| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
,
Departments of
*
Microbiology and
Internal Medicine, University of Iowa, and
Veterans Affairs Medical Center, Iowa City, IA 52242
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
B
(reviewed in Ref. 3).
Previously, we examined the contribution of TRAF2 to the CD40-mediated
induction of IgM secretion and found that induced overexpression of a
truncated, dominant-negative (DN) mutant TRAF2 inhibits this function
by 
50% (4). Interestingly, our earlier
structure-function studies of CD40 signaling to B cells had shown that
mutations in the CD40 cytoplasmic domain that prevent TRAF2 binding do
not decrease CD40-mediated IgM production (5), but DNTRAF2
expression also inhibits IgM secretion induced by these CD40 mutants
(4). A potential explanation of these findings is that
CD40-induced IgM secretion involves at least one other TRAF2-binding
member of the TNFR superfamily and expression of DNTRAF2 is exerting
its effect via this second receptor. We hypothesized that this second
receptor might be CD120a and/or CD120b. The present study was designed
to test this hypothesis.
We show here that TNF produced by CD40-stimulated B cells triggers signaling to the B cells through CD120b and that this signaling is an important component of CD40-mediated IgM production. Although both CD120b and CD40 interact directly with TRAF2 in B cells, and although direct TRAF2-CD40 binding is required for other CD40 functions (3), activation of IgM secretion by CD40 does not require CD40-TRAF2 binding. In contrast, CD120b-mediated IgM secretion requires TRAF2, and this TRAF2 signal cannot be provided by CD40. Our results thus demonstrate that specific TRAF functions in particular cell types can be markedly influenced by the receptor signaling complexes with which the TRAF interacts.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The mouse B cell line CH12.LX and transfectants expressing human
CD40 (hCD40) molecules and isopropylthio-
-D-galactoside
(IPTG)-inducible DNTRAF2 (aa 87–501 of mouse TRAF2 (mTRAF2) with an
amino-terminal FLAG tag) have been described (4).
The mouse B cell line M12.4.1 has been previously described
(6). J774 cells were from the American Type Culture
Collection (Manassas, VA). T-depleted mouse C57BL/6 splenocytes were
prepared as previously described (7). In some experiments,
small, high-density (resting) B lymphocytes were purified from the
splenocytes using Percoll density gradient centrifugation. All mouse
cells were maintained in RPMI 1640 containing 10% FCS (HyClone, Logan,
UT), 10 µM 2-ME, and antibiotics. In cells stably transfected with
inducible DNTRAF2, induction was accomplished by incubating the
cells with 100 µM IPTG for 15 h before stimulation of the cells
through CD40. Sf9 insect cells and Sf9 cells expressing mCD154 have
been described previously (7, 8).
DNA constructs
A cDNA construct coding for a chimeric hCD40-CD120b molecule was prepared using overlap extension PCR (9). The template for the external hCD40 domain was a previously reported hCD40 expression plasmid (5). The cDNA prepared from the mouse macrophage cell line J774 was used as template for the transmembrane and cytoplasmic portions of CD120b. Sequences of the PCR primers used in making the hCD40-CD120b hybrid were as follows: 5'-aagtcgacgcctcgctcgggcgcca-3', 5'-caattggaagagagatgccacctcgcagccgatcctgggg-3', 5'-ccccaggatcggctgcgaggtggcatctctcttccaattg-3', and 5'-tttctagatgtcaggggtcaggccactttgac-3'. The completed PCR products were ligated into the mammalian expression vector pRSV.5(neo) (10).
Transfections
Stable transfections of mouse B cell lines were conducted using electroporation as previously described (11).
Reagents
IPTG was purchased from Life Technologies (Gaithersburg, MD). Enbrel (Immunex, Seattle, WA) was obtained from the University of Iowa Hospital Pharmacy. All other reagents were purchased from Sigma-Aldrich (St. Louis, MO).
