| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Cell Processing, Institute of Medical Science, University of Tokyo, Tokyo, Japan
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Umbilical cord blood (CB) has been used as a source of hematopoietic
stem cells in patients with HLA-identical or HLA-disparate sibling or
unrelated donors, and there appears to be a reduced incidence and
severity of acute or extensive chronic GVHD in CBT when compared with
results obtained using BM (1, 2). Because the successful outcome of
allogeneic BMT is significantly limited by the risk of GVHD, this
feature of CBT could prove to be valuable for its use in stem cell
reconstitution. We (5) and others (6) previously reported that CBTCs
consist of a large subpopulation of
CD45RA+CD45RO--expressing cells and a small
population of CD45RA-CD45RO+-expressing cells,
while PBTCs and BMTCs exhibit similar ratios of
CD45RA+CD45--expressing cells and
CD45RA-CD45RA+-expressing cells, indicating
that CBTCs exhibit an immature state. Furthermore, CBTCs exhibit
impaired expression of cell surface molecules, including IL-2R
complexes, IL-12Rß1, and CD154 (CD40L), and defective effector
functions, including secretion of IL-4 and IL-12, IFN-
, and TNF-
following activation (5, 6, 7, 8, 9, 10, 11, 12). Although these dysregulations of CBTCs
may account for the reduced incidence of severe GVHD observed in CBT,
the precise mechanisms responsible for defective tissue destruction
leading to low incidence of severe GVHD in CBT is not clear.
Engagement of TCR/CD3 complexes by appropriate MHC/peptide
ligands or their respective mAbs initiate an elaborate biochemical
program that ultimately results in the induction of a variety of TC
functions (13, 14, 15, 16). One of the earliest detectable steps in this
cascade is the phosphorylation of the TCR-
and CD3, 
- and
-chain on specific sites within their cytoplasmic domains, known as
immunoreceptor tyrosine-based activation motifs (ITAM), by associated
protein tyrosine kinases (PTKs) (13, 14, 15, 16). Currently, the specific PTKs
known to associate, either directly or indirectly, with the TCR/CD3
complexes, are p56lck and
p59fyn, which belong to the Src family and
Syk family members ZAP-70 and Syk (13, 14, 15, 16). The current model proposes
that proximal signaling via TCR/CD3 complexes is dependent on the
sequential activation of these two PTK families (13, 14, 15, 16). Cross-linking
of the TCR/CD3 complexes is thought to result in the activation of Src
family PTKs, which phosphorylate ITAM of TCR- and CD3 complexes
(13, 14, 15, 16). This in turn allows the recruitment and subsequent
phosphorylation of ZAP-70 leading to its enzymatic activation.
Following initial PTK activation, other biochemical signals are
generated, including those derived from the phosphatidylinositol
pathway and Ras/Rac/Rho-activated cascades of a family of
mitogen-activated protein kinases (MAPKs) (13, 14, 15, 16).
MAPKs are activated following engagement of a variety of cell surface receptors via dual tyrosine and threonine phosphorylation and are thought to be involved in various cellular responses (17, 18, 19, 20). The various members of the MAPK families differ in their substrate specificity and are activated by distinct upstream regulators and extracellular stimuli (17, 18, 19, 20). Currently, the MAPK family is comprised of three subfamilies, namely: 1) the extracellular signal-related kinase (ERK) subfamily, including p42mapk/erk2 and p44mapk/erk1; 2) the stress-activated protein kinase/c-jun N-terminal kinase (SAPK/JNK) subfamily, including the p46 SAPK/JNK and p54 SAPK/JNK isoforms and their variants; and 3) the p38mapk subfamily (17, 18, 19, 20). Previous studies have shown that blockage in the MAPKs pathway leads to anergic states in several T cell clones (21, 22, 23). Although the cascade of signaling events that occur upon engagement of the TCR/CD3 complexes in mature TCs peripherally and in lymph nodes and several T cell clones have been demonstrated in previous studies, much less is known about the TCR/CD3 complex-mediated molecular events in CBTCs.
