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Department of Microbiology and Immunology, University of California, San Francisco, CA 94143
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Defining the requirements for follicular exclusion and elimination of autoantigen-binding B cells is a challenging problem that has implications for understanding how tolerance frequently breaks down in states of immunodeficiency (10). Initial studies in anti-HEL Ig/HEL double-transgenic mice indicated that HEL autoantigen-binding B cells could localize in follicles and survive greater than 1 wk in an anergic state (11, 12). When these HEL-specific B cells were placed in mice carrying the same HEL transgene, but containing a normal B cell repertoire, the cells were excluded from follicles and rapidly eliminated (9). Since no differences in serum HEL concentration could be detected in Ig/HEL- and HEL-transgenic mice, the interpretation of these studies was that B cells compete for access to follicular niches and that autoantigen-binding B cells were less competitive than other cells binding Ag more weakly or not at all. Cells that failed to gain access to a follicular niche would then undergo cell death. However, these studies could not rule out the possibility that there were local differences in HEL concentration in the secondary lymphoid tissues of Ig/HEL- and HEL-transgenic mice, and therefore could not exclude an alternate model that the level of BCR engagement alone determines both cell positioning and cell survival (13, 14). In a recent study, we found that B cells deficient in SHP1, a negative regulator of BCR signaling, are spontaneously excluded from follicles in the absence of Ag (15). Follicular exclusion of the cells was conditional on the presence of an excess of wild-type B cells that had normal intracellular signaling. Since there was no requirement for Ag in this system, this study provided strong support for the model that B cells compete for access to follicular niches by a mechanism not involving competition for Ag. However, SHP1-deficient B cells have an intrinsic defect in survival, so the role of competitor cells in their elimination could not be assessed. Furthermore, it is likely that SHP1 regulates cell surface receptors in addition to the BCR (15). For these reasons, it remained important to use further approaches to determine the mechanism by which B cells influence each other’s fate.
Several studies have explored the role of T cells in maintaining tolerance in the B cell compartment. In the anti-H-2k Ig-transgenic model, it has been demonstrated that T cells are not required for deletion of autoreactive B cells (16), and similar studies in the HEL-transgenic model have established that the anergic phenotype induced by soluble HEL is T cell independent (J.G.C. and Christropher C. Goodnow, unpublished observations). In separate studies to test the role of fas in maintaining B cell tolerance, it was found that when anergic HEL-binding B cells were provided with a source of Ag-specific CD4 T cells, the anergic cells were eliminated by T cells in a fas-dependent manner (17). This process might mimic that occurring, for example, when an autoantigen-specific B cell internalizes a complex of autoantigen and foreign Ag and presents some of the foreign determinants to nontolerant T cells. It is not known, however, whether T cells are required for the follicular exclusion and elimination of B cells that occur rapidly following binding of HEL autoantigen in the absence of foreign determinants.
In this study, we have tested the requirement for competitor B cells in
exclusion and elimination of HEL-binding B cells by altering the
presence or absence of B cells as a single variable using wild-type and
B cell-deficient (µMT) mice. We have also tested whether T cells are
required for follicular exclusion or elimination of HEL-binding B cells
using mice deficient in T cells
(TCRß-/-
-/-) or T cells and
B cells (RAG1-/-). We find that competitor B cells, but
not T cells, are needed for follicular exclusion and elimination of
HEL-binding B cells. Unexpectedly, transfers into RAG1-deficient mice
reveal that T cells can help support survival of autoantigen-binding B
cells.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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C57BL/6 (B6) Ig-transgenic mice were of the MD4 line, which
carries transgenes encoding IgMa and
IgDa heavy chains and a light chain that pair to
form a high affinity anti-HEL specificity (5). B6 HEL-transgenic
mice were of the ML5 line, which carries a transgene encoding HEL under
the metallothionein promoter and contains HEL at 10–30 ng/ml in serum
(5, 18). B6 RAG1-/- mice (19), B6 µMT (20), B6
TCRß-/-, and B6
TCRß-/--/- (21, 22) mice were obtained
from The Jackson Laboratory (Bar Harbor, ME), and B6
EBF-/- mice (23) were kindly provided by R. Grosschedl
(University of California at San Francisco).
