymphocytes. J. Immunol. 156: 3668-3677 [Abstract]. |
32. | Howell, D.N., V. Ahuja, L. Jones, O. Blow, and F.P. Sanfilippo. 1994. Differential expression of CD43 (leukosialin, sialophorin) by mononuclear phagocyte populations. J. Leukoc. Biol. 55: 536-544 [Abstract]. |
33. | Lopez, S., L. Halbwachs-Mercarelli, P. Ravaud, G. Bessou, M. Dougados, and F. Porteu. 1995. Neutrophil expression of tumour necrosis factor receptors (TNF-R) and of activation markers (CD11b, CD43, CD63) in rheumatoid arthritis. Clin. Exp. Immunol. 101: 25-32 [Medline]. |
34. | Woodman, R.C., F.L. Johnston, D. Teoh, and M. Maric. 1997. Shedding of neutrophil CD43 (leukosialin) requires a protease(s) localized to secondary granules. Blood. 90: 14a . |