To examine the involvement of properties of TCs in the low incidence of GVHD in CBT, we investigated CD3- and CD28-mediated functional properties and signaling events in CBTCs. We demonstrate that dual stimulation of PBTCs and BMTCs with mAb to CD3 and CD28 induced FasL as well as CD25 and CD154, whereas CBTCs failed to induce these molecules following stimulation. Furthermore, we showed that engagement of CD3 and CD28 with their respective mAbs induced aberrant PTK-dependent cascades in terms of tyrosine phosphorylation and enzymatic activation of ERK2, SAPK/JNK, and p38mapk, as well as p56lck and ZAP-70. Our results suggest that CD3- and CD28-mediated signaling events blockage in CBTCs may be responsible for dysregulation of the Fas/FasL system, which may be responsible for the reported low incidence of severe GVHD in CBT.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The medium used was RPMI 1640 supplemented with 2 mM
L-glutamine, 50 µg/ml streptomycin, 50 U/ml penicillin,
and 10% heat-inactivated FCS. Granulocyte-macrophage CSF (GM-CSF) was
kindly provided by Kirin Brewery (Tokyo, Japan). IL-2 and IL-4 were
purchased from PeproTech (London, U.K.). mAbs to CD3, CD28, and FasL
(clone NOK2) were purchased from PharMingen (San Diego, CA). Con A was
purchased from Sigma (St. Louis, MO). Metalloproteinase inhibitor
KB-R8301 was kindly provided by Kanebo (Osaka, Japan). Horseradish
peroxidase (HRP)-conjugated anti-phosphotyrosine mAb (clone RC20)
was purchased from Transduction Laboratories (Lexington, KY). Abs to
CD3, p56lck, and ZAP-70 were purchased from
Santa Cruz Biotechnology (Santa Cruz, CA). ERK2, SAPK/JNK, and
p38mapk immunoblotting kits, their kinase assay
kits, and HRP-conjugated secondary Abs were purchased from New England
Biolabs (Beverly, MA).
Preparation and culture of TCs
Samples of PB, BM, and umbilical CB were obtained according to institutional guideline with informed consent from all healthy volunteers. Mononuclear cells (MNCs) from each sample were obtained by Ficoll-Hypaque (Pharmacia Fine Chemicals, Uppsala, Sweden) density centrifugation, and purification of TCs was performed by E-rosetting (9). T cell preparations were typically >90% pure, as indicated by anti-CD3 mAb staining (Becton Dickinson, Mountain View, CA). Cells were either unstimulated or stimulated with a combination of immobilized mAbs to CD3 and CD28 (21, 22) in the presence or absence of 10 µM metalloproteinase inhibitor KB-R8301 (24, 25) for 16 h at 37°C, and cells were used for subsequent experiments. Con A blasts were prepared from PBMNCs by cultivation with 5 µg/ml of Con A and 10 ng/ml of IL-2 for 48 h, followed by incubation in the presence of IL-2 alone for 5 days (25). Dead cells were removed by gradient centrifugation using Histopaque 1083 (Sigma).
In vitro generation and culture of human dendritic cells (DCs)
DCs were generated from PBMNCs as described previously (26).
Briefly, PBMNCs were resuspended in culture medium and allowed to
adhere to 6-well plates (Costar, Cambridge, MA). After 2 h at
37°C, nonadherent cells were removed, and adherent cells (
90%
CD14+ cells) were cultured in 3 ml of medium supplemented
with GM-CSF (50 ng/ml) and IL-4 (250 ng/ml). After 7 days of culture,
DCs were harvested, washed, and used for subsequent experiments.
Flow cytometry
TCs were treated with 0.5% mouse serum (Dako, Glostrup, Denmark) for 15 min at 4°C to block the Fc receptor, and stained with FITC-conjugated anti-CD3 mAb (Becton Dickinson) and phycoerythin (PE)-conjugated anti-CD25 mAb (Becton Dickinson), PE-conjugated CD154 mAb (PharMingen), or biotin-conjugated FasL mAb (clone NOK2; PharMingen) followed by PE-conjugated avidin (Becton Dickinson). Cells were also stained with the corresponding FITC- and PE-conjugated isotype-matched mAbs (Becton Dickinson). Analysis of fluorescence staining was performed with a FACSCalibur flow cytometer (Becton Dickinson) and CELLQuest Software (Becton Dickinson).