Chimeric mice
Bone marrow was isolated from at least 6-wk-old B6 or µMT donor mice, as previously described (24). About 2 million cells were injected into the lateral tail vein of B6 or HEL-transgenic recipients that had been lethally irradiated with 1000–1200 rad (Caesium irradiator). The animals received antibiotics (polymixin B, 110 mg/L, and Neomycin, 1.1 g/L) in the drinking water for the whole 6–8-wk reconstitution period until analysis.
Adoptive transfers
Donor cells isolated from the spleen of anti-HEL-transgenic
or nontransgenic B6 mice were labeled with 10 µM 5 (and
6)-carboxyfluorescein-diacetate-succinimidyl-ester (CSFE;
Molecular Probes, Eugene, OR), as described (25). Recipient
nontransgenic, HEL-transgenic, µMT, TCRß-/-,
TCRß-/--/-, and RAG1-/-
mice were injected into the lateral vein with 0.3-ml aliquots of
labeled spleen cells containing about 107 B cells. If the
recipients belonged to HEL-containing groups, they had been injected
with 1 mg HEL in 0.3 ml RPMI i.p. 2 h before cell
transfers. Chimeric mice had been reconstituted for 5–8 wk before cell
transfers. After days 1, 3, or 6, spleen, mesenteric lymph nodes, and
blood were isolated, and cells were prepared as decribed before (5) and
used for flow cytometry. Part of the spleen and one mesenteric lymph
node were frozen in OCT compound (Miles, Elkhart, IN) for sectioning.
HEL ELISA
Blood was collected either from the lateral tail vein (Fig. 1
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or from the thoracic cavity immediately following euthanasia. After
allowing several hours for a clot to form, the blood was microfuged
(14,000 rpm) for 10 min, and the serum was isolated and either stored
at -80°C or used immediately. In most cases, a 30-fold dilution of
the serum was used in the ELISA. A standard curve was generated using
serial threefold dilutions (in the range 0.07–50 ng/ml) of purified
HEL (Sigma, St. Louis, MO) in PBS containing 3% nontransgenic B6 mouse
serum. The sandwich ELISA used to measure the serum HEL was as
previously described (26) using Immulon2 HB 96-well plates (Dynex
Technologies, Chantilly, VA), with HyHEL8 as the capture Ab and
biotinylated HyHEL9 as the detection Ab. Some experiment-to-experiment
variability was encountered with this assay, possibly due to the low
concentrations of HEL in the serum and the propensity of HEL to stick
to serum proteins and surfaces (27). For example, the mean HEL
concentration measured in serum from six ML5 HEL-transgenic mice was 23
ng/ml in one experiment and 28 ng/ml in a second experiment. This
variability makes it difficult to compare HEL concentration
measurements made in different experiments, as has been previously
observed (28). Serum HEL concentrations in µMT and wild-type mice
were therefore measured together in each experiment.
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Cryostat sections (6–7 µm) were fixed and stained as previously described (11). In immunohistochemistry, HEL-binding cells were detected by incubating with HyHEL9-biotin, followed by avidin-conjugated alkaline phophatase (Sigma); mAb specific for B220 (6B2), or CD4 and CD8 (Caltag) were rat IgG Abs and were detected with goat anti-rat-conjugated horseradish peroxidase (Southern Biotechnology Associates, Birmingham, AL). Enzyme reactions were developed with conventional substrates for peroxidases (diaminobenzidine/H2O2) and alkaline phosphatase (FAST RED/Naphtol AS-MX). Sections were counterstained in hematoxylin and mounted in crystal mount (Biomeda, Foster City, CA). For immunofluorescence microscopy, HEL-binding B cells were detected by incubating with HyHEL9-biotin, followed by streptavidin-conjugated Cy-3 (Jackson ImmunoResearch, West Grove, PA), and marginal metallophilic macrophages were identified with MOMA-1 (29), followed by goat anti-rat-conjugated aminomethylcoumarin (Jackson ImmunoResearch). Sections were mounted in fluoromount G (Southern Biotechnology Associates) and viewed with a Leica DMRL fluorescence microscope. Images were acquired on an Optronics MDEI850 cooled CCD video camera (Optronics Engeneering, Goleta, CA) and were processed with Photoshop software (Adope Systems, Mountain View, CA).