Antibodies
The 1C10 hybridoma (anti-mCD40, rat IgG2a) (12) was provided by Dr. F. Lund (Trudeau Institute, Saranac Lake, NY). The mAb EM-95.3 (anti-mouse IgE, rat IgG2a isotype control) (13) was a gift from Dr. T. Waldschmidt (University of Iowa, Iowa City, IA). The G28-5 (anti-hCD40) hybridoma was from the American Type Culture Collection. MOPC-21 (mouse IgG1 isotype control) was obtained from Sigma-Aldrich. The anti-mouse TNF Abs MP6-XT3 and MP6-XT22 (rat IgG1) (14) were kindly provided by Dr. J. Harty (University of Iowa). Purified hamster IgG (clone G235-2356), anti-mCD120a (55R-170), and mCD120b (TR75-32) mAbs were purchased from BD PharMingen (San Diego, CA). Polyclonal rabbit anti-TRAF2 was obtained from MBL (Nagoya, Japan). Polyclonal rabbit anti-TRAF3 was from purchased Santa Cruz Biotechnology (Santa Cruz, CA). Sheep polyclonal anti-hCD40 Ab has been described elsewhere (2). Peroxidase-labeled goat anti-rabbit IgG Ab was obtained from Bio-Rad (Hercules, CA) and peroxidase-labeled rabbit anti-sheep IgG was obtained from Upstate Biotechnology (Lake Placid, NY). For IgM ELISAs, goat anti-mouse IgM (Jackson ImmunoResearch Laboratories, West Grove, PA) was used for plate coating, alkaline phosphatase-conjugated goat anti-mouse IgM (Southern Biotechnology Associates, Birmingham, AL) for detection, and TEPC-183 (Sigma-Aldrich) for the standard.
TNF assays
ELISA plates were coated overnight at 4°C with anti-mouse TNF (clone G281-2626, 5 µg/ml, 100 µl/well; BD PharMingen) in 0.1 M borate (pH 6.0). Plates were blocked for 2 h at room temperature with B cell culture medium. Cells were then added to the plates (1 x 106 splenocytes or 5 x 105 CH12.LX cells/well) and stimulated for 3 h at 37°C with mCD154-bearing Sf9 cells or control Sf9 cells (1 Sf9 cell per 10 B cells) in a final volume of 200 µl. Recombinant TNF standards (0–2000 pg/ml; Endogen, Woburn, MA) in B cell culture medium (200 µl/well) were included in each plate and incubated for the same 3-h period. ELISA plates were then washed with PBS containing 0.05% Tween 20 (PBST). Secondary Ab (clone MP6-XT3-biotin; BD PharMingen) diluted in PBST containing 0.5% BSA was then added to each well (2 µg/ml; 100 µl/well), and the plates were incubated overnight at 4°C. Plates were washed and then incubated for 1 h at room temperature with streptavidin-HRP diluted in PBST containing 0.5% BSA (0.125 µg/ml; 100 µl/well). After washing the plates with PBST, 100 µl of substrate solution (0.05 M Na2HPO4, 0.025 M citric acid, 1 mg/ml o-phenylenediamine, 0.012% H2O2, pH 5.0) was added to each well and incubated for 5–10 min at room temperature. To stop color development, 100 µl of 0.67 M sulfuric acid was added to each well. OD of each well at 490 nm was determined using a microtiter plate reader.
IgM secretion assays
IgM secretion by CH12.LX cells was measured by hemolytic plaque
assay, as previously described (15). Briefly, cells were
cultured for 72 h with various stimuli, and then the viable cells
were counted by trypan blue exclusion. The B cells were mixed with
SRBCs and guinea pig complement, transferred to chamber slides, and
incubated for 30 min at 37°C. During this incubation, IgM secreted
by activated B cells binds to surrounding SRBCs (expressing the Ag for
which CH12.LX IgM is specific: phosphatidylcholine (16))
and fixes complement, causing the red cells to lyse. Zones of clearing
or "plaques" surrounding activated B cells were counted using a
low-power microscope. Results are presented as the ratio of plaque
forming cells to viable cells. To examine IgM secretion by T-depleted
splenocytes, cells (2.5 x 105/ml) were
preincubated for 30 min at 37°C with 10 µg/ml anti-TNF
(MP6-XT3), anti-CD120a, anti-CD120b, Enbrel, or isotype control
Abs, and then stimulated for 3 days with 5 µg/ml anti-mCD40
(1C10) or an isotype control mAb (EM95). Supernatants were tested for
IgM by ELISA. As described previously (15, 17), CH12.LX
does not express detectable levels of surface CD32, and thus intact
mouse IgG Abs do not have CD32-specific effects on these cells.