Assay for alloMLR
TCs (105) were cultured with various concentrations of irradiated (15 Gy from a 137Cs source) allogeneic monocyte-derived DCs (102-105) (26). Thymidine incorporation was measured on day 5 by an 18-h pulse with 0.5 µCi/well of [3H]thymidine (1 µCi/well; Amersham Life Science, Buckinghamshire, U.K.) (26).
Cytotoxicity assay
Unstimulated or stimulated TCs (104-106) were cultured with Na251CrO4 (100 µCi/106 cells; New England Nuclear Life Science Products, Boston, MA)-labeled Con A blast (104) for 4 h at various E:T ratios (1:10–1:100) in the presence or absence of 10 µg/ml control IgG (cont. IgG; Sigma) or anti-FasL mAb (24, 25, 27, 28). The supernatants were harvested, radioactivity was counted, and percentage of specific lysis was calculated (27). Value of spontaneous release cpm was <10% of the total release cpm.
RT-PCR
RNA from each sample was isolated using Trizol LS reagent (Life Technologies, Gaithersburg, MD). The first strand cDNA kit (SuperScript Preamplication System; Life Technologies) was used to make cDNA from 5 µg of each RNA. Amplification of each cDNA was performed with a SuperTaq Premix kit (Sawady Technology, Tokyo, Japan) using specific primers (14).
Western blot analysis and immune complex kinase assay
TCs were starved in serum-free medium for 16 h at 37°C,
and subsequently kept for 4 h on ice to reduce the basal levels of
tyrosine phosphorylation of intracellular proteins. Cells (2 x
106) were untreated or stimulated with a combination of
immobilized mAbs to CD3 and CD28 for 5 min at 37°C, washed twice in
cold PBS, resuspended in 100 µl of lysis buffer (1% Nonidet P-40, 20
mM Tris-HCl (pH 8.0), 137 mM NaCl, 10% glycerol, 2 mM EDTA, 10 µg/ml
leupeptin, 10 µg/ml aprotinin, 1 mM PMSF, and 1 mM sodium
orthovanadate), and cell lysates were obtained. Total cell lysates or
the immunoprecipitates with Abs to CD3,
p56lck, or ZAP-70 (13, 14, 21, 22, 23) were
fractionated by 12% SDS-PAGE, transferred onto PVDF membranes
(Millipore, Bedford, MA), and probed with HRP-conjugated
anti-phosphotyrosine mAb (clone RC-20). Blots were visualized by
enhanced chemiluminescence (ECL) (New England Biolabs). To ensure
similar amounts of respective proteins in each sample, the same
membrane was stripped off, reprobed with stated Abs, and developed with
HRP-conjugated secondary Abs by ECL. For immune complex kinase assay,
the immunoprecipitates with Abs to p56lck or
ZAP-70 were washed three times with lysis buffer and twice with kinase
buffer before resuspending in 20 µl of kinase buffer containing 10
µM ATP (New England Biolabs), 5 µCi [-32P]ATP (New
England Nuclear Life Science Products), and 5 µg enolase (Sigma).The
mixtures were incubated at 30°C for 5 min, and the reactions were
terminated, separated by 12% SDS-PAGE, transferred onto PVDF
membranes, and subjected to autoradiography. Immunoblotting and in
vitro kinase assay of ERK2, SAPK/JNK, or
p38mapk were performed with their
respective kits according to the manufacturer’s instruction
manuals.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Engagement of TCR/CD3 complexes and adhesion/costimulatory
molecules with their respective counter ligand or mAbs results in
activation of signals that drive induction of various functions,
including secretion of several cytokines and expression of
adhesion/costimulatory molecules on their surface in mature TCs (13, 14, 21, 22, 23). Previous studies have shown that several functions were
impaired in CBTCs following various stimulations (5, 6, 7, 8, 9, 10, 11, 12). Therefore, we
examined the cell surface expression levels of CD3 and CD28 in PBTCs,
BMTCs, and CBTCs by flow cytometry using the respective mAbs. Flow
cytometric analysis revealed similar expression levels of CD3 and CD28
among PBTCs, BMTCs, and CBTCs (Fig. 1
A), and the ratio of the cell
subpopulations expressing CD3 and/or CD28 was not different in these TC
subsets (Fig. 1B).