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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To study the fate of HEL-binding B cells in mice lacking an
endogenous population of competitor B cells, we used two approaches:
transfer of cells into B cell-deficient µMT mice (20) injected with
soluble HEL, and transfer of cells into lethally irradiated
HEL-transgenic mice reconstituted with µMT bone marrow. For the HEL
injection approach, which was also used in studies of T cell-deficient
and RAG1-deficient mice described below, we initially measured the
serum HEL concentration over time in wild-type mice injected i.p. with
0.1 or 1 mg HEL (Fig. 1
A). In
mice injected with 0.1 mg HEL, the serum concentration dropped rapidly
from µg/ml levels at 1–6 h following injection, to background levels
in 3 days. In animals injected with 1 mg HEL, there was a more
sustained plateau following the initial clearance phase, in which the
concentration remained above 10 ng/ml for more than 3 days (Fig. 1A). Since soluble HEL-transgenic mice (of the ML5 line)
have a serum HEL concentration in the range 10–40 ng/ml (18), the
finding that mice injected with 1 mg HEL contained serum concentrations
above 10 ng/ml for 3 days suggested HEL-injected animals could be used
as substitutes for HEL-transgenic animals. This was tested by
transferring Ig-transgenic B cells into nontransgenic mice injected
with 1 mg HEL or buffer alone 2 h before cell transfer (Fig. 1B). In agreement with previous studies in HEL-transgenic
mice (12), similar numbers of Ig-transgenic B cells were present in the
spleens of HEL-injected or control mice 1 day after transfer, while the
majority of HEL-binding cells had been eliminated in the HEL-injected
mice by day 3 (Fig. 1B). Using this HEL injection approach,
we tested whether competitor B cells were required for the rapid
elimination of HEL-binding cells by transferring Ig-transgenic cells
into wild-type and B cell-deficient (µMT) mice that had been injected
2 h earlier with either buffer or 1 mg HEL. In striking contrast
to the rapid elimination of HEL-binding B cells in wild-type mice, the
majority of HEL-binding cells in B cell-deficient (µMT) mice survived
over the assay period (Fig. 2A). The serum HEL
concentrations at days 3 and 6 in the HEL-injected B cell-deficient and
control mice were equivalent (day 3, µMT, 20 ± 14 and wild
type, 19 ± 8; and day 6, µMT, 19 ± 5 and wild type,
19 ± 9 ng/ml).
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B). Together these experiments
indicate that the enhanced survival of HEL-binding B cells in mice
lacking endogenous B cells results from the absence of other B cells,
and not from differences in HEL Ag concentration or T cell help. Follicular localization of HEL autoantigen-binding B cells in mice lacking other B cells
To investigate whether enhanced survival of HEL
autoantigen-engaged B cells in B cell-deficient mice coincides with
homing to follicles, we analyzed the localization of transferred B
cells in spleen sections by immunohistochemistry. In B cell-deficient
mice lacking HEL Ag, transferred B cells localized in follicular
clusters by day 1 after transfer (Fig. 3B), and their distribution
had changed little by day 3 (not shown). The ability of B cells to home
to follicles in mice that lack B cells suggests that B cell homing
molecules must already be in place, and consistent with this it has
recently been found that lymphocyte-deficient mice make small amounts
of the B cell homing chemokine, BLC, in the spleen (32). In B
cell-deficient mice containing HEL, most of the transferred HEL-binding
cells localized in follicular clusters at day 1, although frequently
the cells were not as tightly packed together as cells in mice lacking
HEL (Fig. 3, D and B). By day 3 after transfer,
the localization of HEL-engaged B cells in B cell-deficient recipient
mice (Fig. 3F) was similar to their distribution in mice
lacking HEL (Fig. 3B). This was in contrast with the outcome
in wild-type mice, in which the HEL-binding cells were distributed in
the outer T zone at day 1 (Fig. 3C) and the few cells that
had not been eliminated by day 3 remained in the T zone (Fig. 3E). To test more definitively whether the areas in which
HEL-binding B cells localize in B cell-deficient mice represent
follicles, we transferred a small number of CFSE-labeled nontransgenic
B cells into HEL-containing wild-type or B cell-deficient mice that had
received Ig-transgenic B cells 2 days earlier. Fourteen hours later,
spleen tissue was isolated and stained to detect the distribution of
HEL-binding cells (red), transferred CFSE+ nontransgenic
cells (green), and marginal zone macrophages (blue; Fig. 3, G and H). Marginal zone macrophages are typically
found at the outer border of lymphoid follicles (33). In wild-type
recipients, the transferred nontransgenic cells had localized in
follicles as expected, while the HEL-binding cells remained excluded to
the outer T zone (Fig. 3G). Strikingly, in B cell-deficient
recipients, the HEL-binding cells and transferred nontransgenic
(CFSE+) B cells were found colocalized in clusters adjacent
to the MOMA-1-positive marginal zone (Fig. 3H). These
findings establish that the HEL-binding cells in B cell-deficient
recipients were located in lymphoid follicles.