Detection of CD120a and CD120b mRNA
RNA was isolated from 5 x 106 CH12.LX, M12.4.1, or J774 cells using an RNA extraction kit (RNeasy; Qiagen, Valencia, CA). The cDNA was generated from the RNA using reverse transcriptase (Promega, Madison, WI) and a poly(T) oligonucleotide primer. The cDNA was then amplified by PCR using primers specific for the transmembrane and cytoplasmic domains of CD120a (5'-gttgtctgtggtccccaggactcaggtactg-3'; 5'-aatctagacttcctaaggttgtgggtgtggct-3'), CD120b (5'-ccccaggatcggctgcgaggtggcatctctcttccaattg-3'; 5'-tttctagatgtcaggggtcaggccactttgac-3'), or GAPDH (as a positive control) (18).
Immunoprecipitations
CH12.LX cells (1 x 107) stably
transfected with hCD40 or hCD40-CD120b were stimulated in 1 ml of
culture medium for 15 min (37°C) with 10 µg of anti-hCD40 to
induce association of TRAF molecules with the receptors. The cells were
pelleted by centrifugation, resuspended in 400 µl of lysis buffer (60
mM n-octyl -D-glucopyranoside, 1%
Triton X-100, 0.1% SDS, 20 mM Tris (pH 7.5), 150 mM NaCl, 50 mM
-glycerophosphate, 50 µg/ml PMSF, 50 µg/ml aprotinin, 10 µg/ml
leupeptin, and 10 µg/ml pepstatin A), and sonicated (on ice) with a
probe sonicator (Branson Ultrasonics, Danbury, CT) to reduce viscosity.
After a 15-min incubation on ice, insoluble debris was pelleted by
centrifugation and discarded. Protein G-Sepharose beads (10 µl of a
50% suspension) were added to the supernatant, which was then
incubated on a rotating mixer at 4°C for 2 h. The beads were
washed several times with lysis buffer containing 400 mM NaCl and then
analyzed by SDS-PAGE and Western blotting. Peroxidase-labeled Abs were
visualized on Western blots using a chemiluminescent detection reagent
(Pierce, Rockford, IL).
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
22, containing a 22-aa cytoplasmic truncation,
retains a wild-type ability to stimulate IgM secretion in the mouse B
cell line CH12.LX. Interestingly, unlike full-length hCD40, hCD4022
binds TRAF2 only weakly, if at all (4). TRAF2 is one
member of a family of intracellular proteins that appear to function as
adapter molecules, linking TNFR family members to downstream signaling
pathways. Although TRAF2 has been implicated in the CD40-mediated
activation of NF-B and c-Jun NH2-terminal
kinase (JNK) (20), our results with hCD4022 indicate
that a direct interaction between CD40 and TRAF2 is not required for
activation of IgM secretion by CD40. However, in cell lines stably
transfected with inducible TRAF2 or DNTRAF2, overexpression of the
former augments CD40-mediated IgM secretion, whereas expression of the
latter attenuates IgM production (4). These effects are
observed even if cells are stimulated through hCD4022, suggesting
that another TRAF2-binding receptor contributes to the IgM secretion
initiated by CD40 signaling.
Because TNF has been shown to promote Ab production by B cells in vitro
(21) and in vivo (22) and because TRAF2
interacts with both TNFRs, we considered the possibility that one or
both of these receptors is responsible for the augmentation of
CD40-mediated IgM secretion. Stimulation of CH12.LX cells or small
resting splenic B lymphocytes with CD154-expressing insect cells
resulted in the rapid production of TNF (Fig. 1
). Consistent with the hypothesis that
one of the TNFRs augments CD40-stimulated Ab secretion, stimulation of
CH12.LX cells with a saturating amount of exogenous TNF activated IgM
secretion to approximately one-half the level induced by CD40
engagement (Fig. 2A). To
confirm that the amount of TNF produced in response to CD40
stimulation is sufficient to augment IgM secretion, we also examined
IgM production by CD40-stimulated CH12.LX cells in the presence or
absence of neutralizing anti-TNF Abs. Anti-TNF Abs reduced by
50% the number of Ab-secreting cells that otherwise develop as the
result of CD40 stimulation (Fig. 2A). Similarly,
anti-TNF or the soluble TNFR drug Enbrel inhibited CD40-stimulated
IgM secretion by T cell-depleted mouse splenocytes (Fig. 2B).