|
). Engagement of both CD3 and CD28 by
specific mAbs induced significant cell surface expression of CD25 and
CD154 in PBTCs and BMTCs, although these cells had low expression
levels of CD25 and did not constitutively express CD154 in their normal
states. On the other hand, treatment of CBTCs with mAbs to both CD3 and
CD28 induced a lower expression level of CD25 compared with PBTCs and
BMTCs, whereas CD154 was not induced.
|
B), and these
results are concomitant with cell surface expression (Fig. 2A). On the other hand, ligation of CD3 and CD28 with their
respective mAbs in CBMCs failed to induce FasL transcript expression or
its product on the cell surface. These results indicate that CD3- and
CD28-mediated activation-associated phenotypic changes are impaired in
CBTCs. CBTCs exhibited selective low sensitivity for proliferative response in alloMLR
The in vitro proliferative responsiveness of PBTCs and CBTCs
generated in alloMLR have been previously reported. Most studies
comparing the ability of PBTCs and CBTCs to proliferate in response to
alloAg have been performed by using bulk cultures or sets of purified
TCs as responder cells and irradiated B cell lines as stimulator cells
at relatively high responder cell to stimulator cell ratios (R:S
ratios, 10:1) (27, 29). DCs have been shown to be unique professional
major APCs capable of stimulating resting TCs in the primary immune
response and are more potent APCs than monocytes/macrophages, B cells,
or their respective cell lines (26). Therefore, we cultured PBTCs or
CBTCs (105) with irradiated allogeneic monocyte-derived DCs
(102–105) to clarify the differences between
the proliferative responsiveness of PBTCs and CBTCs to alloAg (Fig. 3A). The capacity of CBTCs to
proliferate following stimulations with alloAg were significantly
weaker than those of PBTCs at lower stimulation levels (R:S ratios,
103:2 x 102), whereas comparable
responses to higher stimulation were observed (R:S ratios,
102:1). These results indicate that CBTCs possess
proliferative responsiveness to alloAg, although this sensitivity is
lower than that of PBTCs.
|
Previous studies have demonstrated a decrease in the cytotoxic
function of CBTCs generated by alloMLR compared with PBTCs (27).
However, there are conflicting reports that the cytotoxic activity of
CBTCs against alloAg-expressing cells is comparable to that of PBTCs
(30). To directly examine potential cytotoxic capacities, PBTCs or
CBTCs were unstimulated or stimulated with a combination of
anti-CD3 mAb plus anti-CD28 mAb, and the cytotoxicities of
these cells against allogeneic Con A blasts expressing functional Fas
on their cell surface (25) were examined. Treatment of PBTCs with a
combination of mAbs to CD3 and CD28 induced cytotoxicity against
allogeneic Con A blasts (Fig. 3B), which was partially
blocked by anti-FasL mAb (Fig. 3D), indicating that the
Fas/FasL system is involved in PBTC-mediated cytotoxicity. In contrast,
little or no cytotoxicity was induced in CBTCs following these
stimulations (Fig. 3, B and C). These results are
consistent with the deficient expression of inducible FasL (Fig. 2, A and B). These results indicate that CBTCs
impair the CD3- and CD28-mediated capacity of killing target cells via
Fas/FasL system.
Aberrant CD3- and CD28-mediated signaling events in CBTCs
FasL expression has been shown to be regulated by TCR/CD3
complex-mediated signaling events involving
p56lck, ZAP-70 and Ras signaling pathways in T
cell clones (13, 14, 15). However, CD3- and CD28-mediated signaling events
in CBTCs remains poorly understood. Therefore, we examined signaling
events involving PTK-mediated cascades triggered by CD3 and CD28 in
CBTCs. Dual stimulation with mAbs to CD3 and CD28 initiated tyrosine
phosphorylation of several intracellular proteins in PBTCs (Fig. 4A). On the other hand, a
similar pattern of tyrosine phosphorylation of several target proteins
was also observed in CBTCs following these stimulations, although the
degree of phosphorylation was significantly lower than that of PBTCs
(Fig. 4A).
|
. Fig. 4B shows that
ligation of CD3 and CD28 induced lower levels of tyrosine
phosphorylation of CD3 in CBTCs than PBTCs, even though the total
amounts of CD3 were equivalent.