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Since autoantigen-binding B cells that are excluded from follicles
localize in the outer T cell zone, it seemed likely that T cells would
play a role in the exclusion or elimination of the B cells. To test
these possibilities, we transferred purified Ig-transgenic B cells into
T cell-deficient mice (TCRß-/--/-),
some of which had been injected with 1 mg HEL. In contrast to their
enhanced survival in B cell-deficient mice, HEL-binding B cells were
eliminated in T cell-deficient mice with an efficiency equal to or
greater than that in wild-type control animals (Fig. 4). Immunohistochemical analysis of
recipient spleens demonstrated that transferred B cells rapidly
localized to follicles in both T cell-deficient mice and wild-type mice
(Fig. 5, A and B).
This is in agreement with previous observations in nude and SCID mice
that resident T cells are not necessary to guide recirculating B cells
to follicles (34, 35, 36). In T cell-deficient recipients containing HEL
Ag, the transferred HEL-binding B cells were excluded from follicles
(Fig. 5D). Minor differences were sometimes observed in the
distribution of excluded cells in T cell-deficient and wild-type mice
(Fig. 5, C and D), and this appeared to reflect
the smaller T zones in the T cell-deficient animals. These observations
demonstrate that T cells are not required for follicular exclusion of
HEL-binding B cells.
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Investigating the survival of autoreactive B cells in mice
that lack both B cells and T cells (RAG1-/-) led to an
unexpected finding. When Ig-transgenic B cells were transferred into
RAG1-/- mice that had been injected with HEL, rather than
surviving as in B cell-deficient recipients, most of the cells were
eliminated in 3 days (Fig. 6A). The control B
cell-deficient recipients in this experiment were lethally irradiated
mice that had been reconstituted with early B cell factor
(EBF)-deficient bone marrow (provided by R. Grosschedl, University of
California at San Francisco). Like µMT mice, EBF-/-
mice lack B cells, but have normal numbers of T cells (23). The failure
of HEL-binding B cells to survive in RAG1-/- recipients
suggested that T cells could enhance the survival of
autoantigen-engaged B cells. In the studies above, we excluded the
possibility that HEL-specific T cells were required for the enhanced
survival of HEL-binding B cells in B cell-deficient mice. However, to
further test whether the T cell-dependent augmentation of HEL-binding B
cell survival could be a result of help from HEL-specific T cells, we
crossed Ig/HEL double-transgenic mice with RAG1-/- mice
and compared the survival of HEL autoantigen-binding B cells developing
in mice lacking T cells (RAG1-/-, Ig/HEL double
transgenic) and in mice containing normal numbers of T cells, but
lacking HEL-specific T cells (RAG1+/-, Ig/HEL double
transgenic). The life span of the HEL autoantigen-engaged B cells was
estimated by measuring the rate of bromodeoxyuridine (BrdU)
incorporation by splenic B cells (12). In agreement with the transfer
studies, more than 90% of the HEL autoantigen-binding B cells in mice
lacking T cells (RAG1-/-) had turned over in 1 wk,
indicating that less than 10% of the cells survived (Fig. 6, B and C), whereas more than 50% of the cells
survived in mice that contained T cells (Fig. 6B).