|
|
). CD120a gene
expression, although detected in the mouse macrophage cell line J774,
was not detected in CH12.LX cells or in a second mouse B cell line,
M12.4.1. Consistent with these findings, unstimulated human B cells
have been reported to express CD120b, but little or no CD120a
(23, 24). Stimulation of CH12.LX or M12.4.1 cells through
CD40 for 2 or 6 h, respectively, did not result in detectable
up-regulation of CD120a mRNA (data not shown).
|
A).
Interestingly, the coprecipitation of TRAF2 with the hybrid appeared to
be more efficient than with hCD40. Stimulation of stably transfected
CH12.LX cells through the hCD40-CD120b hybrid resulted in levels of Ab
secretion similar to that achieved using rTNF as a stimulus (Fig. 4B). A similar hybrid molecule with the cytoplasmic domain
of CD120a did not induce IgM secretion when stably expressed at similar
levels on CH12.LX cells (data not shown). Furthermore, we found that
the CD40-mediated activation of IgM secretion by freshly isolated mouse
splenocytes was inhibited by a neutralizing anti-CD120b mAb, but
not by a similar anti-CD120a mAb (Fig. 4C).
|
A), but did inhibit Ab
secretion by 50% (Fig. 5, B and C). Anti-TNF
inhibited IgM secretion to a similar extent but, significantly, did not
enhance the inhibition mediated by DNTRAF2 (Fig. 5B).
DNTRAF2 induction almost completely abrogated TNF-induced IgM
production (Fig. 5C). Together, these observations indicate
that anti-TNF and DNTRAF2 block the same step in the activation of
IgM secretion: CD120b signaling.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
B). There are likely to be a number of factors that contribute to the ability of TRAFs, as illustrated here, to perform differently when associated with distinct receptors. First, each well-characterized member of the rapidly growing TNFR superfamily binds to TRAF molecules, but each binds a distinct and not completely overlapping set of TRAFs. Thus, CD40 in B cells is reproducibly found to bind TRAFs 2, 3, and 6 directly and TRAF1 via heterodimerization with TRAF2. Binding to TRAF5 has been shown by two-hybrid yeast analysis and transient overexpression in transformed epithelial cells, but this has not yet been confirmed in B cells (3). CD120b also binds TRAF2 and TRAF1, but it does not associate with TRAFs 3, 5, or 6 (20). It seems a reasonable prediction that the presence of additional TRAFs in a signaling complex influences the ultimate function of each TRAF. For example, because TRAF3 binds to CD40 at a site largely overlapping that of TRAF2 and has been implicated as a potential negative regulator of signaling in B cells (4), it is quite likely that the close proximity of TRAF3 in a receptor complex affects TRAF2 function. Another difference between individual receptor-TRAF interactions is their avidity. TRAF2 and TRAF3 both bind robustly to CD40 in B cells, but the association of TRAF2 with a virally encoded transforming protein that mimics CD40, LMP1, is much weaker. Interestingly, association with CD40 stimulates degradation of TRAF2, but association with LMP1 expressed in the same B cells does not, a difference that may be explained in part by weaker binding and which may contribute to the amplified signaling and transforming properties of the viral protein (26). It is also likely that TRAFs exhibit distinct functional properties in distinct cell types, even when binding to the same receptor.
The TRAF2-dependent signaling pathway activated by CD120b remains to be
identified. Previous work indicates that TRAF2 is potentially involved
in activating both JNK and NF-B (3). However, both of
these signals are supplied to CH12.LX cells by CD40 engagement
(19, 27), and because CD40 signaling cannot substitute for
CD120b signals in our experiments, it is unlikely that the critical
CD120b signal is mediated by either JNK or NF-B. In addition, we
have been unable to detect significant activation of either JNK or
NF-B in CH12.LX cells stimulated with TNF or through engagement of
hCD40-CD120b (data not shown). Together, our results demonstrate that
the TNFR family member dictates the signaling pathway with which TRAF2
associates. The receptor may accomplish this by inducing subtle changes
in TRAF2 conformation or through the recruitment of additional proteins
that interact with TRAF2 in the signaling complex.