Faith et al. (16) previously suggested that defective TCR stimulation
in anergized type 2 Th cells may correlate with abrogated
p56lck and ZAP-70 tyrosine kinase activities. To
further evaluate the role of p56lck and ZAP-70
in defective CD3- and CD28-mediated tyrosine phosphorylation events in
CBTCs, their tyrosine phosphorylation levels and kinase activities were
examined (Fig. 4, C and D). Unlike PBTCs, dual
stimulation of CBTCs with mAbs to CD3 and CD28 did not significantly
induce tyrosine phosphorylation and the up-regulation of tyrosine
kinase activities of p56lck and ZAP-70.
Recent studies have shown that blockage in the Ras/Raf/ERK2, SAPK/JNK,
and p38mapk pathway leads to anergic states in
mature TCs (21, 22, 23). To clarify the potential involvement of ERK2,
SAPK/JNK, and p38mapk in the functional
deficiencies in CBTCs, cells were unstimulated or stimulated with dual
stimulation using mAbs to CD3 and CD28, and the level of MAPKs
phosphorylation was assessed by immunoblotting with
antityrosine-phosphorylated MAPK mAbs (Fig. 5, A–C). Dual stimulation of
PBTC increased tyrosine phosphorylation of ERK2, SAPK/JNK, and
p38mapk compared with those of unstimulated
cells. On the other hand, dual stimulation with mAbs to CD3 and CD28
resulted in a significant reduction in the tyrosine-phosphorylated
forms of these MAPKs when compared with those of PBTCs. The total
amounts of these MAPKs were unchanged following stimulations in PBTCs
or CBTCs (Fig. 5, A–C).
|
, A–C). Indeed, the kinase assays clearly showed that
engagement of both CD3 and CD28 triggered activation of ERK2, SAPK/JNK,
and p38mapk in PBTCs. Conversely, dual
stimulation with mAbs to CD3 and CD28 resulted in lower kinase
activities of these MAPKs in CBTCs than those of PBTCs. These results
agree with the levels of the tyrosine phosphorylation forms of these
MAPKs (Fig. 5, A–C). These results indicate that CD3- and
CD28-mediated PTK-dependent signaling events are deficient in CBTCs. |
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
), which may be involved in the
lower incidence of severe GVHD in CBT.
|
, and TNF- by
donor-derived activated mature TCs may be involved in the development
of GVHD in allogeneic BMT (10, 11, 12). A series of previous studies have
shown CBTCs impaired capacity to produce these cytokine following
several stimulations (10, 11, 12). We (5) and others (7, 8, 9) have previously
reported that CBTCs exhibit low levels of IL-2R and IL-12R complexes on
their cell surface, and stimulation of these cells failed to induce
cell surface expression of CD154. On the other hand, previous studies
have shown that CBTCs exhibited similar proliferative capacity to PBTCs
in response to allostimulations when CBTCs or PBTCs were cultured with
irradiated allogeneic B cell lines at relatively high stimulation (R:S
ratios, 10:1) (27, 29). We showed that the proliferative response of
CBTCs was lower than that of PBTCs when CBTCs or PBTCs were cultured
with allogeneic DCs at lower stimulation (R:S ratios,
103:2 x 102) compared with PBTCs, whereas
similar proliferative capacities were observed at higher stimulation
(R:S ratios, 102:1) (Fig. 3A), suggesting that
CBTCs may exhibit lower sensitivity in response to alloAg, whereas
these cells may possess intrinsically similar proliferative capacity
compared with that of PBTCs. These phenomena imply that the defective
capacities of CBTCs to exhibit several functions, including secretion
of various cytokines, expression of adhesion/costimulatory molecules,
and proliferative responses to alloAg may contribute to low incidence
of GVHD, although the direct involvement of these deficiencies in
tissue destruction remains unclear.