Importantly, BrdU measurements in RAG1-/- and
RAG1+/- Ig-transgenic mice that lacked HEL demonstrated
that the proportion of naive Ig-transgenic B cells surviving 1 wk was
not detectably affected by the absence or presence of T cells (Fig. 6, B and C). Consistent with the rapid turnover of
autoantigen-binding B cells in the absence of T cells, the number of B
cells in lymph nodes and blood of RAG1-/- Ig/HEL
double-transgenic mice was approximately threefold lower than in
RAG1+/- or RAG+/+ Ig/HEL
double-transgenic controls (data not shown). Taken together these
findings indicate that T cells, directly or indirectly, enhance the
survival of HEL autoantigen-engaged B cells in a
nonautoantigen-restricted manner.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Previous experiments to test whether competitor B cells affect the fate of HEL autoantigen-binding B cells compared HEL-expressing animals containing a normal B cell repertoire with mice containing a monoclonal repertoire of HEL-binding B cells (Ig/HEL double-transgenic mice) (9, 12). A concern that has been raised with these studies is that the HEL concentration in mice with a normal B cell repertoire may be higher than in animals containing large numbers of HEL-binding B cells, in which some HEL might be depleted by the B cells; in this situation, only the mice with the normal repertoire might have HEL above the threshold concentration required for rapid elimination (13). Although it has not been possible to measure significant differences in serum HEL concentration between HEL- or Ig/HEL-transgenic mice, it remains possible that local differences in HEL concentration exist within lymphoid tissues. In this study, we have found that when small numbers of HEL-binding B cells are transferred into HEL-containing wild-type or B cell-deficient mice, cell survival is markedly enhanced in the B cell-deficient group. Since no differences in serum HEL concentration could be detected and the number of Ig-transgenic HEL-binding B cells introduced into the two groups of mice at the start of the experiment was identical, it is unlikely that HEL concentrations in the tissues of B cell-deficient mice were lower than in normal mice. Therefore, the enhanced survival of HEL-binding cells in B cell-deficient recipients cannot be readily explained by lower BCR engagement. Instead, the findings indicate that at the level of BCR engagement typical of soluble HEL-transgenic mice, B cells compete for survival, with HEL autoantigen-binding B cells being less competitive than other mature B cells in the normal repertoire.
The mechanism by which B cells compete for survival is not defined, but previous studies have supported a relationship between competitive exclusion from limiting follicular niches and failure to survive (9, 12). Again, other studies have suggested that B cells do not compete for follicular localization and that cell positioning is determined solely by the extent of Ag receptor engagement (14). However, in the latter studies, the presence or absence of competitor B cells was not controlled as an independent variable, and it remained possible that while BCR engagement above a threshold level was necessary for follicular exclusion, it was not sufficient. Our finding in this study that HEL autoantigen-binding B cells can localize in follicles in mice lacking other B cells, but are excluded when an excess of other B cells is present, provides strong support for the view that B cells compete for access to lymphoid follicles. This conclusion is also supported by the recent finding that spontaneous (HEL Ag-independent) follicular exclusion of SHP1-deficient B cells is conditional on the presence of an excess of wild-type B cells (15). Overall, our results support the model that B cells compete for access to limiting follicular niches to survive. Recently, it has been found that B cells home to splenic follicles in response to a chemokine, BLC, expressed by follicular stromal cells (32, 37). It will be interesting to investigate whether BCR engagement reduces B cell responsiveness to BLC, and whether follicular B cells deplete this chemokine, as these two processes together might provide one mechanism by which B cells compete for follicular localization (38).
Autoantigen-binding B cells that are excluded from migrating into
follicles by competitor B cells localize transiently in the outer T
cell zone before undergoing cell death. When cell survival is prolonged
by overexpression of bcl2, the HEL-binding cells remain in
the outer T zone, suggesting that they normally undergo cell death at
this site (9). It therefore seemed likely that T cells were required
for retaining Ag-engaged B cells in the outer T zone, and possibly for
the elimination of the excluded cells. Both of these possibilities can
now be ruled out because follicular exclusion and elimination of
HEL-binding B cells continue to occur in mice lacking both 
ß and
T cells (Figs. 4 and 5). Although these observations might at
first seem inconsistent with previous studies that have demonstrated
fas-mediated killing of anergic B cells by T cells (17, 39),
the latter studies were performed in irradiated mice that lacked
competitor B cells and involved cognate recognition of the anergic B
cells by autoantigen-specific T cells. The current experiments show
that in the presence of competitor B cells, autoantigen-binding B cells
can be eliminated by a T cell-independent mechanism. Whether other
cells in the T zone, such as stromal cells or dendritic cells, play a
role in follicular exclusion or elimination of autoreactive B cells
will require further work, but this possibility is supported by the
recent finding that both of these cell types make chemokines that can
attract B cells (40, 41).