Our results also support the possibility that CD120b contributes to the activation of humoral immune responses, because neutralizing Abs to TNF markedly reduced CD40-mediated IgM production by both normal splenic B cells and CH12.LX. Similar results have been reported in human B cells (21). However, it has also been reported that CD120b-deficient mice do not show a substantial defect in the IgM response to SRBCs (28); responses to other Ags have not been reported. This shows that, at least in some situations, IgM responses are not highly dependent upon CD120b signaling. However, it is possible that the absence of CD120b from the earliest stages of embryogenesis can be compensated by adjustments to other signaling pathways, because the redundancy of the mammalian immune system is well documented. Additionally, the immune response to the model Ag SRBC may not be representative of IgM responses to all T-dependent Ags. In this regard, it is interesting to note that CD120b-/- mice have much lower survival rates than wild-type mice after infection with ectromelia virus (29). Although the basis of this increased mortality remains to be determined, it would be of interest to examine IgM responses to virus in these mice.
In summary, we have shown that TRAF molecules can function in CD40 signaling to B cells, not only by direct binding to CD40, but also by association with other receptors that participate in CD40-mediated effects. We believe that this concept is very likely to apply to additional TRAF-receptor interactions and illustrates the multiple ways in which this family of cytoplasmic adapter proteins can regulate signaling.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
2 Address correspondence and reprint requests to Dr. Gail A. Bishop, Department of Microbiology, University of Iowa, 3-570 BSB, Iowa City, IA 52242. E-mail address: gail-bishop{at}uiowa.edu
3 Abbreviations used in this paper: TRAF, TNFR-associated factor; DN, dominant negative; h, human; IPTG, isopropylthio--D-galactoside; m, mouse; JNK, c-Jun NH2-terminal kinase.
Received for publication November 1, 2001. Accepted for publication February 1, 2002.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
1 and 
Ig gene expression in murine B cells: IL-4 and the CD40 ligand-CD40 interaction provide distinct but synergistic signals. J. Immunol. 155:5637.[Abstract]
B activation in B lymphocytes. J. Immunol. 159:4898.[Abstract]
: autocrine and paracrine cytokines involved in B cell function. J. Immunol. 146:3462.[Abstract]
by an adenovirus-encoded soluble fusion protein extends transgene expression in the liver and lung. J. Virol. 73:5098. facilitates induction of CD80 (B7-1) and CD54 on human B cells by activated T cells: complex regulation by IL-4, IL-10, and CD40L. Cell. Immunol. 161:226.[Medline]
This article has been cited by other articles:
|
|
 |
|
  A. L. Peters, R. M. Plenge, R. R. Graham, D. M. Altshuler, K. L. Moser, P. M. Gaffney, and G. A. Bishop A novel polymorphism of the human CD40 receptor with enhanced function Blood, September 1, 2008; 112(5): 1863 - 1871. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. M. Rahhal, T. J. Vanden Bush, M. K. McLendon, M. A. Apicella, and G. A. Bishop Differential effects of Francisella tularensis lipopolysaccharide on B lymphocytes J. Leukoc. Biol., October 1, 2007; 82(4): 813 - 820. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. L. Rowland, M. M. Tremblay, J. M. Ellison, L. L. Stunz, G. A. Bishop, and B. S. Hostager A Novel Mechanism for TNFR-Associated Factor 6-Dependent CD40 Signaling J. Immunol., October 1, 2007; 179(7): 4645 - 4653. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. E. Munroe, J. L. Arbiser, and G. A. Bishop Honokiol, a Natural Plant Product, Inhibits Inflammatory Signals and Alleviates Inflammatory Arthritis J. Immunol., July 15, 2007; 179(2): 753 - 763. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. E. Munroe and G. A. Bishop A Costimulatory Function for T Cell CD40 J. Immunol., January 15, 2007; 178(2): 671 - 682. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Xie, B. S. Hostager, M. E. Munroe, C. R. Moore, and G. A. Bishop Cooperation between TNF Receptor-Associated Factors 1 and 2 in CD40 Signaling J. Immunol., May 1, 2006; 176(9): 5388 - 5400. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. M. Andrade, M. Wessendarp, J.-A. C. Portillo, J.-Q. Yang, F. J. Gomez, J. E. Durbin, G. A. Bishop, and C. S. Subauste TNF Receptor-Associated Factor 6-Dependent CD40 Signaling Primes Macrophages to Acquire Antimicrobial Activity in Response to TNF-{alpha} J. Immunol., November 1, 2005; 175(9): 6014 - 6021. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. D. Morrison, W. Reiley, M. Zhang, and S.-C. Sun An Atypical Tumor Necrosis Factor (TNF) Receptor-associated Factor-binding Motif of B Cell-activating Factor Belonging to the TNF Family (BAFF) Receptor Mediates Induction of the Noncanonical NF-{kappa}B Signaling Pathway J. Biol. Chem., March 18, 2005; 280(11): 10018 - 10024. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. E. Munroe and G. A. Bishop Role of Tumor Necrosis Factor (TNF) Receptor-associated Factor 2 (TRAF2) in Distinct and Overlapping CD40 and TNF Receptor 2/CD120b-mediated B Lymphocyte Activation J. Biol. Chem., December 17, 2004; 279(51): 53222 - 53231. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Xie, B. S. Hostager, and G. A. Bishop Requirement for TRAF3 in Signaling by LMP1 But Not CD40 in B Lymphocytes J. Exp. Med., March 1, 2004; 199(5): 661 - 671. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. A. Haxhinasto and G. A. Bishop Synergistic B Cell Activation by CD40 and the B Cell Antigen Receptor: ROLE OF B LYMPHOCYTE ANTIGEN RECEPTOR-MEDIATED KINASE ACTIVATION AND TUMOR NECROSIS FACTOR RECEPTOR-ASSOCIATED FACTOR REGULATION J. Biol. Chem., January 23, 2004; 279(4): 2575 - 2582. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. S. Hostager, S. A. Haxhinasto, S. L. Rowland, and G. A. Bishop Tumor Necrosis Factor Receptor-associated Factor 2 (TRAF2)-deficient B Lymphocytes Reveal Novel Roles for TRAF2 in CD40 Signaling J. Biol. Chem., November 14, 2003; 278(46): 45382 - 45390. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L.-F. Lu, W. J. Cook, L.-L. Lin, and R. J. Noelle CD40 Signaling through a Newly Identified Tumor Necrosis Factor Receptor-associated Factor 2 (TRAF2) Binding Site J. Biol. Chem., November 14, 2003; 278(46): 45414 - 45418. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. A. Haxhinasto and G. A. Bishop A Novel Interaction between Protein Kinase D and TNF Receptor-Associated Factor Molecules Regulates B Cell Receptor-CD40 Synergy J. Immunol., November 1, 2003; 171(9): 4655 - 4662. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R. Smith, R. M. Braziel, S. Paoletti, M. Lipp, M. Uguccioni, and J. T. Rosenbaum Expression of B-cell-attracting chemokine 1 (CXCL13) by malignant lymphocytes and vascular endothelium in primary central nervous system lymphoma Blood, February 1, 2003; 101(3): 815 - 821. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. A. Haxhinasto, B. S. Hostager, and G. A. Bishop Cutting Edge: Molecular Mechanisms of Synergy Between CD40 and the B Cell Antigen Receptor: Role for TNF Receptor-Associated Factor 2 in Receptor Interaction J. Immunol., August 1, 2002; 169(3): 1145 - 1149. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. A. Bishop, B. S. Hostager, and K. D. Brown Mechanisms of TNF receptor-associated factor (TRAF) regulation in B lymphocytes J. Leukoc. Biol., July 1, 2002; 72(1): 19 - 23. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
) or Sf9 cells
infected with a control baculovirus (
). TNF production was measured
by ELISA; similar results were obtained in a second experiment. Results
are presented as the mean ± SE of triplicate samples.