The Fas/FasL system as well as perforin lytic pathway are believed to
be involved in donor-derived mature TC-mediated tissue damage in the
pathogenesis of GVHD in recipients (3, 24, 25, 28). We showed that
engagement of CD3 and CD28 by their respective mAbs induced FasL
transcript and its product on the cell surface in PBTCs and BMTCs (Fig. 2, A and B). Furthermore, dual stimulation of
PBTCs with mAbs to CD3 and CD28 induced cytotoxicity against allogeneic
Con A blasts (Fig. 3B), which was partially blocked by mAb
to FasL (Fig. 3C). These results suggest that the Fas/FasL
system and other killing mechanisms, such as the perforin lytic
pathway, may be involved in PBTC-mediated cytotoxicity (3, 4, 24, 25, 28). We also showed that CBTCs failed to induce cytotoxic capacity
against these target cells (Fig. 3, B and C).
These results are consistent with the deficient expression of inducible
FasL (Fig. 2, A and B) and the lack of
constitutive perforin expression in CBTCs (4). These results suggest
that the defective CD3- and CD28-induced capability of killing
allogeneic target cells via FasL-dependent or -independent manners may
be correlated with low incidence of tissue damage in GVHD in CBT.
Ligation of TCR/CD3 complexes and adhesion/costimulatory molecules with
their respective counter ligand induce various intracellular signaling
events leading to the induction of a variety of TC functions (13, 14, 15, 16).
We showed that dual stimulation of CBTCs induced lower tyrosine
phosphorylation of CD3, p56lck, and ZAP-70,
as well as MAPKs (ERK2, SAPK/JNK, and p38mapk)
and their enzymatic activation compared with those of PBTCs (Figs. 4 and 5). Also, Porcu et al. (29) recently reported that
alloAg-stimulated CBTCs were preferentially induced into a state of
anergy following restimulation, and this state may be associated with
defective activation of Ras. These phenomena imply that defective early
intracellular signaling leading to aberrant activation of
p56lck- and ZAP-70-mediated signaling events as
well as MAPK cascades may be involved in the molecular mechanism
underlying deficient CD3- and CD28-mediated functional changes,
including FasL expression in CBTCs.
The molecular mechanisms underlying CD3- and CD28-mediated defective signaling events in CBTCs remain unclear. It has been shown that the tyrosine phosphorylation states of the targeted proteins are regulated by their respective kinases and phosphatases (31, 32, 33, 34). We (31) and others (32, 33, 34) have previously suggested that a family of protein tyrosine phosphatases may exist to antagonize a large number of kinases, and these phosphatases may be involved in dominant negative signaling in certain cells. Furthermore, previous studies have shown that certain phosphatases specifically dephosphorylate several members of the MAPK families (35). Although the precise relationship between the defective signaling events and their respective phosphatases in CBTCs remains unknown, our data suggest that the downstream section of the CD3- and CD28-mediated signaling events may negatively regulate PTK-dependent cascades. Further study is necessary to examine this possibility.
In summary, our results provide possible reasons for an advantage of CB as a donor tissue in allogeneic CBT in terms of low frequencies of severe GVHD. Although we suggest that a defect in inducible FasL expression as well as other functional deficiencies in CBTCs may be contribute to the low frequency of severe GVHD in CBT, other mechanisms involving cells, such as B cells and NK cells, may also participate in these phenomena. Defining the precise mechanisms of immunological properties of CB may facilitate use of CB as a donor tissue for sibling and unrelated CBT.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
2 Address correspondence and reprint requests to Dr. Tsuneo A. Takahashi, Department of Cell Processing, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan. E-mail address:
3 Abbreviations used in this paper: BM, bone marrow; T, transplantation; CB, cord blood; allo, allogeneic; DCs, dendritic cells; ERK, extracellular signal-regulated kinase; L, ligand; GM-CSF, granulocyte-macrophage CSF; GVHD, graft-vs-host disease; HRP, horseradish peroxidase; MAPK, mitogen-activated protein kinase; MNC, mononuclear cell; PB, peripheral blood; PTK, protein tyrosine kinase; R:S ratios, responder cell to stimulator cell ratios; SAPK/JNK, stress-activated protein kinase/c-jun N-terminal kinase; TCs, T cells.
Received for publication October 22, 1998. Accepted for publication January 21, 1999.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
receptor chain on cord blood mononuclear cells. Blood 87:3344. production by neonatal T cells. J. Clin. Invest. 87:194.