An unexpected finding in these studies was the failure of HEL-binding B
cells to survive in RAG1-/- mice. Since these mice lack
competitor B cells, it was anticipated that the autoreactive B cells
would survive similarly to cells in B cell-deficient mice. The marked
elimination of the HEL-binding cells in the RAG1-deficient animals
implies that T cells play a protective role in HEL autoantigen-binding
B cell survival. This protective role only becomes easily apparent when
the survival of the autoreactive cells is not compromised by the
presence of competitor B cells. However, consistent with the
possibility that T cells play a similar survival-enhancing role for
autoreactive B cells in mice with a normal B cell compartment, we noted
that the extent of HEL-binding B cell elimination at day 3 after
transfer into T cell-deficient mice was greater than in wild-type
controls (Fig. 4 and data not shown). In a recent study tracking the
fate of anti-dsDNA-reactive B cells, it was found that in addition
to exclusion from follicles and rapid elimination in mice with a
diverse B cell repertoire, dsDNA-reactive B cells were also rapidly
eliminated in RAG2-deficient mice, and it was concluded that
competition between B cells played no role in the elimination of the
autoreactive cells (42). Our data indicate that it may not be possible
to test whether competitor B cells promote elimination of autoreactive
B cells by comparing autoreactive B cell survival in wild-type and
lymphocyte-deficient RAG-/- mice, because the lack of T
cells in the RAG-/- mice could itself compromise B cell
survival. Mice expressing HEL as an autoantigen are generally
considered to lack HEL-specific Th cells (18), and in a study in which
anti-HEL TCR-transgenic mice were crossed with HEL-transgenic mice,
marked deletion of the HEL-specific cells occurred in the thymus (31).
We therefore think it unlikely that the greater survival of HEL-binding
B cells in B cell-deficient mice than in RAG-deficient mice is due to
the presence of HEL-specific Th cells in the former mice, and we favor
the view that T cells are enhancing autoreactive B cell survival in a
manner that is not Ag restricted. A possible example of such a
survival-enhancing activity has been reported in X-linked
immunodeficient (Xid) mice. Due to a mutation in btk, Xid
mice have defective signaling from the BCR and a slight reduction in
numbers of mature B cells (43, 44). However, when the animals are
crossed to T cell-deficient mice, the reduction in B cell numbers is
much more severe (45, 46). Similar findings in Xid mice crossed to
CD40-deficient animals have implicated CD40-CD40L interactions as the
mechanism by which T cells promote Xid B cell survival (47, 48). A
pathway of this type might also operate to enhance autoreactive B cell
survival. Alternatively, the T cell effect might be indirect, perhaps
by increasing the number of B cell-supporting dendritic cells or
stromal cells in the T zones or follicles. Distinguishing between these
possibilities may uncover a novel pathway by which autoreactive B cell
fate is regulated and may help define the basis for the increased
frequency of autoantibody production in patients who have reduced
numbers of B cells, but normal numbers of T cells (49).
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Acknowledgments |
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Footnotes |
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2 Address correspondence and reprint requests to Dr. Jason Cyster, Department of Microbiology and Immunology, Box 0414, University of California, 513 Parnassus Ave., San Francisco, CA 94143. E-mail address:
3 Abbreviations used in this paper: HEL, hen egg lysozyme; BCR, B cell receptor; BLC, B lymphocyte chemoattractant; BrdU, bromodeoxyuridine; CFSE, carboxyfluorescein-diacetate-succinimidyl-ester; EBF, early B cell factor; Xid, X-linked immunodeficient.
Received for publication July 7, 1998. Accepted for publication September 9, 1998.
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References |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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and ß block thymocyte development at different stages. Nature 360:225.[Medline]
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S. C. Morris, M. Moroldo, E. H. Giannini, T. Orekhova, and F. D. Finkelman In Vivo Survival of Autoreactive B Cells: Characterization of Long-Lived B Cells J. Immunol., March 15, 2000; 164(6): 3035 - 3046. [Abstract] [Full Text] [PDF]
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 L. Mandik-Nayak, S.-j. Seo, C. Sokol, K. M. Potts, A. Bui, and J. Erikson MRL-lpr/lpr Mice Exhibit a Defect in Maintaining Developmental Arrest and Follicular Exclusion of Anti-double-stranded DNA B Cells J. Exp. Med., June 7, 1999; 189(11): 1799 - 1814. [Abstract] [Full Text] [PDF]
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H. Noorchashm, A. Bui, H.-L. Li, A. Eaton, L. Mandik-Nayak, C. Sokol, K. M. Potts, E. Pure, and J. Erikson Characterization of anergic anti-DNA B cells: B cell anergy is a T cell-independent and potentially reversible process Int. Immunol., May 1, 1999; 11(5): 765 - 776. [Abstract] [Full Text] [PDF]
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HEL transfer with cells from mice that did not
receive transferred cells.