, natural killer, and lymphokine-activated killer activity by IL-12 in cord blood mononuclear cells. Blood 88:945.. Proc. Natl. Acad. Sci. USA 94:13169.-induced activation of c-jun N-terminal kinase is mediated by TRAF-2. EMBO J. 16:1080.[Medline]
B and c-jun N-terminal kinase (JNK/SAPK) pathways at TNF receptor-associated factor 2. Proc. Natl. Acad. Sci. USA 94:9792. in mouse bone marrow-derived macrophages. J. Immunol. 159:4491.[Abstract]
RIIB1 activates Src homology 2-containing protein tyrosine phosphatase-1. J. Immunol. 161:2716.This article has been cited by other articles:
|
|
 |
|
  Y. J. Ha, Y.-C. Mun, C.-M. Seong, and J. R. Lee Characterization of phenotypically distinct B-cell subsets and receptor-stimulated mitogen-activated protein kinase activation in human cord blood B cells J. Leukoc. Biol., December 1, 2008; 84(6): 1557 - 1564. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Q. Tang, B. Grzywacz, H. Wang, N. Kataria, Q. Cao, J. E. Wagner, B. R. Blazar, J. S. Miller, and M. R. Verneris Umbilical Cord Blood T Cells Express Multiple Natural Cytotoxicity Receptors after IL-15 Stimulation, but Only NKp30 Is Functional J. Immunol., October 1, 2008; 181(7): 4507 - 4515. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Kobayashi, K. Ohnuma, M. Uchiyama, K. Iino, S. Iwata, N. H. Dang, and C. Morimoto Association of CD26 with CD45RA outside lipid rafts attenuates cord blood T-cell activation Blood, February 1, 2004; 103(3): 1002 - 1010. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Jullien, R. Q. Cron, K. Dabbagh, A. Cleary, L. Chen, P. Tran, P. Stepick-Biek, and D. B. Lewis Decreased CD154 expression by neonatal CD4+ T cells is due to limitations in both proximal and distal events of T cell activation Int. Immunol., December 1, 2003; 15(12): 1461 - 1472. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Sato, H. Kawasaki, C. Morimoto, N. Yamashima, and T. Matsuyama An Abortive Ligand-Induced Activation of CCR1-Mediated Downstream Signaling Event and a Deficiency of CCR5 Expression Are Associated with the Hyporesponsiveness of Human Naive CD4+ T Cells to CCL3 and CCL5 J. Immunol., June 15, 2002; 168(12): 6263 - 6272. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Sato, H. Kawasaki, H. Nagayama, M. Enomoto, C. Morimoto, K. Tadokoro, T. Juji, and T. A. Takahashi Signaling events following chemokine receptor ligation in human dendritic cells at different developmental stages Int. Immunol., February 1, 2001; 13(2): 167 - 179. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Sato, H. Kawasaki, H. Nagayama, M. Enomoto, C. Morimoto, K. Tadokoro, T. Juji, and T. A. Takahashi Chemokine Receptor Expressions and Responsiveness of Cord Blood T Cells J. Immunol., February 1, 2001; 166(3): 1659 - 1666. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Dardalhon, S. Jaleco, C. Rebouissou, C. Ferrand, N. Skander, L. Swainson, P. Tiberghien, H. Spits, N. Noraz, and N. Taylor Highly efficient gene transfer in naive human T cells with a murine leukemia virus-based vector Blood, August 1, 2000; 96(3): 885 - 893. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Nagayama, K. Sato, H. Kawasaki, M. Enomoto, C. Morimoto, K. Tadokoro, T. Juji, S. Asano, and T. A. Takahashi IL-12 Responsiveness and Expression of IL-12 Receptor in Human Peripheral Blood Monocyte-Derived Dendritic Cells J. Immunol., July 1, 2000; 165(1): 59 - 66. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Sato, H. Kawasaki, H. Nagayama, M. Enomoto, C. Morimoto, K. Tadokoro, T. Juji, and T. A. Takahashi TGF-{beta}1 Reciprocally Controls Chemotaxis of Human Peripheral Blood Monocyte-Derived Dendritic Cells Via Chemokine Receptors J. Immunol., March 1, 2000; 164(5): 2285 - 2295. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
